Phenomenology 2021 Symposium

24 May 2021, 08:00 → 26 May 2021, 21:30 US/Eastern

University of Pittsburgh

IMPORTANT INFORMATION REGARDING PHENO 2021 IN LIGHT OF THE COVID-19 PANDEMIC

Due to the ongoing COVID-19 pandemic, Pheno 2021 will be host virtually.  The full details of this virtual meeting will be made available soon. Registration for this virtual symposium will be free. The talk schedule will roughly follow the planned schedule as though its a physical meeting and will be held May 24 to May 26.  We would like to encourage you to register and submit an abstract for a parallel talk. We hope to see you online in May!

PROGRAM

The 2021 Phenomenology Symposium will be held May 24-26, 2021 at the University of Pittsburgh.  It will cover the latest topics in particle phenomenology and theory plus related issues in astrophysics and cosmology.

Registration deadline: May 23, 2021

Abstract submission deadline for parallel talks: May 3, 2021 (We do not accept abstracts anymore.)

Confirmed plenary speakers and topics:

• Tulika Bose (UW-Madison, CMS), Recent LHC Results 
• Joseph Bramante (Queen's Univ., McDonald Institute and Perimeter Institute), Dark matter: new searches for ancient particles
• Bhupal Dev (Washington Univ.), Anomalies and their implications
• Keith Ellis (IPPP, Durham Univ.), New perspectives in particle physics
• Henriette Elvang (Univ. of Michigan), Scattering amplitudes and more
• Jim Halverson (Northeastern Univ.), Deep Learning Landscapes
• Laura Jeanty (Univ. of Oregon, ATLAS), Future Perspectives at HL-LHC
• Elizabeth Krause (Univ. of Arizona), Cosmology in 2021: Concordances and Tensions
• Danny Marfatia (Univ. of Hawaii), Non-standard neutrino interactions
• Maura McLaughlin (West Virginia Univ.), Physics with NANOGrav
• Patrick Meade (Stonybrook), Physics opportunities at future colliders
• Knut Moraa (Columbia Univ., XENON1T), Dark matter direct detection
• James Mott (FNAL), Muon g-2 and muon physics on Fermilab campus
• Regina Rameika (FNAL), Perspectives on neutrino physics
• Robyn Sanderson (University of Pennsylvania), GAIA and Dark Matter
• Veronica Sanz (Univ. of Sussex, UK), LHC phenomenology
• Christoph Schwanda (HEPHY, Vienna), Beauty physics from Belle II
• Natalia Toro (SLAC), Probing the dark sector

Mini-Reviews: (1). Hartmut Wittig (Johannes Gutenberg University Mainz), The SM expectation for muon g-2. (2). David Shih (Rutgers University), Anomaly Detection with ML.

Parallel session extension:

Due to the large number of contributed talk submissions, parallel sessions have been extended to include Wednesday afternoon from 2:00pm - 6:30pm. 

FORUM ON EARLY CAREER DEVELOPMENT

Invited Speakers: Julia Gonski (Columbia Univ.), Sara Simon (Fermilab), and Midhat Farooq (APS)
"Physics Career Paths: Finding Success in Academia, Industry, and Beyond"
May 24, 1:00-2:00 PM
The forum will consist of an overview of career paths for physicists followed by time for questions from the participants.

VIRTUAL COCKTAIL HOUR, AWARDS CEREMONY, AND HISTORY OF PHENO

As is a Pheno tradition, we will have a social hour and awards ceremony after the parallel sessions on Tuesday, May 25 at 6:45 PM EDT.  Though we cannot share a drink together, we encourage you to join with your favorite beverage in hand! Award recipients will not be notified in advance, so make sure to join to learn if you won one! 

As a special treat, this year we will welcome Professor Vernon Barger from the University of Wisconsin - Madison to share with us the history and his reminiscences of the Phenomenology Symposia.

PHENO 2021 ORGANIZERS: Ayres Freitas, Joni George, Tao Han (chair), Adam Leibovich, Cédric Weiland, Benjamin Carlson, Brian Batell, Akshay Ghalsasi and Keping Xie.

PHENO 2021 PROGRAM ADVISORS: Vernon Barger, Lisa Everett, Kaoru Hagiwara, JoAnne Hewett, Tae Min Hong, Arthur Kosowsky, James Mueller, Vittorio Paolone, Tilman Plehn, Vladimir Savinov, Xerxes Tata, Andrew Zentner, and Dieter Zeppenfeld.

More information to come.

PHENO 2020

Pheno21final.pdf

pheno21schedulesafe.pdf

Monday 24 May

08:40 → 10:30 Plenary: I

https://pitt.zoom.us/j/93951025550

Conveners: Keith Dienes (University of Arizona), Keith Dienes (University of Arizona), Keith Dienes (University of Arizona)

zoom

08:40 Welcome

Speaker: Prof. Kathy Blee (University of Pittsburgh)

08:45 Dark matter direct detection

Speakers: Knut Moraa (Columbia University), Knut Morå (Columbia University)

Pheno2021_Moraa.pdf

09:20 Dark matter: new searches for ancient particles

Speaker: Joseph Bramante (Queen's University & Perimeter Institute)

DMNSBramantePHENO2021.pdf

09:55 Probing the dark sector

Speakers: Natalia Toro (SLAC), Prof. Natalia Toro (SLAC National Accelerator Laboratory), natalia toro (Stanford University)

PHENO 2021 Dark Sectors.pdf

10:30 → 11:00 Coffee Break

11:00 → 12:45 Plenary: II

https://pitt.zoom.us/j/93951025550

Convener: Lisa Everett

zoom

11:00 Dynamical tests of dark matter in the Milky Way

Speaker: Robyn Sanderson (University of Pennsylvania)

Sanderson_Pheno21.pdf

11:35 Physics with NANOGrav

Speakers: Prof. Maura McLaughlin (West Virginia University), Maura McLaughlin

Pheno2021.pptx

12:10 Cosmology in 2021: Concordances and Tensions

Speakers: Elisabeth Krause (The University of Arizona), Elizabeth Krause

Krause_Pheno21.pdf

12:45 → 13:00 .

12:45 → 14:15 Lunch

13:00 → 14:00 Career Forum

Gonski_Pheno_2021.pdf

Simon_Pheno_2021.pdf

14:00 → 14:15 .

14:15 → 16:00 Axions & ALPs I

Zoom link Axions & ALPs I

14:15 An even lighter QCD axion

We explore whether the axion which solves the strong CP problem can naturally be much lighter than the canonical QCD axion. The Z_N symmetry proposed by Hook, with N mirror and degenerate worlds coexisting in Nature and linked by the axion field, is considered and the associated phenomenology is studied in detail.
On a second step, we show that dark matter can be accounted for by this extremely light axion. This includes the first proposal of a ``fuzzy dark matter'' QCD axion. A novel misalignment mechanism occurs -- trapped misalignment-- due to the peculiar temperature dependence of the Z_N axion potential, which in some cases can also dynamically source the recently proposed kinetic misalignment mechanism.
The resulting universal enhancement of all axion interactions relative to those of the canonical QCD axion has a strong impact on the prospects of ALP experiments such as ALPS II, IAXO and many others. For instance, even Phase I of Casper Electric could discover this axion.
Based on 2102.00012 and 2102.01082.

Speaker: Dr Pablo Quilez Lasanta (DESY)

An even lighter QCD axion- Pheno 21.pdf

14:30 The $\nu$DFSZ Axion model dubbed 2hdSMASH

The Standard Model (SM) suffers from five shortcomings: Dark Matter, Neutrino masses and mixing, Baryon asymmetry, Strong CP-Problem and Inflation. The latter is regarded as the seeds for structure formation. In this talk, we introduce an inflationary $\nu$DFSZ-type axion model which is dubbed 2hdSMASH (Two-Higgs-Doublet SM * Axion * Seesaw * Higgs-Portal-Inflation). 2hdSMASH aims at giving a complete and unified picture of the universe evolution from the inflationary epoch to today. In particular, we focus on parameter constraints coming from the inflationary epoch which provide in the low energy limit phenomenologically viable scalar masses that can be tested at LHC, HL-LHC or future colliders

Speaker: Mr Michael Maxim Matlis (Deutsches Elektronen-Synchrotron DESY)

Matlis-Presentation.pdf

14:45 High quality axions in solutions to the $\mu$ problem

We consider supersymmetric extensions of DFSZ type axion models with the field content of the MSSM plus some extra vectorlike quark and lepton supermultiplets that simultaneously give a solution to the $\mu$ problem and the strong CP problem. The extra vectorlike content is chosen such that the perturbative gauge coupling unification is maintained. We identify Peccei-Quinn (PQ) symmetry that is protected to a high degree of accuracy as an accidental symmetry emerging from anomaly-free discrete symmetries with or without a discrete version of the Green-Schwarz mechanism. The PQ symmetry is spontaneously broken with two gauge singlets acquiring intermediate scale vacuum expectation values giving rise to a high-quality invisible axion and a $\mu$ term around the TeV scale. After the PQ breaking the axion potential typically acquires more than one inequivalent degenerate minima leading to a cosmological domain wall problem. We therefore pay special attention to the models that evade this problem.

Speaker: Mr Prudhvi Bhattiprolu (Northern Illinois University)

pbhattiprolu_pheno21.pdf

15:00 $SU(5) \times U(1)_X$ Axion Model with Observable Proton Decay

We propose a $SU(5) \times U(1)_X \times U(1)_{PQ}$ model, where $U(1)_X$ is the generalization of the $B-L$ (baryon minus lepton number) gauge symmetry and $U(1)_{PQ}$ is the global Peccei-Quinn (PQ) symmetry. There are four fermions families in $\bf{{\overline 5}} + \bf{10}$ representations of $SU(5)$, a mirror family in $\bf{5}+\bf{{\overline {10}}}$ representations, and three $SU(5)$ singlet Majorana fermions. The $U(1)_X$ related anomalies all cancel in the presence of the Majorana neutrinos. The $SU(5)$ symmetry is broken at $M_{GUT} \simeq (4-7)\times 10^{15}$ GeV and the proton lifetime $\tau_p$ is estimated to be well within the expected sensitivity of the future Hyper-Kamiokande experiment, $\tau_p \lesssim 1.3 \times 10^{35}$ years. The $SU(5)$ breaking also triggers the breaking of the PQ symmetry, resulting in axion dark matter (DM), with the axion decay constant $f_a$ of order $M_{GUT}$ or somewhat larger. The CASPEr experiment can search for such axion DM candidates. With the identification of the $U(1)_X$ breaking Higgs field with the inflaton field, we implement low scale inflection-point inflation with $H_{inf} < 10^9 $ GeV which successfully resolve the cosmologically fatal axion domain wall, axion DM isocurvature and $SU(5)$ monopole problems. The vectorlike fermions in the model are essential for achieving a successful unification of the SM gauge couplings as well as the phenomenological viability of both axion DM and inflation scenario.

Speaker: Digesh Raut (University of Delaware)

DR_Pheno_2021.pdf

15:15 Photophilic hadronic axion from heavy magnetic monopoles

We propose a model for the QCD axion which is realized through a coupling of the Peccei-Quinn scalar field to magnetically charged fermions at high energies. We show that the axion of this model solves the strong CP problem and then integrate out heavy magnetic monopoles using the Schwinger proper time method. We find that the model discussed yields axion couplings to the Standard Model which are drastically different from the ones calculated within the KSVZ/DFSZ-type models, so that large part of the corresponding parameter space can be probed by various projected experiments. Moreover, the axion we introduce is consistent with the astrophysical hints suggested both by anomalous TeV-transparency of the Universe and by excessive cooling of horizontal branch stars in globular clusters. We argue that the leading term for the cosmic axion abundance is not changed compared to the conventional pre-inflationary QCD axion case for axion decay constant $f_a > 10^{12}~\text{GeV}$.

Speaker: Anton Sokolov

Sokolov_PHENO21.pdf

15:30 Hunting for axions in the solar basin

A large flux of axion-like particles can be produced in the solar core. While the majority of these particles will have high velocities and escape the Sun’s gravitational pull, a small fraction of low-velocity particles will become trapped on bound orbits. Over time, an appreciable density of slow-moving axions can accumulate in this “solar basin.” Their subsequent decay to two photons provides a distinct observational signature. I will present an ongoing analysis using the NuSTAR X-ray telescope to search for the decay products of keV-scale axions trapped in the solar basin.

Speaker: William DeRocco (Stanford University)

pheno_2021_derocco.pdf

15:45 B-modes from Post-inflationary Gravitational Waves Sourced by Axionic Instabilities at Cosmic Reionization

We show that axion-like particles that the only couple to invisible dark photons can generate visible B-mode signals around the reionization epoch. The axion field starts rolling shortly before reionization, resulting in a tachyonic instability for the dark photons. This generates an exponential growth of the dark photon quanta sourcing both scalar metric modes and gravitational waves that leave an imprint on the reionized baryons. The tensor modes modify the cosmic microwave background (CMB) polarization at reionization, generating visible B-mode signatures for the next generation of CMB experiments for parameter ranges that satisfy the current experimental constraints.

Speaker: Sida Lu (University of Wisconsin-Madison)

Bmode_SL_Pheno21.pdf

14:15 → 16:00 BSM I

Convener: Christopher Robyn Hayes (University of Michigan (US))

zoom

14:15 Search for long-lived particles in CMS

This talk discusses new techniques to detect signatures potentially originating from long-lived particles in the CMS detector, presents recent results from such searches in CMS using the full Run-II data-set of the LHC, and discusses prospects for Run-III

Speaker: Celia Fernandez Madrazo (Instituto de Física de Cantabria)

CFM-Pheno21.pdf

14:30 Searches for New Long-lived Particles with the ATLAS detector

Abstract: Various models of physics Beyond the Standard Model lead to signatures with long-lived particles, such that the decay of the new particle is at a significant distance from the collision point. These striking signatures provide interesting technical challenges due to their special reconstruction requirements as well as their unusual backgrounds. This talk will present recent results in searches for new, long-lived particles using ATLAS Run 2 data.

Speaker: Jackson Carl Burzynski (University of Massachusetts (US))

PHENO21.pdf

14:45 Triggering long-lived particles in HL-LHC and the challenges in the first stage of the trigger system

Triggering long-lived particles (LLPs) at the first stage of the trigger system is very crucial in LLP searches to ensure that we do not miss them at the very beginning. The future High Luminosity runs of the Large Hadron Collider will have an increased number of pile-up events per bunch crossing. There will be major upgrades in hardware, firmware and software sides, like tracking at level-1 (L1). The L1 trigger menu will also be modified to cope with pile-up and maintain the sensitivity to physics processes. In our study we found that the usual level-1 triggers, mostly meant for triggering prompt particles, will not be very efficient for LLP searches in the 140 pile-up environment of HL-LHC, thus pointing to the need to include dedicated L1 triggers in the menu for LLPs. We consider the decay of the LLP into jets and develop dedicated jet triggers using the track information at L1 to select LLP events. We show in our work that these triggers give promising results in identifying LLP events with moderate trigger rates.

Speaker: Prabhat Solanki (Indian Institute of Science, Bengaluru, India)

PSOLANKI_PHENO2021.pdf

15:00 Using unsupervised machine learning to find SUEP at the LHC

Models with dark showers represent one of the most challenging possibilities for new physics at the LHC. One of the most difficult examples is a novel collider signature called a Soft Unclustered Energy Pattern (SUEP), which can arise in certain BSM models with a hidden valley sector that is both pseudo-conformal and strongly coupled. Large-angle emissions are unsuppressed during the showering process, and if the hidden sector hadrons decay hadronically and promptly back into the Standard Model, the result is a high-multiplicity shower of SM final state particles that possess more democratically distributed energies and a much higher degree of isotropy than typically seen in QCD jets. This signature presents significant challenges to trigger on and search for, due to the lack of isolated hard objects to identify in the detector. We outline an analysis strategy to look for SUEP produced by exotic decays of the Higgs boson, using both conventional cuts on event-level observables and anomaly detection methods from machine learning. We find that for some regions of dark shower parameter space, data from the HL-LHC could be used to exclude branching ratios of Higgs decay to SUEP down to a few percent.

Speaker: Jared Barron (University of Toronto)

SUEP_ML_PHENO2021.pdf

15:15 Promptly decaying SUEP signals at the LHC

Models with dark showers represent one of the most challenging possibilities
for new physics at the LHC. The most difficult to detect variety of
these models is so-called Soft Unclustered Energy Pattern (SUEP).  This signature presents significant challenges to trigger on and search for, in part due to the lack of isolated hard objects to identify in the detector as well as the large amount of QCD background in the relevant SUEP phase space.
Signatures like this appear in models with a hidden valley sector that is both
pseudo-conformal and strongly coupled. In such models large-angle emissions are unsuppressed during the showering process. If the hidden sector hadrons decay promptly back into Standard Model hadrons, the result is a high-multiplicity shower of SM final state particles with a more democratic distribution of energies and a much higher degree of isotropy than typically seen in QCD jets.
We outline an analysis strategy to look for SUEP produced by exotic decays of the Higgs boson, using both conventional cuts on event-level observables as well as supervised and unsupervised machine learning anomaly detection methods. We identify the regions of dark shower parameter space which yield SUEP-like Higgs decays and discuss different exclusion methods for various benchmarks. We discuss how search strategies differ depending on the details of the signal generated in different regions of parameter space.

Speaker: Aris-George-Baldur Spourdalakis

Pheno_Presentation.pdf

15:30 Jet Timing for LLP Searches

The search for long-lived particles (LLP) at the LHC can be improved with timing information. If the visible decay products of the LLP form jets, the arrival time is not well-defined. In this talk, I will discuss possible definitions and how they are affected by the kinematics of the underlying parton-level event.

Speaker: Wen Han Chiu (University of Chicago)

Pheno Talk Wen Han Chiu.pdf

15:45 GAZELLE - a long-lived particle detector for Belle II?

Many BSM models predict long-lived particles (LLPs) which are generally difficult to detect at existing colliders. We have explored the potential of a future far detector at Belle II, named GAZELLE. For that, we have investigated three models that predict LLPs with different production mechanisms. In this talk, I will compare the projections of finding these LLPs at Belle II or GAZELLE. Due to Belle II's excellent sensitivity to LLPs, we find little extra gain in building a far detector like GAZELLE.

Speaker: Ruth Schäfer (Universität Heidelberg)

Physics reach of a long-lived particle detector at Belle II

Schaefer_GAZELLE_PHENO21.pdf

14:15 → 16:00 Cosmology I

https://pitt.zoom.us/j/91032362960

Zoom

14:15 Classical Cosmological Collider Physics

Massive field excitations during the inflationary era, imprinted on cosmological correlation functions, have been studied as a unique opportunity to probe heavy degrees of freedom beyond the terrestrial colliders. In the simplest inflationary models, any such cosmological collider signal is exponentially suppressed for fields much heavier than the inflationary Hubble scale, limiting the potential reach of such new physics searches. We show that existence of high-frequency classical oscillations can resonantly enhance heavy field signals. In particular, we study two concrete examples of such classical oscillations: (i) coherent oscillation of another massive field, classically excited due to a sharp feature in a generic multi-field scenario, and (ii) sub-dominant oscillations of the inflaton itself, as a result of periodic features on the inflationary potential.

Speaker: Reza Ebadi (University of Maryland College Park)

14:30 Massless Preheating and Electroweak Vacuum Metastability

Current measurements of Standard-Model parameters suggest that the electroweak vacuum is metastable. This metastability has important cosmological implications because large fluctuations in the Higgs field could trigger vacuum decay in the early universe. For the false vacuum to survive, interactions which stabilize the Higgs during inflation—e.g., inflaton-Higgs interactions or non-minimal couplings to gravity—are typically necessary. However, the post-inflationary preheating dynamics of these same interactions could also trigger vacuum decay, thereby recreating the problem we sought to avoid. This dynamics is often assumed catastrophic for models exhibiting scale invariance since these generically allow for uninterrupted growth of fluctuations. In this talk, we examine the dynamics of such "massless preheating" scenarios and show that the competing threats to metastability can nonetheless be balanced to ensure viability. We find that fully accounting for both the backreaction from particle production and the effects of perturbative decays reveals a large number of disjoint "islands of (meta)stability" over the parameter space of couplings. Ultimately, the interplay among Higgs-stabilizing interactions plays a significant role, leading to a sequence of dynamical phases that effectively extend the metastable regions to large Higgs-curvature couplings.

Speaker: Jeff Kost (University of Sussex)

KOST_talk.pdf

14:45 Electroweak Phase Transition with an SU(2) Dark Sector

We consider a non-Abelian dark SU(2)D model where the dark sector couples to the Standard Model (SM) through a Higgs portal. We investigate two different scenarios of the dark sector scalars with Z2 symmetry, with Higgs portal interactions that can introduce mixing between the SM Higgs boson and the SM singlet scalars in the dark sector. We utilize the existing collider results of the Higgs signal rate, direct heavy Higgs searches, and electroweak precision observables to constrain the model parameters. The SU(2)D partially breaks into U(1)D gauge group by the scalar sector. The resulting two stable massive dark gauge bosons and pseudo-Goldstone bosons can be viable cold dark matter candidates, while the massless gauge boson from the unbroken U(1)D subgroup is a dark radiation and can introduce long-range attractive dark matter (DM) self-interaction, which can alleviate the small-scale structure issues. We study in detail the pattern of strong first-order phase transition and gravitational wave (GW) production triggered by the dark sector symmetry breaking, and further evaluate the signal-to-noise ratio for several proposed space interferometer missions. We conclude that the rich physics in the dark sector may be observable with the current and future measurements at colliders, DM experiments, and GW interferometers.

Speaker: Hongkai Liu (PITT)

Hongkai_Pheno.pdf

15:00 Influence of asymmetry of potential on stability of domain walls

We study the evolution of cosmological domain walls in models with asymmetric potentials. Our research goes beyond the standard case of spontaneous breaking of an approximate symmetry. The time after which the network will decay depends on the difference of values of the potential in minima, its asymmetry around the maximum separating minima and the bias of initial distribution. Using numerical lattice simulations we determine relative importance of these factors on decay time of networks for generic potentials. We find that even very small departures from the symmetric case lead to rapid decay of the domain wall network. As a result creation of a long lasting network capable of producing observable gravitational wave signals is much more difficult than previously thought.

Speaker: Tomasz Krajewski (University of Warsaw)

TKrajewski.pdf

15:15 Hidden Naturalness in the Light of Cosmological Data

Hidden naturalness offers an exciting framework for alleviating the Higgs hierarchy problem. But because the models within this framework face few constraints from collider searches, there is strong motivation to study their cosmological signatures, an area that has remained mostly unexplored. One of the simplest models that can be studied in this framework is the mirror twin Higgs (MTH) model, a model that contains a near-mirror copy of the SM. Cosmologically, the MTH model is quite complex, containing new sources of free-streaming radiation, interacting radiation, and interacting dark matter. In this talk I will discuss how cosmological datasets, including the CMB temperature and polarization power spectra as measured by the Planck collaboration, constrain the parameter space of the MTH model. In addition, I will also show how this model may help in ameliorating the tensions in the cosmological datasets, specifically those related to the sigma8 and H0 measurements.

Speaker: Saurabh Bansal (University of Notre Dame)

Bansal-Pheno21-v2.pdf

15:30 Inflation From The MSSM

Taking the minimalistic approach, within MSSM, we propose the model of inflation in which the inflaton field is a scalar component of the MSSM state(s).
Two cases will be discussed, which (both) turn out to be very predictive. The inflationary phase is fully governed by the MSSM Yukawa superpotential couplings. The values of the scalar spectral index and the tensor-to-scalar ratio are predicted to be ns≃0.966 and r=0.00118. The postinflation reheating of the Universe proceeds by the decay of the inflaton with the reheating temperature around 10 thousands TeV.
Some phenomenological implication will be also discussed.

Speaker: Prof. Zurab Tavartkiladze (Ilia State University)

2021.05.24-Tavartkiladze-Pheno2021.pdf

15:45 Messenger inflation in gauge mediation and superWIMP dark matter

We discuss phenomenological viability of a novel inflationary model in the minimal gauge mediated supersymmetry breaking scenario.
In this model, cosmic inflation is realized in the flat direction along the messenger supermultiplets and a natural dark matter candidate is the gravitino from the out-of-equilibrium decay of the bino-like neutralino at late times, which is called the superWIMP scenario.
The produced gravitino is warmish and can have a large free-streaming length; thus the cusp anomaly in the small scale structure formation may be mitigated.
We show that the requirement of the Standard Model Higgs boson mass to be $m_{h^0}=125.1$ GeV gives a relation between the spectrum of the cosmic microwave background and the messenger mass $M$.
We find, for the e-folding number $N_e=60$, the Planck 2018 constraints (TT, TE, EE+lowE+lensing+BK15+BAO, 68\% confidence level) give
$M > 3.64\times 10^7$ GeV.
The gravitino dark matter mass is $m_{3/2} < 5.8$ GeV and the supersymmetry breaking scale $\Lambda$ is found to be in the range
$(1.28-1.33)\times 10^6$ GeV.
Future CMB observation is expected to give tighter constraints on these parameters.

Speaker: Shinsuke Kawai (Sungkyunkwan University)

Pheno2021.pdf

14:15 → 16:00 DM I

Convener: Ahmed Ismail

Zoom link DM I

14:15 Dark Matter searches in CMS

Searches in CMS for dark matter particles, mediators, and dark sector extensions will be presented. Various final states, topologies, and kinematic variables are explored utilizing the full Run-II data-set collected at the LHC.

Speaker: Praveen Chandra Tiwari (Indian Institute of Science (IN))

14:30 Searches for dark matter with the ATLAS detector

The presence of a non-baryonic Dark Matter (DM) component in the Universe is inferred from the observation of its gravitational interaction. If Dark Matter interacts weakly with the Standard Model (SM) it could be produced at the LHC. The ATLAS experiment has developed a broad search program for DM candidates, including resonance searches for the mediator which would couple DM to the SM, searches with large missing transverse momentum produced in association with other particles (light and heavy quarks, photons, Z and H bosons) called mono-X searches and searches where the Higgs boson provides a portal to Dark Matter, leading to invisible Higgs decays. The results of recent searches on 13 TeV pp data, their interplay and interpretation will be presented. Prospects for HL-LHC will also be discussed.

Speaker: Luigi Sabetta (Sapienza Universita e INFN, Roma I (IT))

Pheno21_Sabetta.pdf

14:45 Mediator-Induced Decay Chains and Multijet Collider Signatures from Non-Minimal Dark Sectors

If the dark sector contains multiple components with similar quantum numbers which communicate with the visible sector only through a mediator, then this mediator also generically gives rise to dark-sector decays, with heavier dark components decaying to lighter ones. Successive such decays lead to extended decay chains in which visible matter is also produced at every decay step. In this talk, I explore the collider consequences of such decay chains in the case in which the mediator couples to the quark sector of the Standard Model. I discuss the properties of the multi-jet signatures that arise in such scenarios and show that within relatively large regions of parameter space, these signatures are not excluded by existing monojet and multi-jet searches. Such decay cascades therefore represent a potential discovery route for multi-component dark sectors at current and future colliders.

Speaker: Brooks Thomas (Lafayette College)

Brooks-Thomas-PHENO-2021.pdf

15:00 Tumblers: A Novel Signal for Dark Matter and Its Discovery Prospects at Colliders

In this paper, we point out a novel signature of physics beyond the Standard Model which could potentially be observed both at the High-Luminosity LHC (HL-LHC) and at future colliders. We call such a signature a "tumbler." In this talk, I discuss the prospects for observing tumbler signatures at the HL-LHC, taking into account the enhanced timing capabilities afforded by the upgraded LHC detectors. We not only find that a statistically significant number of tumbler events could potentially be observed at the HL-LHC, but also find that meaningful measurements of the masses and couplings of the dark particles involved can be obtained from a reasonably small sample of such events.

Speaker: Tara Leininger (Lafayette College)

PHENO presentation.pdf

15:15 Experimental signatures of a new dark matter WIMP

The dark matter WIMP proposed here has the following properties: (1) According to a rigorous theorem, its mass is $\le 125$ GeV. (2) According to approximate calculations of its annihilation cross-section, it will yield the observed dark matter abundance if its mass is $\sim$ 75 GeV. We also estimate that (3) the cross-section for nuclear scattering is consistent with the limits from direct detection experiments, (4) the cross-section for collider production is consistent with limits from the LHC, and (5) the cross-section for annihilation is consistent with the general (multiple-channel) limits from gamma-ray observations of dwarf spheroidal galaxies. The mass and annihilation cross-section (through 29 different channels) are in agreement with (6) analyses of the observations of gamma rays from the Galactic center by Fermi-LAT (supporting the hypothesis of WIMP annihilation) and (7) analyses of the antiprotons observed by AMS-02 (supporting this same hypothesis). (8) The most promising signature for collider detection appears to be missing transverse energy of $\sim$ 150 GeV following creation through vector boson fusion. (9) The best hope for direct detection is still Higgs exchange, although the coupling to the Higgs boson is undetermined. (10) According to another rigorous theorem, the present dark matter particle and the lightest neutralino of supersymmetry (susy) can stably coexist in a multicomponent dark matter scenario. This new dark matter candidate results from an extended Higgs sector which, if susy is included, implies a doubly rich plethora of new particles and new physics that should be observable in the foreseeable future.

Speaker: Roland Allen (Texas A&M University)

Roland-Allen-PHENO-2021.pdf

15:30 Exploring Multilepton Signatures From Dark Matter at the LHC

Limitations on the most general mono-X Dark Matter signature at colliders motivate searches beyond this, such as multilepton plus missing energy signatures. In this talk I present our latest limits on the inert 2-Higgs Doublet model (I2HDM) and Minimal Fermion Dark Matter model (MFDM) for 8/13 TeV pp collisions at the LHC, producing 2-3 leptons plus missing energy final states, using CheckMATE. I will show how 3 lepton final states play an important role, with a leading role in the MFDM case via cascading Higgs decays. We also provide limits and efficiencies for re-interpretation of any scalar of fermion DM model by the community.

Speaker: Arran Charles Freegard (Queen Mary University of London (GB))

Exploring Multilepton Signatures From Dark Matter at the LHC Phenomenology 2021 Symposium 24_05_21.pdf

15:45 Right Handed Neutrinos, TeV Scale BSM Neutral Higgs and FIMP Dark Matter in EFT Framework

We consider an effective field theory framework with three standard model (SM) gauge singlet right handed neutrinos, and an additional SM gauge singlet scalar field. The framework successfully generates eV masses of the light neutrinos via seesaw mechanism, and accommodates a feebly interacting massive particle (FIMP) as dark matter candidate. Two of the gauge singlet neutrinos participate in neutrino mass generation, while the third gauge singlet neutrino is a FIMP dark matter. We explore the correlation between the ${\it vev}$ of the gauge singlet scalar field which translates as mass of the BSM Higgs, and the mass of dark matter, which arises due to relic density constraint. We furthermore explore the constraints from the light neutrino masses in this set-up. We chose the gauge singlet BSM Higgs in this framework in the TeV scale. We perform a detailed collider analysis to analyse the discovery prospect of the TeV scale BSM Higgs through its di-fatjet signature, at a future $pp$ collider which can operate with $\sqrt{s}=100$ TeV c.m.energy.

Speaker: ROJALIN PADHAN (Institute of Physics, Bhubaneswar)

pheno2021_Rojalin.pdf

14:15 → 16:00 DM VII

Convener: Pouya Asadi (Massachusetts Institute of Technology)

Zoom link DM VII

14:15 Dark-sector physics at Belle II

The Belle II experiment at the asymmetric $e^+e^-$ collider, SuperKEKB, is a substantial upgrade of the Belle/KEKB experiment. Belle II aims to record 50 ab$^{-1}$ of data over the course of the project. During the first physics runs in 2018-2020, around 100 fb$^{-1}$ of data were collected. These early data include specifically-designed low-multiplicity triggers which allow a variety of searches for light dark matter and dark-sector mediators in the GeV mass range. This talk will present the very first world-leading physics results from Belle II: searches for the invisible decays of a new vector Z’, and visible decays of an axion-like particle; as well as the near-term prospects for other dark-sector searches. Many of these searches are competitive with the data already collected or the data expected in the next few years of operation.

Speaker: Katharina Dort (CERN, Justus-Liebig-Universitaet Giessen (DE))

20210524_PHENO2021_DSSearches_kdort.pdf

14:30 Phenomenology of Inelastic Dark Matter at the SBN Experiments

We study the prospects for probing models of inelastic dark matter (iDM) at the Fermilab-based Short Baseline Neutrino (SBN) experiments. In iDM models, elastic scattering of dark matter is suppressed, but the dark matter has an inelastic interaction with a slightly heavier excited dark sector state. The high-intensity Booster and NuMI proton beams can produce dark sector states in the MeV to GeV mass range that can then be detected at the SBN experiments. If the splitting between the two dark matter states is small, then excited dark sector states can propagate into the detectors and decay there. We demonstrate that the SBN experiments can probe new parts of iDM parameter space. Our study notably includes a simulation of iDM production and decay in the detectors, with a comparison to simulated backgrounds from neutrino scattering.

Speaker: Joshua Berger (Colorado State University)

jberger.pdf

14:45 Searching for light dark matter at Fermilab's proton-fixed target experiment: DarkQuest

Accelerator-based searches for dark matter provide a unique opportunity to expand the search for particle dark matter to the sub-GeV mass regime.
In this region, there are exiting opportunities to search for dark sector signatures, mediators and the dark matter itself, that are unconstrained.
DarkQuest is a proton fixed-target experiment that would use a high-intensity beam of 120 GeV protons to produce dark sector mediators.
These mediators will interact feebly with the SM and decay into visible states with displaced lepton, photon and hadron decay signals.
DarkQuest will exploit the short baseline and compact spectrometer of the current beam dump experiment at Fermilab, SpinQuest, to search for these decays.
Because it builds on existing accelerator and detector infrastructure, it offers a powerful yet low-cost experimental initiative that can be realized on a short timescale.
In this talk we will discuss the current detector design, proposed upgrades and recent studies on the signal topology and the detector acceptance.

Speakers: Cristina Ana Mantilla Suarez (Fermi National Accelerator Lab. (US)), Yongbin Feng (Fermi National Accelerator Lab. (US))

CMS_DQ_May24_pheno.pdf

15:00 The Light Dark Matter eXperiment, LDMX

The constituents of dark matter are still unknown, and the viable possibilities span a very large mass range. Specific scenarios for the origin of dark matter sharpen the focus on a narrower range of masses: the natural scenario where dark matter originates from thermal contact with familiar matter in the early Universe requires the DM mass to lie within about an MeV to 100 TeV. Considerable experimental attention has been given to exploring Weakly Interacting Massive Particles in the upper end of this range (few GeV – ~TeV), while the region ~MeV to ~GeV is largely unexplored. Most of the stable constituents of known matter have masses in this lower range, tantalizing hints for physics beyond the Standard Model have been found here, and a thermal origin for dark matter works in a simple and predictive manner in this mass range as well. It is therefore a priority to explore. If there is an interaction between light DM and ordinary matter, as there must be in the case of a thermal origin, then there necessarily is a production mechanism in accelerator-based experiments. The most sensitive way, (if the interaction is not electron-phobic) to search for this production is to use a primary electron beam to produce DM in fixed-target collisions. The Light Dark Matter eXperiment (LDMX) is a planned electron-beam fixed-target missing-momentum experiment that has unique sensitivity to light DM in the sub-GeV range. This contribution will give an overview of the theoretical motivation, the main experimental challenges and how they are addressed, as well as projected sensitivities in comparison to other experiments.

Speaker: Christian Herwig (Fermi National Accelerator Lab. (US))

herwig_ldmx.pdf

15:15 Detecting Dark Matter with Far-Forward Emulsion and Liquid Argon Detectors at the LHC

New light particles may be produced in large numbers in the far-forward region at the LHC and then decay to dark matter, which can be detected through its scattering in far-forward experiments. In the talk, we will discuss the discovery potential of such far-forward searches for light dark matter scattering off electrons or nuclei in an emulsion or liquid argon detector placed on the beam collision axis during HL-LHC. For illustration, we will focus on a popular example of invisibly-decaying dark photons, which decay to dark matter through $A' \to \chi \chi$, while further prospects for probing BSM interactions of neutrinos will also be presented. These results motivate the construction of far-forward emulsion and liquid argon (FLArE) detectors, as well as a suitable location to accommodate them, such as the proposed Forward Physics Facility.

Speaker: Sebastian Trojanowski

Pheno2021_STrojanowski.pdf

15:30 Exoplanets as Sub-GeV Dark Matter Detectors

We present exoplanets as new targets to discover Dark Matter (DM). Throughout the Milky Way, DM can scatter, become captured, deposit annihilation energy, and increase the heat flow within exoplanets. We estimate upcoming infrared telescope sensitivity to this scenario, finding actionable discovery or exclusion searches. Supporting evidence of a DM origin can be identified through DM-induced exoplanet heating correlated with Galactic position, and hence DM density. This provides new motivation to measure the temperature of the billions of brown dwarfs, rogue planets, and gas giants peppered throughout our Galaxy.

Speaker: Juri Smirnov (Ohio State University, CCAPP)

Pheno_Exoplanets as Sub-GeV DM Detectors.pdf

15:45 Machine Learning the 6th Dimension: Stellar Radial Velocities from 5D Phase-Space Correlations

The Gaia satellite will observe the positions and velocities of over a billion Milky Way stars. In the early data releases, the majority of observed stars do not have complete 6D phase-space information. We demonstrate the ability to infer the missing line-of-sight velocities until more spectroscopic observations become available. We utilize a novel neural network architecture that, after being trained on a subset of data with complete phase-space information, takes in a star’s 5D astrometry (angular coordinates, proper motions, and parallax) and outputs a predicted line-of-sight velocity with an associated uncertainty. Working with a mock Gaia catalog, we show that the network can successfully recover the distributions and correlations of each velocity component for stars that fall within ∼ 5 kpc of the Sun. We also demonstrate that the network can accurately reconstruct the velocity distribution of a kinematic substructure in the stellar halo that is spatially uniform, even when it comprises a small fraction of the total star count. Follow-up work includes applying the network to the Gaia catalogue and searching for kinematic substructure, which can provide useful information about the underlying dark matter distribution in the Milky Way.

Speaker: Adriana Dropulic (Princeton University (US))

Dropulic_Pheno2021.pdf

14:15 → 16:00 Flavor I

Convener: Marco Guzzi (Kennesaw State University)

Zoom

14:15 Remarks on Direct CP in K, D and B decays

After decays of overcoming numerous challenging obstacles, first principles lattice methods recently reported a calculation by our RBC-UKQCD Collaboration [see R. Abbott et al, Phys.Rev. D102 (2020) no.5, 054509] of K to pi pi amplitudes and direct CP parameter epsilon’; also shedding light into the long-standing issue of the delta I=1/2 Rule. Wrt the experimental observation of direct CP in D0 decays, it is suggested that the neighboring resonances cause enhancements resulting in consistency of the experimental results with expectations from the SM. Lastly, while recent experimental progress in direct CP in B+ to K+ pi0 is an important step forward, it does not necessarily signify any anomalous behavior so long as reliable quantitative estimates canot be made of non-factorizable effects as well as of isospin violations given that isospin is not a symmetry of electroweak interactions.

Speaker: AMARJIT Soni (BNL)

4 Pheno 2021 final Dir CP.pdf

14:30 New physics in $b\rightarrow se^+e^-$: A model independent analysis

The lepton universality violating flavor ratios $R_K/R_{K^*}$ indicate new physics either in $b \to s \mu^+ \mu^-$ or in $b \to s e^+ e^-$ or in both. If the new physics is only $b \to s e^+ e^-$ transition, the corresponding new physics operators, in principle, can have any Lorentz structure. In this work, we perform a model independent analysis of new physics only in $b \to se^+e^-$ decay by considering effective operators either one at a time or two similar operators at a time. We include all the measurements in $b\rightarrow se^+e^-$ sector along with $R_K/R_{K^*}$ in our analysis. We show that various new physics scenarios with vector/axial-vector operators can account for $R_K/R_{K^*}$ data but those with scalar/pseudoscalar operators and with tensor operators can not. We also show that the azimuthal angular observable $P_1$ in $B \to K^* e^+ e^-$ decay is most suited to discriminate between the different allowed solutions.

Speaker: Suman Kumbhakar (IISc Bangalore)

talk.pdf

14:45 Measurement of the very rare K+→π+νν¯ decay

The NA62 experiment at CERN reports the branching ratio measurement BR(K+→π+νν) at 68% CL, based on the observation of 20 signal candidates with an expected background of 7.0 events from the total data sample collected at the CERN SPS during 2016-2018. This provides evidence for the very rare K+→π+νν decay, observed with a significance of 3.4σ. The experiment achieves a single event sensitivity of (0.839±0.054)×10−11, corresponding to 10.0 events assuming the Standard Model branching ratio of (8.4±1.0)×10−11. The result represents the most accurate measurement achieved so far of this ultra-rare decay. Future prospects and plans for data taking from 2021 will also be presented.

Speaker: Bob Velghe (TRIUMF (CA))

bvelghe_kpnn_pheno2021_v1.pdf

15:00 Lepton Flavor Universality in Y(3S) Decays to Tau Leptons and Muons with the BaBar Experiment

Lepton flavor universality in vector interactions is a robust prediction of the Standard Model, and deviations from universality would necessitate new physics. The recent hints of lepton flavor non-universality in $B$ meson decays highlight the importance of complementary probes of lepton flavor universality, including in decays of $\Upsilon$ mesons. We report on a recent precision measurement of the ratio of branching fractions BF($\Upsilon(3S) \rightarrow \tau^+ \tau^-$) / BF($\Upsilon(3S) \rightarrow \mu^+ \mu^-$) using a sample of 122 million $\Upsilon(3S)$ mesons collected with the BaBar detector. The uncertainties in this measurement improve on earlier studies by almost an order of magnitude, and are of comparable order to the deviations predicted in certain models of lepton non-universality in $B$ meson decays.

Speaker: Brian Shuve (Harvey Mudd College)

Y3SLFU_BaBar_Pheno2021_v3.pdf

15:15 Charmless $B$ decays at Belle II

Charmless $B$ decays provide a unique portion of the Belle II program. The expected large signal yields with moderate backgrounds associated with efficient reconstruction of neutral particles enable world-leading determination of the CKM phase $\alpha/\phi_2$, a conclusive understanding of the so-called K-$\pi$ CP puzzle, and further insight into the nature of localized CP violation in three-body decays. We report preliminary measurements based on the sample collected during 2019-2020 operations and corresponding to 65 fb$^{-1}$ of integrated luminosity. Results include a test of the $K\pi$ isospin sum-rule, an angular analysis of $B \to \rho^+ \rho^0$ decays, and the reconstruction of a $B^0 \to \pi^0\pi^0$ signal.

Speaker: Sebastiano Raiz (INFN - National Institute for Nuclear Physics)

PHENO_talk_Raiz.pdf

15:30 Tau physics prospects at Belle II

The Belle II experiment is a substantial upgrade of the Belle detector and will operate
at the SuperKEKB energy-asymmetric e+e− collider. The design luminosity of the machine
is 8 × 1035 cm−2s−1 and the Belle II experiment aims to record 50 ab−1 of data, a factor
of 50 more than its predecessor. From February to July 2018, the machine has completed a
commissioning run and main operation of SuperKEKB has started in March 2019. Belle II has
a broad τ physics program, in particular in searches for lepton flavour and lepton number
violations (LFV and LNV), benefiting from the large cross section of the pair wise τ
lepton production in e+e− collisions. We expect that after 5 years of data taking, Belle II
will be able to reduce the upper limits on LF and LN violating τ decays by an order of
magnitude. Any experimental observation of LFV or LNV in τ decays constitutes an unambiguous
sign of physics beyond the Standard Model, offering the opportunity to probe the underlying
New Physics. In this talk we will review the τ lepton physics program of Belle II.

Speaker: Güney POLAT (Aix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France)

PHENO2021_TauProspects_Polat.pdf

15:45 Rare Decays at LHCb

Rare b-hadron decays are sensitive probes of New Physics through the study of branching fractions, angular observables, CP asymmetries.The LHCb experiment is ideally suited for the analysis of these decays due to its high trigger efficiency, as well as excellent tracking and particle identification performance. Recent results from the LHCb experiment are presented and their interpretation is discussed.

Speaker: Ms Yanting Fan (University of Chinese Academy of Sciences (CN))

Pheno2021_raredecays.pdf

14:15 → 16:00 Tools I

https://pitt.zoom.us/j/93687648384

Convener: Tao Xu (Hebrew University)

zoom

14:15 Anomaly detection using machine learning

Speaker: David Shih (Rutgers University)

Shih_Pheno2021_AnomalyDetection.pdf

14:45 Nanosecond machine learning with BDT for high energy physics

We present a novel implementation of classification using boosted decision trees (BDT) on field programmable gate arrays (FPGA). The firmware implementation of binary classification requiring 100 training trees with a maximum depth of 4 using four input variables gives a latency value of about 10ns. Two problems are presented, in the separation of electrons vs. photons and in the selection of vector boson fusion-produced Higgs bosons vs. the rejection of the multijet processes. Implementations such as these enable the level-1 trigger systems to be more sensitive to new physics at high energy experiments. The work is described in [2104.03408].

Speaker: Tae Min Hong (University of Pittsburgh (US))

TMHong20210524_Pheno_fwX_v2.pdf

15:00 Training a new generation of Scientists via Outreach and Prototype Building.

An incipient program in Cosmic Ray and Radiation Detection is based at the International Elementary Particle Laboratory. Such efforts include an integral program to seek young talents, motivate them to pursue a STEAM oriented career and professionally train them in novel detection techniques by means of a hands-on approach that involves building innovative prototypes.

During the pandemic, over 30 prototypes meant to be used for radiation detection with novel materials, including metals, ionic liquids, and such, were planned, designed, and built remotely. They are now being tested, assembled, and placed on operation jointly with students who participate in the program. These novel detectors seek to detect cosmic rays and other forms of radiation with efficient, compact, and safe detectors.

In the Outreach phase, a series of online seminars were established to reach young talented kids with the aim to interest them in STEAM-oriented Careers. Those seminars have reached to date, over 530,000 people from all over Latin America primarily in the ages of 13-24 years old. Speaker include Julián Félix, Juan Maldacena, Juan Estrada, Gastón Gutiérrez, Fernando Quevedo, Gabriela González, Matias Zaldarriaga, Alberto Rojo and José Manuel Sánchez Ron amongst others.

Speakers: Waleska Aldana Segura, Julian Felix (Universidad de Guanajuato)

Training a new generation of scientistspheno.pdf

Training a new generation of scientistspheno.ppsx

15:15 Explainable AI for ML Jet Taggers

A framework is presented to extract and understand decision-making information from a deep neural network classifier of jet substructure tagging techniques. The general method studied is to provide expert variables that augment inputs (“eXpert AUGmented” variables, or XAUG variables), then apply layerwise relevance propagation (LRP) to networks that have been provided XAUG variables and those that have not. The XAUG variables are concatenated to the classifier’s intermediate input to the final layer.The results show that XAUG variables can be used to interpret classifier behavior, increase discrimination ability when combined with low-level features, and in some cases capture the behavior of the classifier completely. The LRP technique can be used to find relevant information the network is using, and when combined with the XAUG variables, can be used to rank features, allowing one to find a reduced set of features that capture a majority of network performance. These identified XAUG variables can also be added to low-level networks as a guide to improve performance.
*This work was supported under NSF Grants PHY-1806573, PHY-1719690 and PHY-1652066. Computations were performed at the Center for Computational Research at the University at Buffalo.

Speaker: Lauren Meryl Hay (SUNY Buffalo)

XAI_ML_PHENO.key

XAI_ML_PHENO.pdf

15:30 Mass Unspecific Supervised Tagging (MUST) for boosted jets

Jet identification tools are crucial for new physics searches at the LHC and at future colliders. We introduce the concept of Mass Unspecific Supervised Tagging (MUST) which relies on considering both jet mass and transverse momentum varying over wide ranges as input variables - together with jet substructure observables - of a multivariate tool. This approach not only provides a single efficient tagger for arbitrary ranges of jet mass and transverse momentum, but also an optimal solution for the mass correlation problem inherent to current taggers. By training neural networks, we build MUST-inspired generic and multi-pronged jet taggers which, when tested with various new physics signals, clearly outperform the variables commonly used by experiments to discriminate signal from background. These taggers are also efficient to spot signals for which they have not been trained. Taggers can also be built to determine, with a high degree of confidence, the prongness of a jet, which would be of utmost importance in case a new physics signal is discovered.

Speaker: Mr João Seabra (Departamento de Física and CFTP, Instituto Superior Técnico, Universidade de Lisboa)

MUST_PHENO2021.pdf

MUST_PHENO2021.pptx

15:45 Automating Boosted Decision Tree Analyses with MInOS

A new software tool MInOS (Machine Intelligent Optimization of Significance) is introduced for the automation of machine learning on collider event statistics, with back-end functionality provided by the XGBoost package. A simple, compact, and powerful meta-language syntax facilitates the generation of sophisticated Boosted Decision Tree analyses based upon instructions supplied in a reusable card file. MInOS integrates transparently with MadGraph/Pythia/Delphes and handles the weighted recombination and over-sampling of simulated data. All event statistics computable by the companion package AEACuS (and arbitrary user-supplied functions thereof) may be leveraged as learning keys, or as criteria for manual event selection. Ensemble training against distinct background components may be combined to generate composite classifications with enhanced discrimination, and trained models may be stored or converted into standalone executable code for reapplication. ROC curves as well as score distribution, feature importance, and significance threshold plots are generated on the fly.

Speaker: Prof. Joel Walker (Sam Houston State University)

MInOS_PHENO_21.pdf

16:00 → 16:30 Coffee Break

16:30 → 18:45 Axions & ALPs II

Zoom link Axions & ALPs II

16:30 Search for feebly interacting particles with NA62

The high-intensity setup and detector performance make the NA62 experiment at CERN particularly suited for searching new physics effects from different scenarios involving feebly interacting particles in the MeVGeV mass range.
A search for the K+→π+X decay, where X is a long-lived feebly interacting particle, is performed through an interpretation of the K+→π+νν¯ analysis of data collected in 2017-2018. Model- dependent upper limits are obtained assuming X to be an axion-like particle with dominant fermion couplings or a dark scalar mixing with the Standard Model Higgs. Upper limits set on the branching ratio BR(K+→π+X) improve on current limits for mX below 260 MeV/c2 and rest lifetimes above 100 ps.
A search for K+→μ+νX, where X is a massive invisible particle, is performed using the 2016-2018 data set. The X particle is considered a scalar or vector hidden sector mediator decaying to an invisible final state. Upper limits of the decay branching fraction for X masses in the range 10-370 MeV/c2 are reported for the first time, ranging from O(10−5) to O(10−7).
A study of a sample of 4×10ˆ9 tagged π0 mesons from K+→π+π0(γ) is performed, searching for the decay of the π0 to invisible particles. No signal is observed in excess of the expected background fluctuations. An upper limit of 4.4×10−9 is set on the branching ratio at 90% C.L. improving on previous results by a factor of 60.

Speaker: Roberta Volpe (Comenius University)

PHENO2021_VolpeR.pdf

16:45 Heavy Axion at DUNE

While the QCD axion is often considered to be necessarily light (eV), recent work has opened a viable and interesting parameter space for heavy axions, which solve both the Strong CP and the axion Quality Problems. These well-motivated heavy axions, as well as the generic axion-like-particles, call for explorations in the GeV mass realm at collider and beam dump environments. The primary upcoming neutrino experiment, Deep Underground Neutrino Experiment (DUNE), is simultaneously also a powerful beam dump experiment, enabled by its multipurpose Near Detector (ND) complex. In this study, we show with detailed analyses that the DUNE ND has a unique sensitivity to heavy axions for masses between 20 MeV and 2 GeV, complementary to other future experiments.

Speaker: Zhen Liu (University of Minnesota)

3_ALP_ZhenLiu_Pheno_2021.pdf

17:00 ALP Searches at Neutrino and Dark Matter Frontier Experiments

Axion-like particles (ALPs) provide a promising direction in the search for new physics, while a wide range of models incorporate ALPs. We point out that neutrino and dark matter experiments, such as DUNE and CCM, possess competitive sensitivity to ALP signals. High-intensity proton beams can not only produce copious amounts of neutrinos, but also cascade photons that are created from charged particle showers stopping in the target. Therefore, ALPs interacting with photons can be produced (often energetically) with high intensity via the Primakoff effect $\gamma Z \rightarrow a Z$ and then leave their signatures via inverse Primakoff scattering or decays to photon pairs, $a \rightarrow \gamma \gamma$. The proton beam may also induce an electron flux, which, together with the cascade photons, can produce ALPs via their couplings to electrons through bremsstrahlung-like and compton-like processes. Through this coupling, ALP detection via decays to $e^+ e^-$ and inverse compton scattering $a e^- \rightarrow \gamma e^-$ are also possible.
.

Speaker: Adrian Thompson (Texas A & M University)

thompson_pheno2021.pdf

17:15 Challenges for an axion explanation of the muon g−2 measurement

The discrepancy between the muon g−2 measurement and the Standard Model prediction points to new physics around or below the weak scale. It is tantalizing to consider the loop effects of a heavy axion (in the general sense, also known as an axion-like particle) coupling to leptons and photons as an explanation for this discrepancy. We provide an updated analysis of the necessary couplings, including two-loop contributions, and find that the new physics operators point to an axion decay constant on the order of 10s of GeV. This poses major problems for such an explanation, as the axion couplings to leptons and photons must be generated at low scales. We outline some possibilities for how such couplings can arise, and find that these scenarios predict new charged matter at or below the weak scale and new scalars can mix with the Higgs boson, raising numerous phenomenological challenges. These scenarios also all predict additional contributions to the muon g−2 itself, calling the initial application of the axion effective theory into question. We conclude that there is little reason to favor an axion explanation of the muon g−2 measurement relative to other models postulating new weak-scale matter.

Speaker: Dr Chen Sun (Brown University/ CAS-ITP)

g-2_ChenSun_Pheno2021.pdf

17:30 Heavy QCD Axion in b→s transition

I will talk about a ``heavy'' QCD axion whose coupling to the standard model is dominated by $a G \widetilde{G}$ but with $m_a \gg m_\pi f_\pi / f_a$. This is well motivated as it can solve the strong CP problem while evading the axion quality problem. Such axion with mass around a GeV is kinematically inaccessible or poorly constrained by most experimental probes except B-factories. We study $B \to K a$ transitions as a powerful probe of the heavy QCD axion by performing necessary 2-loop calculations for the first time, together with some improvement on the existing analysis strategy. We find some of the existing limits are enhanced by at least an order of magnitude. For forthcoming data sets of the Belle II experiment, we provide a projection that $f_a$ of a few TeV is within its future reach, which is relevant to the quality problem.

Speaker: Vazha Loladze (Florida State University)

Pheno21.pdf

17:45 Probing axion-like particles with 𝛾𝛾 final states from vector boson fusion processes at the LHC

Axion-like particles (ALPs) are pseudo-Nambu-Goldstone bosons of spontaneously broken global symmetries in theories attempting to address the incompleteness of the Standard Model (SM). In particular, ALPs arise in theoretical resolutions to the strong CP problem, offer explanations for the dark matter (DM) relic abundance, and are ubiquitous in string theory. The ALP mass $m_a$ can range from eV to TeV scale, and thus the ALPs parameter space includes regions relevant to a variety of astronomical, high-precision low-energy, and high-energy collider experiments. The focus of this talk is a feasibility study searching for ALPs using vector boson fusion (VBF) processes at the Large Hadron Collider (LHC). We consider the $a \to \gamma\gamma$ decay mode to show that the requirement of an energetic diphoton pair combined with two forward jets with large dijet mass and pseudorapidity separation can significantly reduce the SM backgrounds, leading to a 5$\sigma$ discovery region spanning $m_a$ values from MeV scale to TeV scale and revealing LHC sensitivity to previously unstudied regions of the ALP parameter space.

Speaker: Elijah Sheridan (Vanderbilt University)

sheridan_pheno_slides.pdf

18:00 Axions and scalars in neutron star mergers

While supernovae and cooling neutron stars have long been fruitful environments for constraining dark sector particles such as axions, neutron star mergers offer a novel territory to explore BSM physics and look for its signatures in the electromagnetic and gravitational wave signals from the merger. Axions interact weakly with hot, dense nuclear matter and therefore will escape from the merger remnant, cooling it. We find that significant cooling can occur on the timescales relevent for neutron star mergers. Other BSM particles, within current constraints on their parameters, may be trapped inside the merger remnant, perhaps contributing significantly to thermal equilibration of the nuclear matter in the remnant. We calculate the timescale of thermal equilibration due to a trapped gas of CP-even scalar particles inside a merger remnant.

Speaker: Steven Harris (Washington University in St. Louis)

Pheno_2021.pdf

18:15 Top quark production in association with additional particles at CMS: tt+bb, tt+cc, ttZ, ttW, ttgamma, tZ and tttt production

Top quark production in association with additional particles at CMS: tt+bb, tt+cc, ttZ, ttW, ttgamma, tZ and tttt production

Speaker: David Walter (Deutsches Elektronen-Synchrotron (DE))

david_ttX_Pheno2021.pdf

16:30 → 18:45 BSM II

Convener: Ljiljana Morvaj (CERN)

zoom

16:30 Third-generation leptoquark searches in CMS

Third-generation leptoquarks are considered the most viable particles that explain anomalous ratios of decays to different lepton flavors seen in B decays. In this talk, we present several recent results, including a new search for leptoquark pair production, as well as single-leptoquark and t-channel production for leptoquarks that couple strongly to third-generation particles.

Speaker: Izaak Neutelings (Universitaet Zuerich (CH))

LQ3_Pheno2021_Izaak_Neutelings_20210524.pdf

16:45 Search for heavy resonances in boosted jet plus MET final state in CMS

We present the search for heavy resonances decaying to a pair of bosons, WZ or ZZ, where one Z decays to a pair of neutrinos, and the other W or Z boson decays to a merged jet due to the boost. At the LHC these resonances can be produced through quark/anti-quark annihilation, gluon-gluon fusion, or weak vector boson fusion (VBF) processes. Tagging techniques for both forward jets produced in the VBF process and for identifying quarks from W/Z decays which fragment into a merged jet will be discussed. Challenges to traditional semi-visible resonance search techniques, which arise from a confluence of polarization effects and a partially reconstructed final state, will be presented. Finally, recent results in the context of scenarios beyond the standard model using LHC Run-2 datasets with the CMS detector will be given.

Speaker: Kamal Lamichhane (Texas Tech University (US))

ZV-CMS-Pheno-2021.pdf

17:00 Searches for heavy resonances decaying into Z, W, and Higgs bosons at CMS

We present a summary of searches for new heavy resonances decaying into pairs or triplets of bosons, performed on proton-proton collision data collected with the CMS detector at the CERN LHC at a center-of-mass energy of 13 TeV. A common feature of these analyses is the boosted topology, namely the decay products of the considered bosons (both electroweak W, Z bosons and the Higgs boson) are expected to be highly energetic and close in angle, leading to a non-trivial identification of the quarks and leptons in the final state. The exploitation of jet substructure techniques allows to increase the sensitivity of the searches where at least one boson decays hadronically. Various background estimation techniques are adopted, based on data-MC hybrid approaches or relying only in control regions in data. Results are interpreted in the context of multiple scenarios beyond the standard model.

Speaker: Xudong Lyu (Peking University (CN))

pheno2021_XudongLyu.pdf

17:15 Bounds on Gauge Bosons Coupled to Non-conserved Currents

We discuss new bounds on vectors coupled to currents whose non-conservation is due to mass terms, such as $U(1)_{L_\mu - L_\tau}$. In scenarios with Stueckelberg masses for such gauge bosons, due to the emission of many final state longitudinally polarized gauge bosons, inclusive rates grow exponentially fast in energy, leading to strong constraints. We present bounds coming from the high invariant mass tail of di-lepton events at the LHC, which beat out cosmological bounds to place the strongest limit on Stueckelberg $U(1)_{L_\mu - L_\tau}$ models for most masses below a keV. We also discuss a stronger, but much more uncertain, bound coming from the validity of perturbation theory at the LHC.

Speaker: Soubhik Kumar (UC Berkeley)

unitarity_pheno21_SK.pdf

17:30 New bounds on sneutrino masses through collider searches

Though collider searches are constraining supersymmetric parameter space, generic model independent bounds on sneutrinos remain very low. We calculate new model independent lower bounds on general supersymmetric scenarios with sneutrino LSP and NLSPs. By recasting ATLAS LHC exotic searches in mono boson channels, we place an upper bound on the cross section on $pp\rightarrow\tilde{\nu}\tilde{\nu}+V$ processes in mono-photon, mono-$Z$ and mono-Higgs channels. We also evaluate the LHC discovery potential of sneutrinos in the HL-LHC 3 $ab^{-1}$ run.

Speaker: Humberto Gilmer (Ohio State University)

pheno_2021-Gilmer.pdf

17:45 tZ' production at hadron colliders

We present a study of the production of a single top quark in association with a
heavy extra Z′ at hadron colliders in new physics models with and without flavor-changing neutral-current (FCNC) couplings. We use QCD soft-gluon resummation and threshold expansions to calculate higher-order corrections for the total cross section and transverse-momentum distributions for tZ′ production. The impact of uncertainties due to the structure of the proton and scale dependence is also discussed.

Speaker: Dr Marco Guzzi (Kennesaw State University)

PHENO2021-mguzzi.pdf

PHENO2021-mguzzi.pdf

PHENO2021-mguzzi.pptx

18:00 Search for new resonances coupling to third generation quarks at CMS

We present an overview of searches for new physics with top and bottom quarks in the final state, using proton-proton collision data collected with the CMS detector at the CERN LHC at a center-of-mass energy of 13 TeV. The results cover non-SUSY based extensions of the SM, including heavy gauge bosons or excited third generation quarks. Decay channels to vector-like top partner quarks are also considered. We explore the use of jet substructure techniques to reconstruct highly boosted objects in events, enhancing the sensitivity of these searches.

Speaker: James William Dolen (Purdue University Northwest (US))

PHENO 2021 - 2021 May - v3.pdf

18:15 ATLAS Searches for Resonances Decaying to Boson Pairs

Many extensions to the Standard Model predicts new particles decaying into two bosons (W, Z, photon, or Higgs bosons) making these important signatures in the search for new physics. Searches for such diboson resonances have been performed in final states with different numbers of leptons, photons, as well as jets and b-jets where new jet substructure techniques are used to disentangle the hadronic decay products in highly boosted configuration. This talk summarises recent ATLAS searches with Run 2 data collected at the LHC.

Speaker: Enrico Junior Schioppa (INFN Lecce e Universita del Salento (IT))

schioppa_pheno2021_v3.pdf

18:30 Searches for new physics in events with jets in the final state in CMS

Searches for new physics in events with jets in the final state in CMS

Speaker: Xuli Yan (Brown University (US))

Pheno21_XuliYan.pdf

16:30 → 18:45 BSM VII

Convener: Christian Herwig (Fermi National Accelerator Lab. (US))

zoom

16:30 The REDTOP experiment: An $\eta$/$\eta$' factory to explore BSM physics

The recent results from the LHC suggest that the next search for New Physics should be performed in the low-energy mass range using high-intensity beams. That has revived the interest in the phenomenology of new light particles with feeble interactions with the Standard Model[1]. The DOE in the US is perfectly positioned for that quest with four laboratories (FNAL, ORNL, BNL, and LANL) capable of providing intense proton beams in the 1 - 10 GeV energy range. Light dark matter must be neutral under SM charges, otherwise it would have been discovered at previous colliders[2]. The only known particles with all-zero quantum numbers are the $\eta$/$\eta$' mesons and the Higgs boson. They provide an excellent laboratory to search for New Physics. An $\eta$ factory is within the reach of each of the four aforementioned laboratories.
The REDTOP experiment is being designed to produce $10^{13}$ $\eta$ mesons and $10^{11}$ $\eta$' mesons. Two different production mechanisms are available, depending on the energy and intensity of the beam. The physics sectors which can be probed at REDTOP range from the violation of discrete symmetries to the search for new particles. Non-eta meson sectors can also be explored, such as ALPS and QCD-axions. Finally, the Standard Model can be probed at low energy at an unprecedented level. Novel detector techniques needs to be developed to cope with the high interaction rate. Future High Energy and High Intensity experiments will benefit from that R&D. A collaboration has been forming since several years with the intent of submitting a proposal to the US HEP Community.

[1] J. Alexander et al., Dark Sectors 2016 Workshop: Community Report, 2016, http://inspirehep.net/record/1484628/files/arXiv:1608.08632.pdf
[2] https://indico.fnal.gov/event/44819/contributions/193751/attachments/132857/163535/RF6-Kickoff-DM-Production.pdf

Speaker: Corrado Gatto (INFN & NIU)

Pheno2021_REDTOP.pdf

Pheno2021_REDTOP.pptx

16:45 FASER: Forward Search Experiment at the LHC

The FASER experiment is a new small and inexpensive experiment that is being placed 480 meters downstream of the ATLAS experiment at the CERN LHC. The experiment will shed light on currently unexplored phenomena, having the potential to make a revolutionary discovery. FASER is designed to capture decays of exotic particles, produced in the very forward region, out of the ATLAS detector acceptance. This talk will present the physics prospects, the detector design, and the construction progress of FASER. The experiment has been successfully installed and will take data during the LHC Run-3.

Speakers: Benedikt Vormwald (CERN), FASER Collaboration

20210524_faser_pheno2021.pdf

17:00 Multi-TeV Signals of Baryogenesis in Higgs Troika Model

A modest extension of the Standard Model by two additional Higgs doublets - the Higgs Troika Model - can provide a well-motivated scenario for successful baryogenesis if neutrinos are Dirac fermions. Adapting the "Spontaneous Flavor Violation" framework, we consider a version of the Troika model where light quarks have significant couplings to the new multi-TeV Higgs states. Resonant production of new scalars leading to di-jet or top-pair signals are typical predictions of this setup. The initial and final state quarks relevant to the collider phenomenology also play a key role in baryogenesis, potentially providing direct access to the relevant early Universe physics in high energy experiments. Viable baryogenesis generally prefers some hierarchy of masses between the observed and the postulated Higgs states. We show that there is a complementarity between direct searches at a future 100 TeV $pp$ collider and indirect searches at flavor experiments, with both sensitive to different regions of parameter space relevant for baryogenesis. In particular, measurements of $D-\bar{D}$ mixing at LHCb probe much of the interesting parameter space. Direct and indirect searches can uncover the new Higgs states up to masses of $\mathcal{O}(10)$ TeV, thereby providing an impressive reach to investigate this model.

Speaker: Dr Matthew Sullivan (Brookhaven National Laboratory)

HiggsTroika.pdf

17:15 A New Approach to Electroweak Symmetry Non-Restoration

Electroweak symmetry non-restoration up to high temperatures well above the electroweak scale has intriguing implications for (electroweak) baryogenesis and early universe thermal histories. In this talk, I will discuss a new approach for electroweak symmetry non-restoration via an inert Higgs sector that couples to the Standard Model Higgs as well as an extended scalar singlet sector. Examples of benchmark scenarios that allow for electroweak symmetry non-restoration all the way up to hundreds of TeV temperatures, featuring suppressed sphaleron washout factors down to the electroweak scale, will be presented. Renormalization group improvements and thermal resummation, necessary to evaluate the effective potential spanning over a broad range of energy scales and temperatures, have been implemented calculating the thermal history. This method for transmitting the Standard Model broken electroweak symmetry to an inert Higgs sector can be scrutinized through Higgs physics phenomenology and electroweak precision measurements at the HL-LHC.

Speaker: Yikun Wang (THE UNIVERSITY OF CHICAGO)

pheno21_EWNR_pub.pdf

17:30 Detecting New Physics as Novelty

Novelty detection is a task of Machine Learning to detect novel events without a prior knowledge. Its techniques can be applied to detect unexpected signals of new physics at colliders. We generalize the complementary strategies developed in the paper (arxiv:1807.10261) for achieving this task. Generally, the novelty evaluators are classified into two categories: isolation-based and clustering (density)-based. Properly combining the evaluators from each category yields a third category, namely "synergy-based", which may significantly improve the efficiency and quality of novelty evaluation. We demonstrate these features by analyzing the performances of the three category of evaluators, using a variety of two dimensional Gaussian samples mimicking collider events. This study is subsequently applied to the LHC detection of the $t\bar th$ Higgs physics and the gravity-mediated supersymmetry as novel events in the $t\bar t\gamma\gamma$ channel. These two scenarios represent the signal patterns with a sharp resonance and a broad distribution of $m_{\gamma\gamma}$, respectively. The sensitivities at detector level are provided, which read encouraging compared to the ongoing LHC analysis.

Speaker: Mr Xuhui JIANG (The Hong Kong University of Science and Technology)

Detecting_NP_as_Novelty_pheno2021.pdf

17:45 Simplifying Multidimensional Constraints on Narrow Resonances

The simplified limits framework is an approach developed to recast limits on searches for narrow resonances in terms of products of branching ratios (BRs) corresponding to the resonance's production and decay modes. In this talk, we will present an extension of the framework to a multidimensional parameter space of BRs. This can be used in a model-independent way to unfold an ambiguity in the simplified parameter $\zeta$ introduced when more than one channel contributes to the production of the resonance, and is naturally applicable to combining constraints from experimental searches with multiple observed final states. These constraints are visualized in a three-dimensional space of branching ratios by employing ternary diagrams, triangle plots which utilize the inherent unitarity of the sum of the resonance's BRs. We will briefly discuss the broader application of N-simplexes to parameterize and store digital data sets.

Speaker: James Osborne (UC San Diego)

JOsborne_Pheno21.pdf

18:00 The Higgs of Baryon Number and Dark Matter

I will discuss the correlation between dark matter and Higgs decays in gauge theories where the dark matter is predicted from anomaly cancellation. In these theories, the Higgs responsible for the breaking of the gauge symmetry generates the mass for the dark matter candidate. We investigate the Higgs decays in the minimal gauge theory for Baryon number. After imposing the dark matter density and direct detection constraints, we find that the new Higgs can have a large branching ratio into two photons or into dark matter. Furthermore, we discuss the production channels and the signatures at the Large Hadron Collider

Speaker: Alexis Plascencia (Case Western Reserve University)

Alexis_Plascencia.pdf

18:15 Probe Light Scalars in 2HDMs at FASER

Two Higgs Doublet Model (2HDM) offers a prototype beyond the Standard Model (SM) with an extended Higgs sector. It provides a rich spectrum of scalars, of which some can be relatively light with weak couplings to the SM particles. Complementary to the usual searches for extra scalars at high energy colliders, FASER offers a unique opportunity to study those relatively long-lived light scalars. Given all the existing theoretical and experimental constraints, we consider the light CP-even and CP-odd scalars in the four different types of 2HDMs, and examine the parameter window which can be probed at FASER.

Speaker: Huayang Song (University of Arizona)

2HDM@Faser.pdf

18:30 Results on rare and new top quarks interactions, including EFT, in CMS

Results on rare and new top quarks interactions, including EFT, in CMS

Speaker: Clara Ramon Alvarez (Universidad de Oviedo (ES))

Pheno2021.pdf

16:30 → 18:45 Cosmology II

https://pitt.zoom.us/j/96734791723

Zoom

16:30 A proposal for relative in-flight flux self-calibrations for spectro-photometric surveys

Cosmology experiments are often based on large-scale surveys on satellite and need methods to perform in-flight relative flux self-calibrations of their spectro-photometer instruments. In this talk a method is proposed where the instrument response function is inferred with a chi square statistics in an unbiased way, simulating a simplified sequence of observations with realistic distributions of sources and count rates. A validation of the method, with the definition of figures of merit to quantify the expected performances, will also be presented.

Speaker: Silvano Tosi (INFN e Universita Genova (IT))

TalkPheno2021_Tosi.pdf

16:45 A Dark Sector to Restore Cosmological Concordance

There are currently tensions between observations of the early and late Universe in the determination of the cosmological parameters $S_8$ and $H_0$. In this talk, I will discuss a new phenomenological model that addresses these tensions. Our scenario features: (i) a decaying dark energy fluid, which undergoes a transition at $z \sim 5,000$, to raise today's value of the Hubble parameter -- addressing the $H_0$ tension, and (ii) an ultra-light axion, which starts oscillating at $z\sim 16,000$, to suppress the matter power spectrum -- addressing the $S_8$ tension. Our Markov Chain Monte Carlo analyses show that such a Dark Sector model fits a combination of early time datasets slightly better than the $\Lambda$CDM model, while reducing both the $H_0$ and $S_8$ tensions to $ <\sim3\sigma$ level. Combined with measurements from cosmic shear surveys, we find that the discrepancy on $S_8$ is reduced to the $1.4\sigma$ level, and the value of $H_0$ is further raised. Adding local supernovae measurements, we find that the $H_0$ and $S_8$ tensions are reduced to the $1.5\sigma$ and $1.1\sigma$ level respectively, with a significant improvement $\Delta\chi^2\simeq -17$ compared to the $\Lambda$CDM model. A particle physics realization of this model could be found in a dark confining gauge sector and its associated axion, although embedding the full details within microphysics remains an urgent open question. This scenario will be decisively probed with future CMB surveys. This talk is based on Ref. 2104.12798.

Speaker: Itamar Allali

PHENO2021_HubbleDarkSector.pdf

17:00 Massive Neutrino Self-interactions and The Hubble Tension

Based on: JCAP 03 (2021) 084 (arXiv: 2012.07519)
We have updated the constraints on flavor universal neutrino self-interactions mediated by a heavy scalar, in the effective 4-fermion interaction limit. Based on the latest CMB temperature data from the Planck 2018 data release as well as auxiliary data we confirm the presence of a region in parameter space with relatively strong self-interactions which provides a better than naively expected fit. However, we also find that the most recent data, in particular high-ℓ polarisation data from the Planck 2018 release, disfavors this solution even though it cannot yet be excluded. Our analysis takes into account finite neutrino masses (parameterized in terms of $\sum m_{\nu}$) and allows for a varying neutrino energy density (parameterized in terms of $N_{\rm eff}$), and we find that in all cases the neutrino mass bound inferred from cosmological data is robust against the presence of neutrino self-interactions. Finally, we also find that the strong neutrino self-interactions do not lead to a high value of $H_0$ of around 73 km/s/Mpc being preferred as long as CMB high-ℓ polarisation data from the Planck 2018 is included, i.e. this model does not seem like a viable solution to the current $H_0$ discrepancy.

Speaker: Shouvik Roy Choudhury (Indian Institute of Technology Bombay)

Talk.pdf

17:15 Hubble tension with an extra radiation and neutrino degeneracy

The standard Lambda CDM cosmological model now seems to face some puzzles. One of the most serious problems is the so-called Hubble tension; the values of the Hubble constant obtained by local measurements look inconsistent with that inferred from CMB. Although introducing extra radiations $\Delta N_{\textrm{eff}}$ such as hot axions or sterile neutrinos appears to be promising, such extra radiations increase the Helium mass fraction synthesized by Big Bang Nucleosynthesis (BBN). To cancel such an increment, positive electron neutrino asymmetry $\xi_{e}$ may be also needed. By analysing the data from Planck, baryon acoustic oscillation (BAO), BBN and type-Ia supernovae, we evaluate the possibility of the non-zero lepton asymmetry and extra radiations.

Speaker: Yo Toda

17:30 Quasars as New Standard Candles

A previous analysis of light curves from 13 quasars in the MACHO survey has shown some cor-relation among short time scale variations. Particularly, in the quasar’s rest frame, linear segments over time scales on the order of 100 days indicate a common slope. Though the source of this feature is at present unknown, such a commonality could allow one to determine the relative redshift of one quasar to another by comparing light curves thereby adding another benchmark to the cosmic distance ladder. We here extend the previous analysis to the remaining 46 well-sampled quasars in the MACHO survey and an additional∼9200 under-sampled quasars from the Sloan Digital Sky Survey. The feature proves to be persistent among the majority of quasars but requires the sampling rate of the quasar to be on average once every 15 days to reliably estimate the redshift.

Speaker: Rance Solomon

PHENO2021_pres.pdf

17:45 Linking the supersymmetric standard model to the cosmological constant

In string theory picture, Planck scale $M_{\rm Pl}$, the supersymmetry-breaking scale $m_s$, electroweak scale $m_{\rm EW}$ and vacuum energy density (cosmological constant) $\Lambda$ are to be dynamically determined from string scale $M_S$. Here we consider a model that links the supersymmetric electroweak phenomenology to string theory motivated flux compactification approach. The model breaks supersymmetry through a combination of the racetrack K\"ahler uplift mechanism and anti-D3-brane in the KKLT. The introduction of the Higgs field allows a small $\Lambda$ and a big $m_s$ simultaneously.

Speaker: Yucheng QIU (The Hong Kong University of Science and Technology)

Pheno_2021_QIU_yucheng.pdf

18:00 String-inspired Infinite Derivative Non-local QFT: Non-perturbative results

Non-local quantum field theories have been studied recently as a promising approach to go beyond the Standard Model (e.g. see [1–3]). This approach is strongly motivated by string theory (p-adic string field theory) [4–6]. These theories have the properties of UV-completeness and (proposed as a direction of UV-completion the non-local inifinte-derivative theories) are ghost-free (re-normalizable and predicts conformal invariance at the quantum level) [7]. They are able to rescue dark matter models [3], move trans-planckian processes to sub-planckian [8] and improve inflationary behaviour of the Higgs field [9]. On the same research avenues, we consider an infinite derivative scalar field theory and we show, by a technique devised by Bender, Savage and Milton [10], how to derive the set of Dyson-Schwinger equations in differential form. Then, we provide a method to solve them, assuming that non-local effects are small at low-energies and taking into account only the leading order solutions [11]. Local solutions for the scalar field theory, both for the classical and the quantum case have been recently obtained [12–15] and can be applied also to the solution of the Yang-Mills theory [16] and confinement studies can be accomplished with Kugo-Ojima crtierion properly generalized [17]. It is seen that UV-limit is never reached in this cse. In these studies, we just assume that they represent the local solutions to start from to get the corrections due to the non-locality. An immediate consequence of this approach is that the a mass gap is obtained and the spectrum of the theory becomes computable. In any case, the mass gap is diluted and these theories become conformal in the UV-limit. By analogy, also the graviton propagator possibly would get a mass gap that is diluted in the UV-limit reaching a conformal limit.

Speaker: Dr Marco Frasca

Pheno2021_Frasca.pdf

18:15 Post-Minkowskian Spinning Binary Dynamics in the Worldline Effective Field Theory Approach

The worldline effective field theory formalism provides a systematic approach to probe the post-Minkowskian binary scattering processes. Expanding to include spin degrees of freedom, we compute the total change in momentum and spin in the gravitational scattering of compact objects to next-to-leading PM order with linear and bilinear spin effects and arbitrary initial conditions. Using the Boundary-to-Bound correspondence we construct the radial action for elliptic-like orbits for the aligned spin configurations.

Speaker: Zixin Yang (Deutsches Elektronen-Synchrotron DESY)

Pheno.pdf

18:30 The Hubble Constant in the Axi-Higgs Universe

The $\Lambda$CDM model provides an excellent fit to the CMB data. However, a statistically significant tension emerges when its determination of the Hubble constant $H_0$ is compared to the local distance-redshift measurements. The axi-Higgs model, which couples ultralight axions to the Higgs field, offers a specific variation of the $\Lambda$CDM model. It relaxes the $H_0$ tension as well as explains the $^7$Li puzzle in Big-Bang nucleosynthesis, the $S_8$ tension with the weak-lensing data, and the observed isotropic cosmic birefringence in CMB. In this letter, we demonstrate how the $H_0$ and $S_8$ tensions can be resolved simultaneously, by correlating the axion impacts on the early and late universe. In a benchmark scenario selected for experimental tests soon, the analysis combining the CMB+BAO+WL+SN data yields $H_0 = 71.1 \pm 1.1$ km/s/Mpc and $S_8 = 0.766 \pm 0.011$. Combining this (excluding the SN(supernovae) part) with the local distance-redshift measurements yields $H_0 = 72.3 \pm 0.7$ km/s/Mpc, while $S_8$ is unchanged.

Speaker: Hoang Nhan LUU (The Hong Kong University of Science and Technology)

LHN_Pheno2021.pdf

16:30 → 18:30 DM II

Convener: Nirmal Raj (TRIUMF)

Zoom link DM II

16:30 Stellar Shocks From Dark Asteroids

Dark matter could take the form of macroscopic objects, scattering on baryonic matter with geometric cross section. There is a wide "asteroid" mass range over which such objects are almost unconstrained. We show that when a dark asteroid travels through a star, it produces shock waves which reach the stellar surface, leading to a distinctive transient UV emission. In a dense globular cluster, such transients occur far more often than flare backgrounds, and an existing UV telescope could probe five orders of magnitude in dark matter mass in one day of observation.

Speaker: Kevin Zhou (Stanford University)

PHENO_DarkAsteroid.pdf

16:45 Celestial-Body Focused Dark Matter Annihilation Throughout the Galaxy

Indirect detection experiments typically measure the flux of annihilating dark matter (DM) particles propagating freely through galactic halos. We consider a new scenario where celestial bodies "focus" DM annihilation events, increasing the efficiency of halo annihilation. In this setup, DM is first captured by celestial bodies, such as neutron stars or brown dwarfs, and then annihilates within them. If DM annihilates to sufficiently long-lived particles, they can escape and subsequently decay into detectable radiation. This produces a distinctive annihilation morphology, which scales as the product of the DM and celestial body densities, rather than as DM density squared. We show that this signal can dominate over the halo annihilation rate in γ-ray observations in both the Milky Way Galactic center and globular clusters. We use \textit{Fermi} and H.E.S.S. data to constrain the DM-nucleon scattering cross section, setting powerful new limits down to ∼10^{−39} cm2 for sub-GeV DM using brown dwarfs, which is up to nine orders of magnitude stronger than existing limits. We demonstrate that neutron stars can set limits for TeV-scale DM down to about 10^{−47} cm2

Speaker: payel mukhopadhyay (Stanford University)

Pheno talk-2021.pdf

17:00 Where is a Miracle-less WIMP Ruled Out?

We examine a real electroweak triplet scalar field as dark matter, abandoning the requirement that its relic abundance is determined through freeze out in a standard cosmological history (a situation which we refer to as `miracle-less WIMP'). We extract the bounds on such a particle from collider searches, searches for direct scattering with terrestrial targets, and searches for the indirect products of annihilation. Each type of search provides complementary information, and each is most effective in a different region of parameter space. LHC searches tend to be highly dependent on the mass of the SU(2) charged partner state, and are effective for very large or very tiny mass splitting between it and the neutral dark matter component. Direct searches are very effective at bounding the Higgs portal coupling, but ineffective once it falls below $\lambda_{\text{eff}} \sim 10^{-3}$. Indirect searches suffer from large astrophysical uncertainties due to the backgrounds and $J$-factors, but do provide key information for $\sim$ 100 GeV to TeV masses. We determine the parameter space for this example of miracle-less WIMP dark matter that can be robustly excluded, and which parts of it remain viable.

Speaker: Jason Arakawa

Miracle-Less WIMP Presentation Final.pdf

17:15 Indirect Detection of Secluded Supersymmetric Dark Matter

Weak-scale secluded sector dark matter can reproduce the observed dark matter relic density via thermal freeze-out within that sector. If supersymmetric, three portals to the visible sector — a gauge portal, a Higgs portal, and a gaugino portal — are present. We present the gamma ray spectra relevant for indirect detection in these set-ups. Since R-parity is no longer necessary to ensure dark matter stability, we investigate the impact of R-parity violation on the annihilation spectra. We present limits from the Fermi Large Area Telescope (LAT) analysis of dwarf galaxies and projections for the Cherenkov Telescope Array (CTA) probe of the galactic center.

Speaker: Patrick Barnes (University of Michigan)

Pheno 2021.pdf

17:30 Optimal Observation Strategies for Velocity-Suppressed Dark Matter Annihilation

Numerous particle models for the cosmological dark matter feature a pair-annihilation rate that scales with powers of the relative velocity between the annihilating particles. As a result, the annihilation rate in the central regions of dark matter halo can be significantly lower than at the halo's periphery for particular ambient gravitational potentials. While this might be offset by an increasing dark matter pair number density in the inner halo, it raises the question: what angular region for dark matter models with velocity-suppressed annihilation rates optimizes signal-to-noise? Here, we consider simplified background models for galactic and extragalactic targets and demonstrate that the optimal observing strategy varies greatly case-by-case. Generally, a bright central source warrants an annular region of interest, while a flatter noise profile warrants as large as possible an angular region, possibly including the central regions.

Speaker: Nolan Smyth (University of California, Santa Cruz)

JFactorsPheno2021Smyth.pdf

17:45 Mirror Neutron Stars

The paradigm of neutral naturalness suggests the existence of highly non-minimal hidden sectors. In particular, the Mirror Twin Higgs model postulates that some of dark matter is in the form of mirror matter, featuring mirror quarks, leptons and gauge bosons whose masses are a few times heavier than their Standard Model counterparts. I will discuss the possibility that mirror matter could have coalesced into Mirror Neutron Stars, invisible cousins of ordinary neutron stars. I will show how the properties of Mirror Neutron Stars can be determined using repurposed Lattice QCD data, and discuss the gravitational wave signatures of Mirror Neutron Star mergers. Given the impressive reach of current and future gravitational wave detectors, gravitational wave astronomy may offer a novel and powerful means of detecting (or constraining) non-minimal dark sectors.

Speaker: Jack Setford (University of Toronto)

Mirror Neutron Stars.pdf

18:00 Indirect Detection Signatures of a Dark Glueball Spectrum

I report on an ongoing investigation of how a hidden ‘dark’ confining gauge sector, common in Hidden Valley models such as the Mirror Twin Higgs, could lead to novel signatures in indirect detection searches for dark matter. Dark matter annihilation can then lead to dark showers of multiple and various hadrons, distinct from particle pair production. If there are no light fermions charged under this force, the lightest hadrons are glueballs, a spectrum of a dozen metastable states that is reasonably well understood from lattice calculations. The lightest of these states, the $0^{++}$ glueball, can mix with the Higgs and decay through this portal into the Standard Model (SM). The decay of $0^{++}$ glueballs has been studied within the context of collider searches, as it is the shortest lived state, decaying on scales that can be observed as displaced vertices. However, since indirect detection methods probe astrophysical length and time scales, they are also sensitive to the decays of longer living glueball states that can decay into $0^{++}$ and SM particles; this leads to an increased multiplicity of particles such as positrons and antiprotons, but also possibly probes the properties of the entire glueball spectrum. Since the decays depend on the allowed operators, this may allow information on the UV completion of the sector to be determined. Understanding the possible indirect signatures and constraints of a pure glue gauge theory is especially relevant as the next generation of cosmic ray telescopes, such as GAPS, begin their searches.

Speaker: Caleb Gemmell (University of Toronto)

PHENO21_gemmell.pdf

18:15 Probing Baryonic Dark Matter Models with Gravitational Waves

Gravitational waves provide a unique method of testing theories with extended gauge symmetries. In particular, spontaneous symmetry breaking can lead to a detectable stochastic gravitational wave background generated by cosmic strings and first order phase transitions in the early universe. I will discuss the unique gravitational wave signature of a simple model with gauged baryon and lepton numbers, in which a high scale of lepton number breaking is motivated by the seesaw mechanism for the neutrinos, whereas a low scale of baryon number breaking is required by the observed dark matter relic density. This novel signature can be searched for in near-future gravitational wave experiments.

Speaker: Bartosz Fornal (University of Utah)

B_Fornal.pdf

16:30 → 18:45 Flavor II

https://pitt.zoom.us/j/95618235024

Convener: Zack Sullivan (Illinois Institute of Technology)

zoom

16:30 Complementary Probes of Lepton Flavor at a Muon Collider

Low energy probes of lepton flavor violation (LFV) are indirectly probing new physics beyond the TeV scale, with order of magnitude advances expected in the future. A high energy muon collider would have the reach to probe similar processes at higher energies, e.g., via 𝜇𝜇→𝜏𝜇, which can be compared to the low-energy flavor-violating decay bounds. Alternatively, in particular models of new physics, new particles with flavor-violating interactions can be produced directly, such as mixed slepton pair production in the MSSM. I’ll present some first estimates of the physics reach of a muon collider for both of these scenarios, with an emphasis on the complementarity between low-energy precision experiments and high-energy muon collider searches.

Speaker: Qianshu Lu

LFV_muon_collider_QianshuLU_Pheno2021.pdf

16:45 Getting chirality right: single scalar leptoquark solutions to the (g-2)_{e/mu} puzzle

We identify the two scalar leptoquarks capable of generating sign-dependent contributions to leptonic magnetic moments, 𝑅2∼(3,2,7/6) and 𝑆1∼(3,1,−1/3), as is a strong possibility given current measurements. We consider the case in which the electron and muon sectors are decoupled, and real-valued Yukawa couplings are specified using an up-type quark mass-diagonal basis. This allows us to identify a previously overlooked region of parameter space, where strong constraints from LFV decays may be avoided. We also comment on the viability of these simple models for studies of leptonic EDMs. This analysis can be embedded within broader flavour anomaly studies, including those of hierarchical leptoquark coupling structures.

Speaker: Innes Bigaran (The University of Melbourne)

Bigaran_Pheno21_Upload.pdf

17:00 Radiative M1 Decays of Heavy Flavor Baryons in Effective Mass Scheme

The M1 radiative transitions of heavy flavor baryons are studied in the framework of Effective Mass Scheme (EMS) within the quark model. The intent of the EMS lies in the fact that the masses of the quarks inside the baryon are modified as a consequence of one-gluon exchange interaction with the spectator quarks and it treats all the quarks at the same footing. The baryon mass can be written as the sum of the constituent quark masses and the spin-dependent hyperfine interaction
among them. We show that EMS can successfully describe the masses and the magnetic moments, transition moments, and radiative decay widths of the lowest-lying singly heavy flavor baryons in a parameter independent way. For the calculation of effective quark masses, the exchange contribution is worked out through interaction terms bij from the recently observed experimental masses for the heavy flavored charm and bottom baryons. We then compute the magnetic and transition moments of ground state J^P = (1/2)^(+) and J^P = (3/2)^(+), and(1/2)^('+) → (1/2)^(+), (3/2)^(+) → (1/2)^(+), and (3/2)^(+) → (1/2)^('+) heavy flavor charm and bottom baryon states. Finally, we make sturdy model independent predictions for radiative M1 decay widths of heavy flavored baryons. The radiative transitions between the states occur mainly through the M1-type, while there are negligible contributions from E2-type transitions, which are
therefore ignored. We also extend our analysis to the triply heavy charm and bottom baryons.

Speaker: Avijit Hazra (SRM Institute of Science and Technology)

Final_M1 Radiative Decays.pdf

M1 Radiative Decays.pdf

Radiative M1 decays.pdf

17:15 The re-discovery of the decays for the CP violation measurements

$\sin 2 \phi_1 ~(\sin 2 \beta)$ is measured using the $CP$-eigenstates induced by the $b \to c$ tree diagram and it is the most precise variable among the CKM angles.
We have presented the result of the measurement using the $B^0 \to J/\psi K^0_S$ decay collected from the early Belle II data. On the other hand, it can be measured also using the decays induced by $b \to s$ penguin diagram. In that case, contribution of the new physics is expected so that effective $\sin 2 \phi_1 \equiv \sin 2 \phi_1^{\rm eff}$ is measured. In relation to those measurements, we present the re-discoveries of the $B^0 \to J/\psi K^0_L$ and $B^0 \to \eta’ K^0_S$ decays using the data set obtained by the Belle II in 2019 and 2020. Former one is a good indicator to check the difference of $CP$ eigenvalue between $B^0 \to J/\psi K^0_S$. Latter one is one of the modes used for $\sin 2 \phi_1^{\rm eff}$ measurement and its branching fraction is relatively large.

Speaker: Chiara La Licata

PHENO2021_lalicata_final.pdf

17:30 The search for rare top production and decay processes with the ATLAS experiment at the LHC

Run 2 of the LHC has witnessed the observation of rare top quark production processes predicted by the Standard Model and has enabled searches for heavily suppressed flavour-changing-neutral-current interactions of the top quark. In this contribution the highlights are shown of searches by the ATLAS experiment for rare processes involving top quark. The associated top quark production processes of a top quark pair with Standard Model gauge bosons have been observed, as well as the tZq process, and provide tight constraints on the top quark electro-weak couplings. Recently, the ATLAS experiment has announced evidence for the four-top-production process, and has performed a combined measurement of the tttt cross section in the single-lepton, two-lepton and multi-lepton channels. Finally, results are presented of searches for flavour-changing-neutral-current processes involving top quarks.

Speaker: Anil Sonay (The Barcelona Institute of Science and Technology (BIST) (ES))

raretop_pheno2021_v2.pdf

17:45 Top quark precision measurements with the ATLAS experiment at the LHC

Run 2 of the Large Hadron Collider, with 140/fb of proton proton collisions at a center-of-mass energy of 13 TeV, has produced over 10^8 top quarks. The large sample has enabled precise measurements of the production cross section in the "classical" top quark production processes, as well as new measurements in previously unobserved kinematic regimes and production processes. In this contribution, precision measurements of top quark properties and interactions are reviewed, with emphasis on the recent highlights of the ATLAS top quark physics program.

Speaker: Alexander Basan (Johannes Gutenberg Universitaet Mainz (DE))

ATL-COM-PHYS-2021-233.pdf

18:00 Signatures of toponium formation in LHC run 2 data

Measurements in top-antitop events at the LHC unraveled some anomalies. We examine the possibility that those reflect some mismodeling in Standard Model top pair-production. While subdominant, so-far neglected toponium contributions yield the additional production of dileptonic systems of small invariant mass and small azimuthal angle separation, which could explain the anomalies. We propose a method to discover toponium in present and future data. This paves the way to further experimental and phenomenological studies, as understanding toponium effects is essential for precision measurements of one of the most important parameters of the Standard Model, the top mass.

Speaker: Ya-Juan Zheng

toponium.pdf

18:15 Vector boson plus heavy-flavor jets measurements at CMS

The vector bosons decaying into two same leptonic flavor and heavy-flavor jets have been studied using proton-proton collisions at the Large Hadron Collider with the CMS experiment. This study is important to test pQCD theory by comparing experimental cross section with theoretical predictions and to distinguish signal from the background in many SM processes and BSM searches. The kinematic properties have been compared with the prediction from several Monte Carlo event generators using different parton shower simulations.

Speaker: Meena Meena (Panjab University (IN))

V_HF_13TeV.pdf

18:30 ATLAS measurements of CP violation and rare decays processes with beauty mesons

The ATLAS experiment has performed measurements of B-meson rare decays proceeding via suppressed electroweak flavour changing neutral currents, and of mixing and CP violation in the neutral B meson systems.

This talk will focus on the latest results from the ATLAS collaboration, such as rare processes B^0_s → mu mu and B^0 → mu mu, and CP violation in the B_s^0 —> J/psi phi decays. In the latter, the Standard Model predicts the CP violating mixing phase, phi_s, to be very small and its SM value is very well constrained, while in many new physics models large phi_s values are expected. The latest measurements of phi_s and several other parameters describing the B_s^0 —> J/psi phi decays will be reported.

Speaker: Pavel Reznicek (Charles University (CZ))

Reznicek_RareBandCPV.pdf

16:30 → 18:45 Tools II

https://pitt.zoom.us/j/93687648384

Convener: Daneng Yang (Department of Physics, Tsinghua University (CN))

zoom

16:30 Criteria for projected discovery and exclusion sensitivities of counting experiments

The projected discovery and exclusion capabilities of searches are often quantified using the median expected $p$-value or its corresponding significance. However, this criterion can lead to flawed results, for example counterintuitively predicting lessened sensitivities if the experiment takes more data or reduces its background. We discuss the merits of several alternatives to the median expected significance, both when the background is known and when it is subject to some uncertainty. We advocate for standard use of the “exact Asimov significance” $Z^{\rm A}$ detailed in this talk.

Speaker: Stephen Martin (Northern Illinois University)

spmartin.pdf

16:45 Analysis of Bayesian estimates for missing higher orders in perturbative calculations

With current high precision collider data and high-order calculations, the reliable estimation of theoretical uncertainty due to missing higher orders (MHO) terms has become a pressing issue for perturbative QFT predictions. The traditionally used simple but ad hoc scale variation has no probabilistic interpretation. Bayesian approach to MHO introduced by Cacciari and Houdeau and recently extended by Bonvini offers a promising alternative. In this paper, we thoroughly scrutinize the Bayesian approach and systematically study the performance of different models on an extensive set of high-order calculations.We extend the framework in two significant ways. First, we define three-parameter $abc$-model to allow for asymmetric probability distributions. Secondly, we calculate MHO uncertainty for scale-dependent quantities, treating different choices of the factorization and regularization scales democratically, without the hidden parameter interpretation à la Bonvini. We clarify how these two choices bias the result towards specific scale values. Finally, we provide a practical prescription of how existing perturbative results at the standard scale variation points can be converted to 68 %/95 % confidence intervals in the Bayesian approach.

Ref.: Claude Duhr, Alexander Huss, Aleksas Mazeliauskas, and Robert Szafron, to appear soon.

Speaker: Dr Aleksas Mazeliauskas (CERN)

mazeliauskas_PHENO.pdf

17:00 Triggering on electrons and photons in CMS in Phase2 and its physics implications

The trigger systems of the LHC detectors play a crucial role in determining the physics capabilities of the experiments. The CMS experiment implements a sophisticated two-level triggering system composed of the Level-1(L1), instrumented by custom-design hardware boards, and the High Level Trigger(HLT), a streamlined version of the offline reconstruction software running on a computer farm. For Phase2 of the LHC, the increase in the instantaneous luminosity and pile-up will raise the event rate to a level which is extremely challenging for the trigger algorithms. New approaches and optimizations have been studied to keep the trigger rate manageable while maintaining thresholds low enough to cover the needs of physics analyses. We will show the optimizations and improvements that are being done for Phase2 electron and photon triggers to allow pileup mitigation exploiting the highly granular calorimeter in endcap(HGCAL). Moreover, the addition of the tracker information at L1 and the enhanced computing resources at HLT will also help to maintain the trigger efficiency and thresholds in Phase2 at a similar level as Run2.

Speaker: Ms Swagata Mukherjee (Rheinisch Westfaelische Tech. Hoch. (DE))

Pheno2021_SM.pdf

17:15 Study of energy deposition patterns in hadron calorimeter for prompt and displaced jets using convolutional neural network

Sophisticated machine learning techniques have promising potential in search for physics beyond Standard Model (BSM) in Large Hadron Collider (LHC). Convolutional neural networks (CNN) can provide powerful tools for differentiating between patterns of calorimeter energy deposits by prompt particles of Standard Model and long-lived particles predicted in various models beyond the Standard Model. We demonstrate the usefulness of CNN by using a couple of physics examples from well motivated BSM scenarios predicting long-lived particles giving rise to displaced jets. Our work suggests that modern machine-learning techniques have the potential to discriminate between energy deposition patterns of prompt and long-lived particles, and thus, they can be useful tools in such searches.

Speaker: Ms Rhitaja Sengupta (Indian Institute of Science, Bengaluru)

rhitaja_pheno21.pdf

17:30 A $W^\pm$ polarization analyzer from Deep Neural Networks

In this paper we train a Convolutional Neural Network to classify longitudinally and transversely polarized hadronic $W^\pm$ using the images of boosted $W^{\pm}$ jets as input. The images capture angular and energy information from the jet constituents that is faithful to properties of the original quark/anti-quark $W^{\pm}$ decay products without the need for invasive substructure cuts. We find that the difference between the polarizations is too subtle for the network to be used as an event-by-event tagger. However, given an ensemble of $W^{\pm}$ events with unknown polarization, the average network output from that ensemble can be used to extract the longitudinal fraction $f_L$. We test the network on Standard Model $pp \to W^{\pm}Z$ events and on $pp \to W^{\pm}Z$ in the presence of dimension-6 operators that perturb the polarization composition.

Speaker: Taegyun Kim (University of Notre Dame)

TaegyunKim_Wpol_Pheno.pdf

17:45 Effective collider data analysis with ADL and CutLang

Collider data analysis, which usually requires complicated software frameworks, has a very steep learning curve. Therefore, a sizable barrier exists between data and the physicist wishing to work on different analysis ideas. Recently, a new approach has been under development to address this issue and provide a practical way to collider data analysis. This approach features the so-called "Analysis Description Language" (ADL), a domain specific, declarative language capable of describing the contents of an LHC analysis in a standard and unambiguous way, independent of any computing frameworks. In ADL, analyses are written in human-readable text files, separating object, variable and event selection definitions in blocks. The ADL syntax includes mathematical and logical operations, comparison and optimisation operators, reducers, four-vector algebra and commonly used functions. ADL can be rendered executable on event data with any infrastructure capable of understanding its syntax. The first such complete infrastructure is the CutLang runtime interpreter, which can run ADL analyses on data witout any need for programming in a general purpose language. ADL and CutLang are designed for use in both experimental and phenomenological data analyses, and are also being integrated for use with the LHC Open Data. A number of LHC analyses have already been implemeted with ADL to form an analysis database for interpretation of experimental results or other phenomenology studies. ADL/CutLang also provde a practical setup to effectively perform collider sensitivity studies. This talk will introduce ADL and CutLang and their growing applications in different areas of collider analysis.

Speaker: Sezen Sekmen (Kyungpook National University (KR))

SekmenADLPheno2105.pdf

18:00 Constraining new physics with SModelS v2.0: long-lived particles

SModelS is an automatic, public python tool providing a fast reinterpretation of simplified model results from the LHC within any model of new physics respecting a Z_2 symmetry. We present the recently released v2.0 that includes a major revision of the decomposition algorithm. It introduces the particles’ decay widths and their quantum numbers as additional parameters of the simplified model topologies. This enables to incorporate a wide range of exotic signatures, such as searches for disappearing and kinked tracks, displaced jets and leptons as well as delayed jets and photons. In total, our database contains simplified models results of over 100 CMS and ATLAS publications including prompt and long-lived particle searches. We demonstrate the impact on various new physics scenarios motivated by dark matter.

Speaker: Dr Jan Heisig (Université catholique de Louvain (UCL))

Heisig_SModelS_Pheno_May2021.pdf

18:15 Tuning Pythia for Forward Physics at the LHC

Lately, interest has grown in forward, high $\eta$ physics with experiments like FASER and FORMOSA at the LHC. However, particle physics event generators like Pythia have primarily been calibrated to make predictions in the central, low $\eta$ regions. As such, predictions in the forward region are in tension with current forward physics data. It is imperative to obtain accurate particle productions, to fully utilize these novel forward experiments. In this talk I will discuss the progress we have made to tune Pythia for forward experiments. This tune will provide a practical tool to determine particle production rates in the forward region, and can be used to study neutrino interactions, BSM physics, and cosmic rays.

Speaker: Max Fieg

Pheno.pdf

Pheno_v2.pdf

18:30 Artificial Event Variables for Collider Analyses

In this talk, we will introduce a technique to train neural networks into being good event variables, which are useful to an analysis over a range of values for the unknown parameters of a model.

We will use our technique to learn event variables for several common event topologies studied in colliders. We will demonstrate that the networks trained using our technique can mimic powerful, previously known event variables like invariant mass, transverse mass, and MT2.

We will describe how the machine learned event variables can go beyond the hand-derived event variables in terms of sensitivity, while retaining several attractive properties of event variables, including the robustness they offer against unknown modeling errors.

Speaker: Prasanth Shyamsundar (Fermi National Accelerator Laboratory)

Presentation.pdf

Tuesday 25 May

08:45 → 10:30 Plenary: III

https://pitt.zoom.us/j/93951025550

Conveners: Doreen Wackeroth (SUNY Buffalo), Doreen Wackeroth (SUNY Buffalo)

zoom

08:45 Recent LHC Results

Speaker: Tulika Bose (University of Wisconsin Madison (US))

PHENO-LHC-Results-Bose.pdf

09:20 LHC phenomenology

Speaker: Prof. Veronica Sanz Gonzalez (University of Sussex (GB))

Pheno21.pdf

09:55 Future Perspectives at HL-LHC

Speaker: Laura Jeanty (University of Oregon (US))

jeanty_pheno2021_HL_LHC.pdf

10:30 → 11:00 Coffee break

11:00 → 12:45 Plenary: IV

https://pitt.zoom.us/j/93951025550

Convener: Christophe Grojean (DESY (Hamburg) and Humboldt University (Berlin))

zoom

11:00 Muon g-2 and muon physics on Fermilab campus

Speakers: James Mott (Fermi National Accelerator Laboratory), James Mott (Boston University)

2021_05_25 - PHENO2021 - Mott g-2.pptx

11:35 Beauty physics from Belle II

Speaker: Christoph Schwanda (Austrian Academy of Sciences (AT))

pheno2021_schwanda_25may2021.pdf

12:10 Anomalies and their implications

Speakers: Bhupal Dev (Washington University in St. Louis), P. S. Bhupal Dev (Washington U.)

dev_pheno21.pdf

dev_pheno21.pptx

12:45 → 14:00 Lunch

14:00 → 16:00 BSM III

Convener: Richard Ruiz

Zoom

14:00 Searches for new phenomena in leptonic or hadronic final states using the ATLAS detector

Many theories beyond the Standard Model predict new phenomena, such as Z’, W’ bosons, vector-like quarks, or heavy neutrinos. Searches for new physics in different final state signatures, produced either resonantly or non-resonantly, including a general search using multilepton final states are performed using the ATLAS experiment at the LHC. Lepton flavor violation (LVF) is a striking signature of potential beyond the Standard Model physics. The search for LFV with the ATLAS detector is reported in searches focusing on the decay of the Z boson into different flavour leptons (e/mu/tau). The most recent 13 TeV pp results will be reported.

Speaker: Avik Roy (University of Texas at Austin (US))

Avik-Pheno2021.pdf

14:15 Searches for vector-like quarks at CMS

We present results of searches for vector-like quarks using proton-proton collision data collected with the CMS detector at the CERN LHC at a center-of-mass energy of 13 TeV. Single and pair production of vector-like quarks are studied, with decays into a variety of final states, containing top and bottom quarks, electroweak gauge and Higgs bosons. The presented searches make use of a wide variety of reconstructed objects, allowing to explore diverse signatures from multi-leptonic to fully hadronic. We set exclusion limits on the vector-like quark masses and cross sections, and for combinations of the vector-like quark branching ratios.

Speaker: Francesco Fabozzi (Universita e sezione INFN di Napoli (IT))

fabozzi_VLQ_CMS.pdf

14:30 The anomalous $Zb\bar{b}$ couplings: From LEP to LHC

The bottom quark forward-backward asymmetry ($A_{FB}^b$) data at LEP exhibits a long-standing discrepancy with the standard model prediction.
We propose a novel method to probe the $Zb\bar{b}$ interactions through $gg\to Zh$ production at the LHC, which is sensitive to the axial-vector component of the $Zb\bar{b}$ couplings. We demonstrate that the $Zh$ data collected at the 13 TeV LHC can already resolve the apparent degeneracy of the anomalous $Zb\bar{b}$ couplings implied by the LEP precision electroweak measurements, with a strong dependence on the observed distribution of the $Z$ boson transverse momentum.
We also show the potential of the HL-LHC to either verify or exclude
the anomalous $Zb\bar{b}$ couplings observed at LEP through measuring the $Zh$ production rate
at the HL-LHC, and this conclusion is not sensitive to possible new physics contribution induced by top quark or Higgs boson anomalous couplings in the loop.

Speaker: Dr Bin Yan (Los Alamos National Laboratory)

zbb.pdf

14:45 Single Vector-Like quark production via chromo-magnetic moment at the LHC

In many models that address the naturalness problem, top-quark partners are often postulated in order to cure the issue related to the quadratic corrections of the mass of the Higgs boson. In this work, we study alternative modes for the production of top- and bottom-quark partners ($T$ and $B$), $pp\rightarrow B$ and $pp\rightarrow T\bar{t}$, via a chromo-magnetic moment coupling. We adopt the simplest composite Higgs effective theory for the top-quark sector incorporating partial compositeness, and investigate the sensitivity of the 14 TeV LHC.

Speaker: Xing Wang (UC San Diego)

slides_Xing_Wang.pdf

15:00 Scalar Leptoquark Pair Production at Hadron Colliders

I will present precision predictions for scalar leptoquark pair production at hadron colliders. Apart from QCD contributions, included are the lepton t-channel exchange diagrams relevant in the light of the recent B-flavor anomalies. All contributions are evaluated at next-to-leading order in QCD and improved by resummation corrections, in the threshold regime, from soft-gluon radiation at next-to-next-to-leading-logarithmic accuracy. All corrections are found equally relevant. Furthermore, the impact of different sets of parton distribution functions will be discussed. These predictions consist of the most precise leptoquark cross section calculations available to date and are necessary for the best exploitation of leptoquark LHC searches.

Speaker: Christoph Borschensky (University of Tübingen)

Borschensky_Scalar_LQs_Pheno21.pdf

15:15 Searches for new physics in events with leptons in the final state in CMS

Many new physics models, e.g., compositeness, extra dimensions, extended Higgs sectors, supersymmetric theories, and dark sector extensions, are expected to manifest themselves in the final states with leptons and photons. This talk presents searches in CMS for new phenomena in the final states that include leptons and photons, focusing on the recent results obtained using the full Run-II data-set collected at the LHC.

Speaker: Jie Xiao (Peking University (CN))

pheno2021_bsm_leptons.pdf

15:30 Searches for leptoquarks with the ATLAS detector

Leptoquarks (LQ) are predicted by many new physics theories to describe the similarities between the lepton and quark sectors of the Standard Model and offer an attractive potential explanation for the lepton flavour anomalies observed at LHCb and flavour factories. The ATLAS experiment has a broad program of direct searches for leptoquarks, coupling to the first-, second- or third-generation particles. This talk will present the most recent 13 TeV results on t he searches for leptoquarks and contact interactions with the ATLAS detector, covering flavour-diagonal and cross-generational final states.

Speaker: Andre Sopczak (Czech Technical University in Prague (CZ))

Sopczak_Pheno21_final.pdf

15:45 ≥4mu signal from a vector-like lepton decaying to a muon-philic Z′ boson at the LHC

We propose a novel possibility to detect a very distinctive signal with more than four muons originating from pair-produced vector-like leptons decaying to a muon-philic Z′ boson. These new particles are good candidates to explain the anomalies in the muon anomalous magnetic moment and the b→sℓℓ processes. The doublet (singlet) vector-like leptons lighter than 1.3 (1.0) TeV are excluded by the latest data at the LHC if BR(E→Z′μ)=1. We also show that the excess in the signal region with more than five leptons can be explained by this scenario if the vector-like lepton is a weak singlet, with mass about 400 GeV and BR(E→Z′μ)=0.25. The future prospects at the HL-LHC are discussed.

Speaker: Dr Junichiro Kawamura (Ohio State University, Keio University)

JKawamura_pheno2021.pdf

14:00 → 16:00 BSM VIII

Convener: Jure Zupan (University of Cincinnati)

zoom

14:00 Light Scalar and Lepton Anomalous Magnetic Moments

Recent precise determination of the electron anomalous magnetic moment (AMM) adds to the longstanding tension of the muon AMM and together strongly point towards physics beyond the Standard Model (BSM). Here we present a solution to both anomalies via a light scalar that emerges from a second Higgs doublet and resides in the $\mathcal{O}(10)$-MeV to $\mathcal{O}(1)$-GeV mass range. A scalar of this type is subject to a number of various experimental constraints, however, as we show, it can remain sufficiently light by evading all experimental bounds and has the great potential to be discovered in the near-future low-energy experiments. In addition to the light scalar, our theory predicts the existence of a nearly degenerate charged scalar and a pseudoscalar, which have masses of the order of the electroweak scale. This scenario can be tested at the LHC by looking at the novel process $pp \to H^\pm H^\pm jj \to l^\pm l^\pm j j + {E\!\!\!\!/}_{T}$ via same-sign pair production of charged Higgs bosons.

Speaker: Vishnu Padmanabhan Kovilakam (Oklahoma State University)

leptonAMM_lightscalar_PHENO.pdf

14:15 Electroweak Symmetry Non-restoration in UV-complete Models with New Fermions

In certain extensions of the Standard Model(SM), the interactions between the new scalars and the SM Higgs can cause the electroweak(EW) symmetry to remain broken at temperatures well above the electroweak scale. Fermionic-induced EW symmetry non-restoration (EWSNR) effect has also been studied in the context of effective field theories, where EWSNR is linked to some non-renormalizable interactions; thus, fermionic-induced EWSNR only occurs below specific cutoff temperature. In this talk, I will introduce some UV-complete models with new fermions that have unstored EW symmetry at high temperatures. In these models, fermionic-induced EWSNR is not limited by a cutoff temperature because some of the heavy fermions are always decoupled from thermal equilibrium at high temperatures as a consequence of their mass mechanisms. Then, I will identify the parameter space that satisfies the theoretical (stability of effective potential, perturbative unitarity bound, thermal equilibrium conditions) and experimental constraints. Within this parameter space, I will examine the novel thermal histories of these models and their phenomenological implications.

Speaker: Yu Hang Ng (University of Nebraska-Lincoln)

EWSNR_pheno.pdf

14:30 Freeze-in Leptogenesis via Dark Matter Oscillations

Models of freeze-in dark matter that incorporate two or more dark matter mass eigenstates, typically below $\sim$100 keV, can simultaneously account for the observed baryon asymmetry, through the oscillations of the out-of-equilibrium dark matter particles. We consider the case in which the dark matter is produced by early-universe decays of electroweak-charged scalars, the lightest of which is typically in the few hundred GeV to few TeV range to realize the observed dark matter and baryon densities. Using a network of quantum kinetic equations that describe dark matter production, annihilation, and oscillations, along with washout and spectator processes, we find that the minimal model, with two dark matter mass eigenstates and a single scalar, is tightly constrained. Including Yukawa couplings of the scalar beyond its interaction with the dark matter or adding one or more additional scalars significantly expands the viable parameter space, much of which has the lightest scalar being long-lived at colliders. We discuss the model’s discovery potential at the Large Hadron Collider along with other possible experimental probes.

Speaker: Justin Berman (Williams College)

Berman_Talk_052521.pdf

14:45 Crunching dilaton, hidden naturalness

We introduce a new approach to the Higgs naturalness problem, where the value of the Higgs mass is tied to cosmic stability and the possibility of a large observable Universe. The Higgs mixes with the dilaton of a CFT sector whose true ground state has a large negative vacuum energy. If the Higgs VEV is non-zero and below ~TeV, the CFT also admits a second metastable vacuum, where the expansion history of the Universe is conventional. As a result, only Hubble patches with unnaturally small values of the Higgs mass support inflation and post-inflationary expansion, while all other patches rapidly crunch. The elementary Higgs VEV driving the dilaton potential is the essence of our new solution to the hierarchy problem. The main experimental prediction is a light dilaton field in the 0.1-10 GeV range that mixes with the Higgs. Part of the viable parameter space has already been probed by measurements of rare B-meson decays, and the rest will be fully explored by future colliders and experiments searching for light, weakly-coupled particles.

Speaker: Ameen Ismail (Cornell University)

main.pdf

15:00 Collider and GW complementarity in the 2HDM

We study electroweak phase transition and resultant GWs of a CP conserving 2HDM with a softly broken $Z_2$ symmetry. We analysed the parameter space of both type I and type II 2hdm without relying on any decoupling limit. We observe $M_{H^\pm} \approx M_H$ or $M_{H^\pm} \approx M_A$ favours SFOEWPT in 2HDM. In addition to di-Higgs production, scalar to fermion decay channel is also important to probe phase transition behaviour in 2HDM. We also comment about the shape of potential leading to SFOEWPT in 2hdm.

Speaker: AJAY Kaladharan (Oklahoma State University)

R2HDM_GW (2).pdf

15:15 Vacuum stability in dynamical seesaw model

The Standard Model (SM) vacuum is unstable for the measured values of the
top Yukawa coupling and Higgs mass. We study the issue of vacuum stability
when neutrino masses are generated through spontaneous low-scale lepton number
violation. In the simplest dynamical inverse seesaw, the SM Higgs has two siblings: a massive CP -even scalar plus a massless Nambu-Goldstone boson, called majoron. For TeV scale breaking of lepton number, Higgs bosons can have a sizeable decay into the invisible majorons. We examine the interplay and complementarity of vacuum stability and perturbativity restrictions, with collider constraints on visible and invisible Higgs boson decay channels. This simple framework may help guiding further studies, for example, at the proposed FCC facility.

Speaker: Dr Sanjoy Mandal (Instituto de Física Corpuscular)

VacuumStabilitySanjoyPheno.pdf

15:30 Interference Effect in LNV and LNC Meson Decays for Left Right Symmetric Model

We study the effect of interference on the lepton number violating (LNV) and lepton number conserving (LNC) three-body meson decays $M^+_1 → l^+_i l^±_j π^∓$, that arise in a TeV scale Left Right Symmetric model (LRSM) with degenerate or nearly degenerate right handed (RH) neutrinos. LRSM contains three RH neutrinos and a RH gauge boson. The RH neutrinos with masses in the range of $M_N$$∼$(MeV - few GeV) can give resonant enhancement in the semi-leptonic LNV and LNC meson decays. In the case, where only one RH neutrino contributes to these decays, the predicted new physics branching ratio of semi-leptonic LNV and LNC meson decays $M^+_1 → l^+_i l^+_j π^−$ and $M^+_1 → l^+_i l^−_j π^+$ are equal. We find that with at least two RH neutrinos contributing to the process, the LNV and LNC decay rates can differ. Depending on the neutrino mixing angles and CP violating phases, the branching ratios of LNV and LNC decay channels mediated by the heavy neutrinos can be either enhanced or suppressed, and the ratio of these two rates can differ from unity.

Speaker: Mr Siddharth Prasad Maharathy (Institute of Physics)

Presentation_pheno.pdf

15:45 Multi-charged TeV scale scalars and fermions in the framework of a radiative seesaw model

Explaining the tiny neutrino masses and non-zero mixings have been one of the key motivations for going beyond the framework of the Standard Model (SM). We discuss a collider testable model for generating neutrino masses and mixings via radiative seesaw mechanism. That the model does not require any additional symmetry to forbid tree-level seesaws makes its collider phenomenology interesting. The model includes multi-charged fermions/scalars at the TeV scale to realize the Weinberg operator at 1-loop level. After deriving the constraints on the model parameters resulting from the neutrino oscillation data as well as from the upper bound on the absolute neutrino mass scale, we discuss the production, decay and resulting collider signatures of these TeV scale fermions/scalars at the Large Hadron Collider (LHC). We consider both Drell-Yan and photo-production. The bounds from the neutrino data indicate the possible presence of a long-lived multi-charged particle (MCP) in this model. We obtain bounds on these long-lived MCP masses from the ATLAS search for abnormally large ionization signature. When the TeV scale fermions/scalars undergo prompt decay, we focus on the 4-lepton final states and obtain bounds from different ATLAS 4-lepton searches.

Speaker: Mr Avnish . (Institute of Physics)

Phneo_2021.pdf

14:00 → 16:00 Cosmology III

https://pitt.zoom.us/j/91379044495

Zoom

14:00 Constraints on Axions from Cosmic Distance Measurements

Axion couplings to photons could induce photon-axion conversion in the presence of magnetic fields in the Universe. The conversion could impact various cosmic distance measurements such as luminosity distances to type Ia supernovae and angular distances to galaxy clusters in different ways. We consider different combinations of the most updated distance measurements to constrain the axion-photon coupling. Ignoring the conversion in intracluster medium (ICM), we find the upper bounds on axion-photon couplings to be around $5 \times 10^{−12} ~({\rm nG}/B)~ {\rm GeV}^{−1}$ for axion mass below $5 \times 10^{−13}~ {\rm eV}$, where B is the strength of the magnetic field in the intergalactic medium (IGM). When including the conversion in ICM, the upper bound gets stronger and could be as strong as $5 \times 10^{−13} ~ \mathrm{GeV}^{−1}$ for $m_a < 5 \times 10^{−12} ~ \mathrm{eV}$. While this stronger bound depends on the ICM modeling moderately, it is independent of the IGM parameters.

Speaker: Manuel Buen-Abad (Brown University)

Pheno21 -- Cosmo Axions -- M. Buen-Abad.pdf

14:15 Cosmological Tension of Ultralight Axion Dark Matter and its Solutions

A number of proposed and ongoing experiments search for axion dark matter with a mass nearing the limit set by small scale structure. I will discuss the late universe cosmology of these models and show that requiring the axion to have a matter-power spectrum that matches that of cold dark matter constrains the magnitude of the axion couplings to the visible sector. I will also survey mechanisms that can alleviate the bounds, namely, the introduction of large charges, various forms of kinetic mixing, a clockwork structure, and imposing a discrete symmetry. We provide an explicit model for each case and explore their phenomenology and viability to produce detectable ultralight axion dark matter.

Speaker: Jacob Leedom (University of California, Berkeley)

JML_Pheno2021v2.pdf

14:30 CMB birefringence due to ultra-light axion strings

Ultralight axions (ULA), whose masses can lie in a wide range of values and can be even smaller than $10^{-28}$ eV, are generically predicted in UV theories such as string theory. In the cosmological context, the early Universe may have gotten filled with a network of ultralight axion (ULA) cosmic strings which, depending upon the mass of the axion, can survive till very late times. If the ULA also couples to electromagnetism, and the network survives post recombination, then the interaction between the strings and the CMB photons induces a rotation of the polarization axis of the CMB photons (otherwise known as the birefringence effect). This effect is independent of the string tension, and only depends on the coupling between the ULA and the photon (which in turn is sensitive to UV physics). In this talk I will present some results for this birefringence effect on CMB, due to three different models of string network. Interestingly, this is within the reach of some current and future CMB experiments.

Speaker: Mudit Jain (Rice University)

14:45 Gravity waves from nonlinear dynamics of axion-likie particles

Axion-like particles (ALPs) play an important role for inflationary model building, as well as are well motivated dark matter candidates. The out-of-equilibrium initial conditions, combined with their possibly nontrivial potentials, allow for a rich nonlinear dynamics of such fields in the early universe.

We consider the coherent oscillations of an ALP field in a wiggly potential and investigate the scenario when the fluctuations on top of the homogeneous field are amplified via parametric instabilities, leading to the complete fragmentation of the field. If the potential contains several local minima, separated by barriers, transitions between such minima can be induced via bubble nucleation. We investigate such transitions, taking into account the dynamical, nonthermal nature of the process and the impact of fragmentation. The above mentioned processes are accompanied by the production of a stochastic gravitational wave background, possibly within reach of future detectors.

Speaker: Dr Aleksandr Chatrchyan (Deutsches Elektronen-Synchrotron DESY)

15:00 White Dwarfs as Axion Probes

Axions, if they exist, can be produced efficiently in white dwarfs, free-stream out of the star due to their weak interactions with matter, and then be converted to a photon in the stellar magnetosphere. X-ray telescope observations of these stars can provide strong constraints on the coupling to electromagnetism and matter. I discuss the results of the first dedicated observation of a magnetic white dwarf in hard X-rays, and what it tells us about axions.

Speaker: Christopher Dessert (University of Michigan)

Pheno_2021.key

15:15 Flavor-specific Neutrino self interaction in Cosmology

Neutrino self-interaction has been proposed as a solution to the Hubble tension, a discrepancy between the measured values of the Hubble constant from CMB and low-redshift data. However, flavor-universal neutrino self-interaction is highly constrained by BBN and laboratory experiments such as K-meson and tau decay, double-neutrino beta decay etc. In this talk, I will discuss the cosmology of flavor specific neutrino self-interaction where only one or two neutrino flavor states are self-interacting. Such flavor-specific interactions are less constrained by the laboratory experiments. I will show that CMB and other cosmological dataset favours strong flavor specific neutrino self-interaction. Finally, I will talk about the feasibility of addressing the Hubble tension in this framework.

Speaker: Mr Subhajit Ghosh (University of Notre Dame)

SG-PHENO-21.pdf

15:30 Resonant neutrino self-interactions in astrophysical spectra

If neutrino self-interactions arise from beyond-Standard Model physics, there will be scattering between astrophysical and cosmic background neutrinos. As a result, resonance features can appear in astrophysical neutrino spectra. While the flavor-diagonal case has been studied before numerically, we present an analytic result for arbitrary self-coupling matrix, allowing for possibilities such as self-interactions only between tau neutrinos. We then examine effects on the diffuse supernova neutrino background and high-energy astrophysical neutrinos.

Speaker: Jeffrey Hyde (Bowdoin College)

Hyde_Pheno2021.pdf

Hyde_Pheno2021.pptx

14:00 → 16:00 DM III

Convener: Flip Tanedo (UC Riverside)

Zoom link DM III

14:00 Freeze-in Dark Matter from a Minimal B-L Model and Possible Grand Unification

We show that a minimal local B−L symmetry extension of the standard model can provide a unified description of both neutrino mass and dark matter. In our model, B−L breaking is responsible for neutrino masses via the seesaw mechanism, whereas the real part of the B−L breaking Higgs field (called σ here) plays the role of a freeze-in dark matter candidate for a wide parameter range. Since the σ-particle is unstable, for it to qualify as dark matter, its lifetime must be longer than 1025 seconds implying that the B−L gauge coupling must be very small. This in turn implies that the dark matter relic density must arise from the freeze-in mechanism. The dark matter lifetime bound combined with dark matter relic density gives a lower bound on the B−L gauge boson mass in terms of the dark matter mass. We point out parameter domains where the dark matter mass can be both in the keV to MeV range as well as in the PeV range. We discuss ways to test some parameter ranges of this scenario in collider experiments. Finally, we show that if instead of B−L, we consider the extra U(1) generator to be −4I3R+3(B−L), the basic phenomenology remains unaltered and for certain gauge coupling ranges, the model can be embedded into a five dimensional SO(10) grand unified theory.

Speaker: Nobuchika Okada (University of Alabama)

NobuOkada_Pheno_2021.pdf

14:15 Testing freeze-in with $Z'$ bosons

If dark matter particles interact too feebly with ordinary matter, they have never been able to thermalize in the early universe. Such Feebly Interacting Massive Particles (FIMPs) would be therefore produced via the freeze-in mechanism. Testing FIMPs is a challenging task, given the smallness of their couplings. In this talk, after giving a brief overview on the phenomenology of FIMPs, I will discuss our recent proposal of a $ Z'$ portal where the freeze-in can be currently tested by many experiments. In our model, $ Z'$ bosons with mass in the MeV-PeV range have both vector and axial couplings to ordinary and dark fermions. We constraint our parameter space with bounds from direct detection, atomic parity violation, leptonic anomalous magnetic moments, neutrino-electron scattering, collider, and beam dump experiments.

Speaker: Maíra Dutra (Carleton University)

MairaDutra_PHENO21.pdf

14:30 Spin-2 mediated Dark Matter in Warped Extra-Dimensions

We present a study of spin-2 mediated scalar dark matter. As a blueprint, we work in a warped extra-dimensional model such that the mediator(s) are the massive spin-2 Kaluza-Klein (KK) modes of the 5D graviton. On top of Standard Model particles, we focus on dark matter annihilations into KK-gravitons. Due to the longitudinal modes of the massive gravitons, any truncation of the KK-tower leads to a tremendous growth of the amplitude at large center of mass energies $\sqrt{s}$, which heavily impacts any phenomenological analysis. For the first time, we include the full KK-tower in this dark matter production process and find that this growth is unphysical and cancels once the full field content of the extra-dimensional theory is taken into account. Interestingly, this implies that it is not possible to approximate the results obtained in the full theory with a reduced set of effective interactions once $\sqrt{s}$ is greater than the lightest massive graviton. This casts some doubt on the universal applicability of previous studies with spin-2 mediators within an EFT framework and prompts us to revisit the phenomenological allowed parameter space.

Speaker: Arturo de Giorgi (Max Planck Institute for Physics)

Spin2_Mediated_DM.pdf

14:45 Exploring the Co-SIMP Dark Sector

A particularly salient aspect of particle dark matter models is the connection between thermal interactions and cosmological abundance. Extending from the famous WIMP paradigm is a rich sector of dark sector models with different number changing mechanisms, all of which realize a relic abundance via interactions with the Standard Model or itself. In this talk I will introduce one of these scenarios: Co-SIMP dark matter, whose key interactions involve both cannibalistic interactions and couplings to the Standard Model. I will discuss the phenomenology and UV completions of this scenario, as well as constraints and prospects for detection.

Speaker: Aditya Parikh (Harvard University)

CoSIMP_Pheno_AdityaParikh.pdf

15:00 Prospect of a light pseudoscalar dark matter

The idea of with EW-$\nu_R$ model with additional GeV scale mirror fermions with large displaced vertices and extended Scalar sector is very appealing from the Collider perspective. The presence of a complex singlet scalar in this model helps to solve the strong-CP problem, satisfying the constraint coming from the present absence of neutron electric dipole moment, and without need of an axion.
Based on this model, in this work, we study the detailed scalar mass spectrum, having $\sim 125$ GeV Higgs-like scalar, which is allowed by the signal strength and lepton flavor violating constraints data. Besides explaining the $\sim 125$ GeV Higgs-like scalar, this scenario can also accommodate a non-thermal scalar dark matter candidate that can satisfy the relic density data.
The imaginary part of the complex singlet scalar in this model serves as a viable non-thermal feebly interacting massive particle (FIMP) dark matter candidate.
We identify the region of the parameter space for the freeze-in scenario, which is consistent with all the bounds from relic density and direct-indirect searches and discuss the possible future implications of this scenario.

Speaker: Shreyashi Chakdar

Chakdar_Pheno2021.pdf

15:15 Phenomenology of Dark matter in two higgs doublet models with complex scalar singlet

Extensions of the two higgs doublet models with a singlet scalar can easily accommodate all current experimental constraints and are highly motivated candidates for Beyond Standard Model Physics. It can successfully provide a dark matter candidate, explain baryogenesis and provide gravitational wave signals. In this work, we focus on the dark matter phenomenology of the two higgs doublet model extended with a complex scalar singlet which serves as the dark matter candidate. We study the variations of the dark matter observables, ie, relic density and direct detection cross-section, with respect to the model parameters. We obtain a few benchmark points in the light and heavy dark matter mass region. We are also currently studying possible signatures of this model at current and future colliders and the possibility to distinguish this model from other new physics scenarios.

Speaker: Juhi Dutta (University of Hamburg)

JuhiDutta_Pheno21.pdf

15:30 A model of electroweakly interacting non-abelian vector dark matter

In this talk, we propose a new electroweakly interacting spin-1 dark matter (DM) model. We consider the non-Abelian extension of electroweak symmetry. Namely, we extend the SU(2)$_L$ group in the Standard Model (SM) into the direct products of three SU(2) groups. We also impose the exchange symmetry between two of these SU(2) groups to realize the spin-1 stable spectrum. In this setup, the DM pair efficiently annihilate into SM particles through the electroweak interaction. Therefore, we can obtain the DM energy density correctly via the freeze-out mechanism. We also find not only electroweak processes but also Higgs exchange processes give the relevant contribution to determine the DM energy density. We conclude a next-generation DM searches will be an excellent probe of this spin-1 DM.

Speaker: Ms Motoko Fujiwara (Nagoya University)

Motoko_Fujiwara.pdf

15:45 Continuum-Mediated Self-Interacting Dark Matter

Dark matter self-interactions have been proposed as a solution to various astrophysical small-scale structure anomalies. We explore the scenario in which dark matter self-interacts through a continuum of low-mass states. This happens if dark matter couples to a strongly-coupled nearly-conformal hidden sector. This type of theory is holographically described by brane-localized dark matter interacting with bulk fields in a slice of 5D anti-de Sitter space. The long-range potential in this scenario depends on a non-integer power of the spatial separation. We find that continuum mediators introduce novel power-law scalings for the scattering cross section, opening new possibilities for dark matter self-interaction phenomenology.

Speaker: Ian Chaffey (University of California, Riverside)

Continuum-Mediated Self-Interacting Dark Matter

14:00 → 16:00 Flavor III

https://pitt.zoom.us/j/97533519613

Convener: Dr Da Liu (ITP, CAS/EPFL)

zoom

14:00 The SM expectation for muon g-2

Speaker: Hartmut Wittig (Johannes Gutenberg Universitaet Mainz (DE))

Wittig_gm2_Pheno2021.key

Wittig_gm2_Pheno2021.pdf

14:30 $R_{D^{(*)}}$, $R_{K^{(*)}}$ and muon g-2 anomalies in RPV supersymmetry and the discovery prospect at LHC

In R-parity violating supersymmetric scenario, assuming the third-generation superpartners to be the lightest (calling the scenario RPV3), we show that there are some benchmark scenarios in which $R_{D^{(*)}}$ and / or $R_{K^{(*)}}$ and / or $(g-2)_{\mu}$ anomalies can be addressed and also can be detected at LHC 14 TeV or future 27 TeV hadron collider. We consider $\overline{t}\tau\overline{\tau}$ or $\overline{t}\mu\overline{\mu}$ for different cases as our final states to be detected at colliders because there is no simple Standard Model (SM) process can have this kind of final state and the background cross-section is thus very small.

Speaker: Fang Xu

Pheno2021-FangXu.pdf

14:45 Searches for lepton flavour and lepton number violation in K+ decays

The NA62 experiment at CERN collected a large sample of charged kaon decays into final states with multiple charged particles in 2016-2018. This sample provides sensitivities to rare decays with branching ratios as low as 10-11. Searches for lepton flavour and lepton number violating decays of the charged kaon into final states containing a lepton pair based on this data set are presented.

Speaker: Joel Christopher Swallow (University of Birmingham (GB))

PHENO21_JSwallow_NA62_LNVLFV_vF.pdf

15:00 Flavourful Feebly-Interacting Particles for flavour and g-2 anomalies

Flavourful Feebly-Interacting Particles (FIPs) in the MeV to GeV range have a strong impact on precision frontier observables ranging from rare meson decays to the lepton anomalous magnetic moments. We use an effective field theory approach “SM+X” along with the HEPfit package to study the effect of FIPs on B to K observables. We present an updated study of the available parameter space and constraints, focusing on FIP scenarios allowing for a simultaneous fit of both the $R_{K^{(*)}}$ and the $(g-2)_{\mu}$ anomalies. We further present an explicit UV realization.

Speaker: Luc Jean Marie Darmé (INFN - National Institute for Nuclear Physics)

PHENO_DARME.pdf

15:15 New Contributions to Flavor Observables from Left-Right Symmetric Models with Universal Seesaw

A Left-Right Symmetric Model which utilizes vector-like fermions to generate quark and lepton masses via universal see-saw mechanism is studied. In this talk, I will present the results of our analysis on the new contributions to flavor observables from this model. Further, I will discuss the possibilities of explaining the neutral current B-anomalies as well as the Cabibbo anomaly in this model.

Speaker: Ritu Dcruz (Oklahoma State University)

Left-RightSymmetric Models with Universal Seesaw.pdf

15:30 Explaining $g_{\mu}-2$ and $R_{K^{(*)}}$ using the light mediators of $U(1)_{T3R}$

Scenarios in which right-handed light Standard Model fermions couple to a new gauge group, $U(1)_{T3R}$ can naturally generate a sub-GeV dark matter candidate. But such models necessarily have large couplings to the Standard Model, generally yielding tight experimental constraints. We show that the contributions to $g_\mu-2$ from the dark photon and dark Higgs largely cancel out in the narrow window where all the experimental constraints are satisfied, leaving a net correction which is consistent with recent measurements from Fermilab.These models inherently violate lepton universality, and UV completions of these models can include quark flavor violation which can explain $R_{K^{(\ast)}}$ anomalies as observed at the LHCb experiment after satisfying the $B_s\rightarrow\mu\mu$ constraint in the allowed parameter space of the model. This scenario can be probed by FASER, SeaQuest, SHiP, LHCb, Belle etc.

Speaker: Sumit Ghosh (Texas A&M University)

PHENO2021_SG.pdf

15:45 Testing Lepton Flavor Universality at the Z Pole

$b\to s\tau\tau$ and $b\to c\tau \nu$ measurements are highly motivated for addressing lepton-flavor-universality-violating (LFUV) puzzles, such as $R_{D^{(*)}}$, $R_{J/\psi}$ and $R_{K^{(\ast)}}$ anomalies, raised by the data of LHCb, BELLE and BarBar. The planned operation of future $e^-e^+$ colliders as a $Z$ factory provides a great opportunity to conduct such measurements, because of its relatively high production rates and reconstruction efficiency for $B$ mesons at $Z$ pole. In this project we will pursue a systematic sensitivity study on these measurements at future $Z$ factories. The implications of the outcomes for LFUV new physics will be also explored.

Speaker: LINGFENG LI (HKUST)

Slides_veryshort.pdf

14:00 → 16:00 Higgs I

Convener: Gang Li (UMass-Amherst)

zoom

14:00 Searches for Higgs boson pair production with the full LHC Run 2 dataset in ATLAS

The latest results on the production of Higgs boson pairs (HH) in the ATLAS experiment are reported, with emphasis on searches based on the full LHC Run-2 dataset at 13 TeV. In the case of non-resonant HH searches, results are interpreted both in terms of sensitivity to the Standard Model and as limits on kappa_lambda, i.e. a modifier of the Higgs boson self-coupling strength. Searches for new resonances decaying into pairs of Higgs bosons are also reported. Prospects of testing the Higgs boson self-coupling at the High Luminosity LHC (HL-LHC) will also be presented

Speaker: Sean Joseph Gasiorowski (University of Washington (US))

Pheno2021_HH_talk.pdf

14:15 Four-fermion operators in Higgs production and decay

In this talk, we compute the loop corrections to the single Higgs production and decay rates coming from 4 fermion operators of the third generation quarks, which could be tested by current and future ATLAS and CMS measurements of these processes.
These operators have sizeable effects to gluon fusion, $t\bar{t} H$ production cross-sections, as well as Higgs decays to gluons, photons and bottom quarks.
Indeed, we find that for some SM effective Field Theory operators and with the precision of current combined ATLAS and CMS Higgs data, those effects can strengthen the existing bounds from global fits to other processes.
Moreover, since single Higgs processes have been used to constrain the trilinear Higgs self-coupling, we study the correlation between this coupling and the 4 fermion operators fits.

Speaker: Lina Alasfar (Humboldt-Universität zu Berlin)

pheno21-LA-deBlas-Groeber_Talk.pdf

14:30 Higgs Flavor and Multi-Higgs Production

While precision measurements of the Higgs at the LHC continue to confirm its Standard Model-like nature, many of its properties, in particular its couplings to light quarks and to itself, remain essentially unconstrained. Di-Higgs production is well known to be a direct probe of the self coupling, but as I will argue, it is also a powerful probe of Higgs flavor. In models where enhanced Yukawas arise from new scalars with large couplings to light quarks, gigantic di-Higgs — and even tri-Higgs — production rates can be obtained, which can be used to constrain or discover these theories. In this talk, I’ll motivate such theories and describe how they avoid constraints from flavor while enhancing the Higgs Yukawa couplings to light quarks by orders of magnitude. I will then demonstrate that Multi-Higgs production is the most stringent constraint on the Higgs Yukawas in this context, setting limits on the down Yukawa at roughly 30 times its Standard Model value. I will also show that the currently unexplored triple Higgs production topology could be a potential discovery channel for a variety of extended Higgs sectors at the LHC — including not only models where extra Higgses couple to light quarks, but also popular theories where they couple predominantly to the the top quark.

Speaker: Samuel Homiller (Harvard)

210520_hh_flavor_homiller.pdf

14:45 Recent HH results (resonant and non-resonant) in CMS

The recent searches for non-resonant and resonant Higgs pair production with various final states are presented. The analyses are performed using data collected by Compact Muon Solenoid detector with the proton-proton collisions at 13 TeV centre-of-mass energy during the Run2 period. The non-resonant analyses emphasise the results of the cross-section for Higgs pair production and various coupling parameters. For the resonant analyses, the model-independent approach is used, and the status of resolved and boosted topologies is reported together with their BSM models' implication.

Speaker: Ms Lata Panwar (Indian Institute of science (IN))

Pheno2021_LataPanwar.pdf

15:00 Di-Higgs resonance searches in weak boson fusion

Abstract: We examine the weak boson fusion (WBF) production of exotic heavy Higgs states with subsequent decay into 125 GeV Higgs bosons. We include contributions from the gluon fusion production channel and study the interplay of both production modes to improve the discovery potential at the LHC. We observe that in scenarios with isospin singlet mixing in the Higgs sector, resonant di-Higgs production in the WBF mode becomes a phenomenologically relevant channel at small mixing angles, and the inclusion of weak boson sideline can lead to a sizeable improvement in the discovery potential.

Speaker: Rahool Kumar Barman (Indian Association for the Cultivation of Science, Kolkata)

VBF_di-Higgs_Pheno2021.pdf

15:15 CP-Violation in 2HDM is Discrete, but Triple Higgs can Reveal

We distinguish two separate sources of CP-violation in a 2HDM: in the CP properties of the mass eigenstates, and in their bosonic interactions. A systematic study of the interplay between Higgs alignment and CP-violation enables us to define a scenario where departures from Higgs alignment could be present independently of CP-violation. Without recourse to the typically required angular correlations or electric dipole moment signals, and considering current experimental constraints, we suggest a smoking-gun signal of CP-violation in the Higgs-to-Higgs decay, (h3 → h2h1), where h3,h2, and h1 are the heaviest, second heaviest and the SM-like neutral Higgs bosons, respectively. The mere presence of this decay channel, which is non-zero only away from the alignment limit, is sufficient to establish CP-violation in a complex two-Higgs-doublet model. A distinct discovery channel lies in final states with three 125 GeV Higgs bosons, which has yet to be searched for, and could be detected at the high-luminosity LHC.

Speaker: xiaoping wang

pheno-2021-wxp.pdf

15:30 Strong First-Order Electroweak Phase Transitions in the Standard Model with a Singlet Extension

A common assumption about the early universe is that it underwent an electroweak phase transition (EWPT). Though the standard model (SM) is able to restore the electroweak symmetry through a smooth cross over PT, we require a strongly first-order PT to ensure electroweak baryogenesis, requiring us to look at new physics beyond the SM. The simplest case to extend the SM is to add a real singlet field, which allows for a first-order EWPTs (FOEPT) to occur.

Starting with the most general higgs+singlet lagrangian, we fixed four of its coupling constants as functions of the three quartics, the singlet and higg's mass and vacuum expectation value, whose range of values had more experimental motivation than the former. We ran a Monte-Carlo scan over these five free parameters, requiring a FOEPT and a PT strength of $\frac{v_c}{T_c}>1.3$. These points were then passed through the FindBounce package to calculate the nucleation temperature. The resulting parameter space was studied, most notably, we observed the ratio of the triple higgs coupling to the SM value $\left(\kappa =\lambda_3/\lambda_3^{SM}\right)$ take on values between 0.2 and 2.7. The possible values of $\lambda_3$ could serve as motivation for future collider experiments to improve sensitivity in this range when looking at the cross sections of $pp\rightarrow hh$ versus $\lambda_3$.

Speaker: Anthony Hooper (University of Nebraska-Lincoln)

FOEPT_in_the_SM_with_a_Singlet_Extension.A.Hooper.pdf

15:45 Triplet Charged Higgs bosons at the LHC

SU(2) triplet Higgs boson with Y=0 hyper charge breaks the custodial symmetry leading to a tree-level vertex with Z and W boson. This prompts the decays into ZW as compared to t b in a doublet charged Higgs case. However, additional Z_2 symmetry can make this triplet as inert leading to displaced mono/di-leptonic signatures. In case of complex triplet, the model produces a pure triplet dark matter along with a pure and mixed triplet charged Higgs bosons. The last scenario this gives rise to both the displaced and the prompt charged leptons in the final states. We try to distinguish such scenarios at the LHC.

Speaker: Priyotosh Bandyopadhyay (Indian Institute of Technology Hyderabad)

Pheno21.pdf

14:00 → 16:00 SUSY I

Convener: Stephen Martin (Northern Illinois University)

zoom

14:00 Resolving a challenging supersymmetric low-scale seesaw scenario at the ILC

We investigate a scenario inspired by natural supersymmetry, where neutrino data is explained within a low-scale seesaw scenario. For this the Minimal Supersymmetric Standard Model is extended by adding light right-handed neutrinos and their superpartners, the R-sneutrinos. Moreover, we consider the lightest neutralinos to be higgsino-like. We first update a previous analysis and assess to which extent does existing LHC data constrain the allowed slepton masses. Here we find scenarios where sleptons with masses as low as 175 GeV are consistent with existing data. However, we also show that the up-coming run will either discover or rule out sleptons with masses of 300 GeV, even for these challenging scenarios.

We then take a scenario which is on the borderline of observability of the upcoming LHC run assuming a luminosity of 300 fb$^{−1}$. We demonstrate that a prospective international $e^+e^−$ linear collider with a center of mass energy of 1 TeV will be able to discover sleptons in scenarios which are difficult for the LHC. Moreover, we also show that a measurement of the spectrum will be possible within 1-3 per-cent accuracy.

Speaker: Dr Joel Jones-Perez (PUCP)

Pheno2021.pdf

14:15 Flavored Gauge Mediated Supersymmetry Breaking Models with Discrete Non-Abelian Symmetries

We investigate flavored gauge mediation models in which the Higgs and messenger doublets are embedded in multiplets of the discrete non-Abelian symmetry $\mathcal{S}_3$. In these theories, the $\mathcal{S}_3$ symmetry correlates the flavor structure of the quark and lepton Yukawa couplings with the structure of the messenger Yukawa couplings that contribute to the soft supersymmetry breaking mass parameters. We provide a systematic exploration of possible scenarios within this framework that lead to the needed hierarchical quark and charged lepton masses, and examine the resulting phenomenological implications in each case. Quite generally, we find a split spectrum for the superpartner masses compared to flavored gauge mediation models controlled by Abelian symmetries, due to the need in our scenarios for two pairs of messenger fields. We also demonstrate that the flavor violation that is expected in these scenarios generally falls within phenomenologically viable ranges.

Speaker: SHU TIAN EU (University of Wisconsin-Madison)

pheno2021_ShuTianEu_fgm.pdf

14:30 Exploring color-octet scalar parameter space in minimal R-symmetric models

In this work we study the collider phenomenology of color-octet scalars (sgluons) in minimal supersymmetric models endowed with a global continuous R symmetry. We systematically catalog the significant decay channels of scalar and pseudoscalar sgluons and identify novel features that are natural in these models. These include decays in nonstandard diboson channels, such as to a gluon and a photon; three-body decays with considerable branching fractions; and long-lived particles with displaced vertex signatures. We also discuss the single and pair production of these particles and show that they can evade existing constraints from the Large Hadron Collider, to varying extents, in large regions of reasonable parameter space. We find, for instance, that a 725 GeV scalar and a 350 GeV or lighter pseudoscalar can still be accommodated in realistic scenarios.

Speaker: Matthew Smylie (Ohio State University)

color_octet_scalars_talk.pdf

14:45 Color-octet scalars in Dirac gaugino models with broken R symmetry

We present a phenomenological investigation of color-octet
scalars (sgluons) in supersymmetric models with Dirac gaugino masses that feature an explicitly broken $R$ symmetry ($R$-broken models). We have constructed such models by augmenting minimal $R$-symmetric models with a set of supersymmetric and softly supersymmetry-breaking operators that explicitly break $R$ symmetry. We have found new features that appear as a result of $R$ symmetry breaking, including enhancements to extant decay rates, novel tree- and loop-level decays, and improved cross sections of single sgluon production. We have also explored constraints on these models from the Large Hadron Collider. We find that, in general, $R$ symmetry breaking quantitatively affects existing limits on color-octet scalars, closing loopholes for light CP-odd (pseudoscalar) sgluons while perhaps opening one for a light CP-even (scalar) particle. Altogether, scenarios with broken $R$ symmetry and two sgluons at or below the TeV scale can be accommodated by existing searches.

Speaker: Mr Taylor Murphy (Ohio State University)

Murphy_Pheno_2021.pdf

15:00 Landscape Higgs and sparticle mass predictions from a logarithmic soft term distribution

Recent work on calculating string theory landscape statistical predictions for the Higgs and sparticle mass spectrum from an assumed power-law soft term distribution yields an expectation for m(h)~ 125 GeV with sparticles (save light higgsinos) somewhat beyond reach of high-luminosity LHC. A recent examination of statistics of SUSY breaking in IIB string models with stabilized moduli suggests a power-law for models based on KKLT stabilization and uplifting while models based on large-volume scenario (LVS) instead yield an expected logarithmic soft term distribution. We evaluate statistical distributions for Higgs and sparticle masses from the landscape with a log soft term distribution and find the Higgs mass still peaks around ~125 GeV with sparticles beyond LHC reach, albeit with somewhat softer distributions than those arising from a power-law.

Speaker: Shadman Salam (UNIVERSITY OF OKLAHOMA)

Conference_talk_2021.pdf

15:15 Sparticle and Higgs boson masses from the landscape: dynamical vs. spontaneous SUSY breaking

models of dynamical SUSY breaking (DSB)-- with a hidden sector
gauge coupling g^2 scanned uniformly-- lead to gaugino condensation
and a uniform distribution of soft parameters on a log scale.
Then soft terms are expected to be distributed as m_{soft}^{-1}
favoring small values.
A scan of DSB soft terms generally leads to m_h<< 125 GeV
and sparticle masses usually below LHC limits.
Thus, the DSB landscape scenario seems excluded from LHC search results.
An alternative is that the exponential suppression of the weak scale is
set anthropically on the landscape via the atomic principle.

Speaker: Howard Baer (University of Oklahoma)

HBaer_Pheno2021.pdf

15:30 Moduli Stabilisation and the Statistics of SUSY Breaking in the Landscape

The statistics of the supersymmetry breaking scale in the string landscape has been extensively studied in the past finding either a power-law behaviour induced by uniform distributions of F-terms or a logarithmic distribution motivated by dynamical supersymmetry breaking. These studies focused mainly on type IIB flux compactifications but did not systematically incorporate the Kähler moduli. In this talk I point out that the inclusion of the Kähler moduli is crucial to understand the distribution of the supersymmetry breaking scale in the landscape since in general one obtains unstable vacua when the F-terms of the dilaton and the complex structure moduli are larger than the F- terms of the Kähler moduli. After taking Kähler moduli stabilisation into account, we find that the distribution of the gravitino mass and the soft terms is power-law only in KKLT and perturbatively stabilised vacua which therefore favour high scale supersymmetry. On the other hand, LVS vacua feature a logarithmic distribution of soft terms and thus a preference for lower scales of supersymmetry breaking. Whether the landscape of type IIB flux vacua predicts a logarithmic or power-law distribution of the supersymmetry breaking scale thus depends on the relative preponderance of LVS and KKLT vacua.

Speaker: Igor Broeckel (INFN - National Institute for Nuclear Physics)

Pheno_Pittsburgh_broeckel.pdf

15:45 Parameter Inference from Event Ensembles and the Top-Quark Mass

Measurements at colliders are often done by fitting data to simulations, which depend on many physical and unphysical parameters. One example is the top-quark mass, where parameters in simulation must be profiled when fitting the top-quark mass parameter. In particular, the dependence of top-quark mass fits on simulation parameters contributes to the error in the best measurements of the top-quark mass. In this talk, I discuss a simple new fitting method to reduce this error, where regression is done directly on ensembles of events. This method is superior at reducing the top-quark mass uncertainty when compared to both traditional histogram fitting methods as well as the modern ML DCTR method. More generally, machine learning from ensembles for parameter estimation has broad potential for collider physics measurements.

Speaker: Katherine Fraser (Harvard University)

Pheno_2021_TopMassML_Talk.pdf

16:00 → 16:30 Coffee Break

16:30 → 18:30 BSM IV

Convener: Ian Lewis (The University of Kansas)

zoom

16:30 New spin 0 physics from TeV to THz

Fundamental spinless particles are theoretically common yet experimentally rare. This talk presents an overview of my recent phenomenology program probing enigmatic spin 0 dynamics sensitive to new physics. The Higgs self-coupling may remarkably become directly accessible soon but LHC challenges demand continued innovation. Meanwhile, scalar leptons elegantly reconcile the muon g–2 tension and dark matter, and colliding light could enable decisive searches. Tau g–2 is equally important but often overlooked, where new physics modifications generically involve the Higgs field in SMEFT. Finally, axion searches are expanding beyond cavity haloscopes with interesting R&D proposals for broadband sensitivity near the THz window.

Speaker: Jesse Liu (University of Chicago)

Pheno2021-JL-25May2021.pdf

16:45 Complementary exploring low mass vector dark matter, dark photon and dark Z'

In this talk we will discuss a recent study of a low-mass vector dark matter
candidate, $W'$, accompanied by a dark photon and dark $Z'$ in the context of a
simplified gauged two-Higgs-doublet model. The parameter space of the model
(allowed by experimental and theoretical constraints) indicates that a dark $Z'$
can be important for dark matter annihilation while a dark photon is crucial
for direct detection. Furthermore, the currently allowed parameter space can
be probed in the near future by sub-GeV dark matter experiments like CDEX,
NEWS-G and SuperCDMS.

Speaker: Dr Raymundo Ramos (Academia Sinica)

Ramos-pheno2021.pdf

17:00 Searching for dark gauge bosons in next-generation neutrino experiments

Dark gauge bosons including dark photon and $Z'$ have been important players in beyond-the-Standard-Model phenomenology including their potential connection to dark matter. However, their feeble interactions with the Standard Model (SM) particles motivate the use of high-intensity beam-based experiments including neutrino experiments. If neutrinos are non-trivially charged under such dark gauge bosons, the neutrino scattering can be a good channel of investigating their existence, as the scattering may arise via an exchange of a dark gauge boson. In my talk, I will revisit this interesting possibility at a couple of neutrino experiments, DUNE and JSNS$^2$, in the neutrino-electron scattering channel, carefully taking into account the interference effect between the SM processes and new physics contributions, and show that these experiments can probe regions of parameter space that have never been explored before. I will point out that remarkably the destructive interference effect enables us to investigate their parameter space by deficit especially in beam-focusing neutrino experiments such as DUNE.

Speaker: Doojin Kim (Texas A & M University (US))

Presentation_Pheno2021_DoojinKim.pdf

17:15 Disentangling SMEFT operators with future low-energy PVES experiments

We study the potential of future Parity-Violating Electron Scattering (PVES) data to probe the parameter space of the Standard Model Effective Field Theory (SMEFT). We contrast the constraints derived from Drell-Yan data taken at the Large Hadron Collider (LHC) with projections of the planned PVES experiments SoLID and P2. We show that the PVES data can complement the bounds set by the LHC data in the dimension-6 operator space since it probes different combinations of operators than Drell-Yan. The lower characteristic energy of P2 and SoLID also helps disentangle effects of dimension-6 and dimension-8 operators that are difficult to resolve with LHC Drell-Yan data alone.

Speaker: Daniel Wiegand (Northwestern University/ANL)

SMEFT_DanielWiegand.pdf

17:30 Hints of Light New Physics at XENON1T and Muon g-2 Experiments

The dark matter experiment XENON1T reported recently an excess in electronic recoil events with a significance of 3.5 $\sigma$. Also, the Muon g-2 experiment at FERMILAB has confirmed the muon magnetic moment anomaly, raising the significance to 4.2 $\sigma$. Motivated by these experimental results, we interpret the signals in terms of a new light $Z ^\prime$ gauge boson. We discuss how such a light $Z ^\prime$ emerges in a Two Higgs Doublet Model augmented by an abelian gauge symmetry, in agreement with existing bounds.

Speaker: Tessio Melo

Pheno2021_Tessio.pdf

17:45 Model-independent considerations of dark sectors

In this talk, I will present the theoretical framework to probe dark sectors that have portal interactions with the standard model, mediated by irrelevant operators. The focus is to develop a model-independent approach, without any specific model biases. I will focus on dark sectors with approximate conformal dynamics, and elucidate how this allows model-independent bounds to be derived. I will present the constraints from the various class of experiments and explain the procedures and assumptions involved.
The general picture that emerges is that these sectors are poorly constrained at the moment and points to the kind of future experimental facilities that will improve the reach on such dark sectors.
(based on 2012.08537)

Speaker: Rashmish Mishra (Harvard University)

Pheno_DS.pdf

18:00 Searching for soft leptons in compressed spectra with a Boosted Decision Tree

Collider searches for electroweak final states from decays involving narrow mass gaps in a new physics sector are kinematically limited by softness of the scattering products. In a prior study, we required a hard initial state jet in order to boost the visible system, and exploited variations in angular separations to suppress topologically identical backgrounds from WW+jets. Presently, we revisit that analysis to establish how much improvement may be realized by the application of machine learning techniques. We provide a boosted decision tree (BDT) with a combination of high-level (e.g. ditau invariant mass, MT2, cos-theta-star), and low-level (e.g. angular separations, PT ratios) variables. We find that the BDT functions most efficiently if “obvious” event selections (e.g. MET, dilepton Z-window) are applied at the outset, and if individual trainings against similar backgrounds are merged into a composite classification score. This approach yields significantly stronger background suppression and signal retention than could be achieved with manual optimization of cuts.

Speakers: Alyssa Horne (Sam Houston State Univeristy), Mr Marcus Snedeker (Sam Houston State University)

Soft Lepton Searches in Small Mass Gaps Using BDT by Alyssa Horne and Marcus Snedeker.pdf

Soft Lepton Searches in Small Mass Gaps Using BDT by Alyssa Horne and Marcus Snedeker.pptx

18:15 Recent Results of Dark Sector Searches with the BaBar Experiment

Many scenarios of physics beyond the Standard Model predict new particles with masses well below the electroweak scale. Low-energy, high luminosity colliders such as BABAR are ideally suited to discoverthese particles. We present several recent searches for low-mass dark sector particles at BABAR, including leptophilic scalars, self-interacting dark matter, and axion like particles produced in B decays. These examples demonstrate the importance of B-factories in fully exploring low-mass new physics.

Speaker: Bertrand Echenard (California Institute of Technology)

PHENO21-echenard.pdf

16:30 → 18:30 BSM IX

Convener: David Shih (Rutgers University)

zoom

16:30 Forward Physics Facility

A rich physics program remains unexplored in the far-forward region at the LHC. The Forward Physics Facility (FPF) is a proposal to enlarge an existing cavern in the far-forward region of ATLAS to house a suite of experiments with groundbreaking new capabilities for neutrinos, long-lived particle searches, milli-charged particle searches, QCD, dark matter, dark sectors, and cosmic rays. The FPF will be located 500 m from the ATLAS interaction point. It is shielded from the ATLAS interaction point by 100 m of concrete and rock, creating an extremely low-background environment, ideal for many standard model studies and new physics searches. In this talk, we describe the FPF’s location and general features, its physics potential in the HL-LHC era, and topics for further study.

Speaker: Felix Kling (SLAC)

FPF@Pheno-05_21.pdf

16:45 Anomaly-free U(1) and the proton charge radius

We revisit a class of U(1) anomaly-free models that address the proton charge radius discrepancy in light of the latest (g-2) results for the muon.

Speaker: Carlos Alvarado (Tsinghua)

Pheno2021_Alvarado.pdf

17:00 Resonant Leptogenesis and Collider Signals from Discrete Flavor and CP Symmetries

In this talk, I’ll discuss about the production of baryon asymmetry through resonant leptogenesis and phenomological signatures of type-I seesaw scenario with a flavour and a CP symmetry that strongly constrains lepton mixing angles, and both low- and high-energy CP phases. I’ll specially focus on the effect of these symmetries on the collider signals in minimal B-L model and effective neutrino mass in neutrinoless double beta decay, while also requiring production of the experimentally observed baryon asymmetry ($\eta_B$).

Speaker: Garv Chauhan (Washington University in St. Louis)

PPC___Pheno_May_21__Leptogenesis_and_Collider (1).pdf

17:15 The LHC limits on the B-anomalies motivated $U_1$ leptoquark models.

The $U_1$ leptoquark is a suitable candidate to explain the persistent anomalies in the semileptonic decays of the $B$ meson. In this talk, I will discuss how we can use the LHC data to constrain the $U_1$ models. Since the LHC is sensitive towards the leptoquark couplings, rather than the Wilson coefficients, I will discuss some simple scenarios with different couplings that can contribute to the relevant operators and show that the LHC data either rule out or severely constrain these simple $U_1$ scenarios. I will also discuss how the limits can be drawn on scenarios with multiple nonzero couplings from the high-$P_T$ dilepton data. I will show how a TeV range $U_1$ can evade the dilepton limits and the direct search bounds and explain the anomalies.

Speaker: Subhadip Mitra

Pheno2021.pdf

17:30 Unified Framework for B-Anomalies, Muon g-2, and Neutrino Masses

We present a model of radiative neutrino masses which also resolves anomalies reported in $B$-meson decays, $R_{D^{(\star)}}$ and $R_{K^{(\star)}}$, as well as in muon $g-2$ measurement, $\Delta a_\mu$. Neutrino masses arise in the model through loop diagrams involving TeV-scale leptoquark (LQ) scalars $R_2$ and $S_3$. Fits to neutrino oscillation parameters are obtained satisfying all flavor constraints which also explain the anomalies in $R_{D^{(\star)}}$, $R_{K^{(\star)}}$ and $\Delta a_\mu$ within $1\, \sigma$. An isospin-3/2 Higgs quadruplet plays a crucial role in generating neutrino masses; we point out that the doubly-charged scalar contained therein can be produced in the decays of the $S_3$ LQ, which enhances its reach to 1.1 (6.2) TeV at $\sqrt s=14$ TeV high-luminosity LHC ($\sqrt s=100$ TeV FCC-hh). We also find that the same Yukawa couplings responsible for the chirally-enhanced contribution to $\Delta a_\mu$ give rise to new contributions to the SM Higgs decays to muon and tau pairs, with the modifications to the corresponding branching ratios being at (2--6)\% level, which could be tested at future hadron colliders, such as HL-LHC and FCC-hh.

Speaker: Anil Thapa

pheno_2021.pdf

17:45 Bayesian Density Estimation with Voronoi Tessellations on Spatial Data

Relevant information from collision events from the Large Hadron Collider (LHC) and other colliders can be represented as spatial data in the appropriate phase space. Features such as sharp discontinuities in the event number density may signal the presence of new physics. Extraction of features from the data relies upon estimation of the functional value of the underlying distribution. We attempt to use properties of the Voronoi tessellation of the data along with Machine Learning techniques to improve upon traditional methods of density estimation.

Speaker: Alex Roman (University of Florida)

18:00 The Weak EighThe Weak Eightfold Way: $SU(3)_W$ unification of the electroweak interactions

In a recent work, a successful prediction has been made for $\sin^2 \theta_W$ at an energy scale of O(TeV) based on the Dirac quantization condition of an electroweak monopole of the EW-$\nu_R$ model. The fact that such a prediction can be made has prompted the following question: Can $SU(2)$ be unified with $U(1)$ at O(TeV) scale since a prediction for $\sin^2 \theta_W$ necessarily relates the $U(1)$ coupling $g^{\prime}$ to the $SU(2)$ weak coupling $g$? It is shown in this manuscript that this can be accomplished by embedding $SU(2) \times U(1)$ into $SU(3)_W$ (The Weak Eightfold Way) with the following results: 1) The same prediction of the weak mixing angle is obtained; 2) The scalar representations of $SU(3)_W$ contain all those that are needed to build the the EW-$\nu_R$ model and, in particular, the real Higgs triplet used in the construction of the electroweak monopole. 3) Anomaly freedom requires the existence of mirror fermions present in the EW-$\nu_R$ model. 4) Vector-Like Quarks (VLQ) with unconventional electric charges are needed to complete the $SU(3)_W$ representations containing the right-handed up-quarks, with interesting experimental implications such as the prediction of doubly-charged hybrid mesons.

Speaker: Prof. Hung P. Q. (University of Virginia)

PHENO21_pqhung.pdf

18:15 SMEFT Effects on the Angular Orientation of Jet Splitting Products.

We explore features in the orientation of jet splitting products relative to the dijet production plane, with a focus on effects induced by “non-interfering” new physics operators in the standard model effective field theory (SMEFT). We construct an asymmetry variable by integrating the expected angular shape with the differential cross section. This search is sensitive to precisely one CP-conserving Wilson coefficient in the SMEFT, and it is also relatively unaffected by EFT interpretation/theory errors, making it nicely complementary to other searches. We consider competing contributions to the asymmetry from next-to-leading-order effects in QCD and showering of leading-order processes, and characterize signal visibility as a function of luminosity, scale, and systematic uncertainties.

Speakers: Matthew Biasucci (Sam Houston State University), Mr Tao Zhou (Sam Houston State University)

Pheno_presentation.pdf

SMEFT Effects on the Angular Orientation of Jet Splitting Products

16:30 → 18:30 Cosmology IV

https://pitt.zoom.us/j/92596581799

Zoom

16:30 Gravitational Waves as a Big Bang Thermometer

There is a guaranteed background of stochastic gravitational waves produced in the thermal plasma in the early universe. Its energy density per logarithmic frequency interval scales with the maximum temperature which the primordial plasma attained at the beginning of the standard hot big bang era. It peaks in the microwave range, at around $80$ GHz $[106.75/g_{*s}]^{1/3}$, where $g_{*s}$ is the effective number of entropy degrees of freedom in the primordial plasma at the maximum temperature. We present a state-of-the-art prediction of this Cosmic Gravitational Microwave Background (CGMB) for the case of the Standard Model (SM) as well as for several of its extensions. Furthermore, we discuss the current upper limits on the CGMB and the prospects to detect it in laboratory experiments and thus measure the maximum temperature and the effective number of degrees of freedom at the beginning of the hot big bang.

Speaker: Jan Schuette-Engel (University of Illinois at Urbana-Champaign)

GWs_as_HBB_Thermometer.pdf

16:45 Precision gravitational wave spin observables from EFT

Computing sufficiently precise theoretical gravitational wave observables for realistic systems such as compact object binaries remains an essential and notoriously challenging task. In this talk, I will discuss a post-Newtonian effective field theory approach to this problem, focusing specifically on objects with spin. Using this framework, I will present new results at next-to-leading order and compare with those obtained using other formalisms for both spin-orbit and spin-spin contributions. In particular, we obtain the contribution of these effects to the orbital frequency and accumulated orbital phase as well as the adiabatic invariants and flux-balance laws. Importantly, this approach offers a straightforward path forward to systematically push the state-of-the-art to higher orders.

Speaker: Brian Alan Pardo

Pheno2021_BrianPardo.pdf

17:00 Gravitational waves from first-order phase transition during inflation

Abstract: During the inflation era, the properties (such as mass and interactions) of the fields coupled to the inflaton field may change substantially. As a result, drastic phenomena, such as first order phase transitions, may happen. In this talk, I will present simple models that first-order phase transition can happen and finish during inflation. I will discuss the properties of the gravitational wave (GW) signals produced by first-order phase transitions during inflation. I will show that there is a unique oscillatory feature in the GW spectrum. I will also show that we may be able to observe directly such a signal through future terrestrial or spatial GW detectors.

Speaker: Haipeng An (Tsinghua University)

Pheno2021_HaipengAN.pdf

17:15 Gravitational Wave Backgrounds from Low Scale Inflation

While Big Bang cosmology successfully explains much of the history of our universe, there are certain features it does not explain, for example the spatial flatness and uniformity of our universe. One widely studied explanation for these features is cosmological inflation. I will discuss the gravitational wave spectra generated by inflaton field configurations oscillating after inflation for E-Model, T-Model, and additional inflationary models. I will show that these gravitational wave spectra provide access to some inflation models beyond the reach of any planned cosmic microwave background (CMB) experiments, such as LiteBIRD, Simons Observatory, and CMB-S4. Specifically, while these experiments will be able to resolve a tensor-to-scalar ratio ($r$) down to $10^{-3}$, I show that gravitational wave background measurements have the potential to probe certain inflation models for $r$ values down to $10^{-14}$. Importantly, all the gravitational wave spectra from E- and T-model inflation lie in the MHz-GHz frequency range, motivating development of gravitational wave detectors in this range.

Speaker: Simran Nerval (Queen's University)

SimranNerval_Pheno_Pres.pdf

17:30 DarkFlux: a new dark matter phenomenology tool

I introduce DarkFlux, a new tool for the analysis of indirect detection in general Dark Matter models. This tool can compute the flux spectrum for next generation models where Dark Matter annihilates to multiple sets of Standard Model particles. It computes and plots the annihilation ratios scanning over dark matter masses, computes and visualizes the total flux spectrum, and compares models to a set of experimental constraints setting a limit on DM mass for generic user generated models.

Speaker: Linda Carpenter (Ohio State University)

pheno21.pdf

17:45 Can we observe the QCD phase transition-generated gravitational waves through pulsar timing arrays?

We will discuss gravitational wave signals sourced by hydrodynamic and hydromagnetic turbulent sources that might have been present in the early universe at epochs such as the quantum chromodynamic (QCD) phase transition. We consider various models of primordial turbulence: purely hydrodynamical turbulence induced by fluid motions, magnetohydrodynamic (MHD) turbulence dominated either by kinetic or magnetic energy both with and without helicity. We will also address the generation of circularly polarized gravitational waves by parity violating turbulent sources. We will present our results of numerical modeling of the early-universe turbulence and resulting gravitational waves and we will review the signal detection prospects. In particular, we will discuss the potential of explaining the recent observational evidence by NANOGrav collaboration for a stochastic gravitational wave background in the nanohertz frequency range through hydro and hydromagnetic turbulence at the QCD energy scale.

Speaker: Tina Kahniashvili

PHENO2021-Tina_Kahniashvili.pdf

18:00 First result on cosmological first-order phase transitions with LIGO-Virgo's three observing run data

In this talk, I will present the recent result on gravitational waves from cosmological first-order phase transitions obtained using all currently available gravitational wave data from LIGO and Virgo's first three observing runs.

Speaker: Huaike Guo (University of Oklahoma)

Huaike.pdf

18:15 Gravitational waves with astrometric data

Gravitational waves have a periodic effect on the apparent positions of stars on the sky. This effect can be quantified and hence ultra-precise astrometric measurements (like the ones from Gaia) can provide a new method to search for gravitational signals. I will describe the principles which give rise to the astrometric signature of gravitational waves, and examine this result in the context of Einsteinian and alternative polarization states. I will discuss some of the data analysis challenges that will have to be overcome when trying to search for GWs in the extremely large (>$10^9$ stars) Gaia data set, and will present some preliminary estimates of the sensitivity that may be achievable. I will also describe the significance of astrometric measurements for probing stochastic GW backgrounds, and derive the relevant response correlation functions for all polarization modes. If time permits, I will also describe a novel method for constraining the speed of gravity by using astrometry. Throughout, I will keep a parallel between our work and analogous results from the PTA community.

Speaker: Deyan Mihaylov (University of Cambridge)

16:30 → 18:30 DM IV

Convener: Kaustubh Agashe (University of Maryland)

Zoom link DM IV

16:30 Dark Matter with a Bounce

This talk will discuss scenarios where dark matter abundance undergoes a "bounce" - a brief period of increase before thermal freezeout, following the standard exponential Boltzmann suppression - and its related phenomenological aspects.

Speaker: Bibhushan Shakya (Deutsches Elektronen-Synchrotron (DE))

Bibhushan_Shakya_Pheno_2021.pdf

16:45 Electroweak Confinement and $SU(2)_L$ Dark Matter

We consider how a modified cosmological history with a period of electroweak confinement could allow a WIMP dark matter candidate to escape current exclusion bounds. We consider an $SU(2)_L$ vector doublet fermionic dark matter candidate which confines with standard model fermions during this era. These composite particles interact, depleting the dark matter abundance. After these processes freeze out, the electroweak period deconfines and proceeds according to the typical cosmological timeline. We find that this scenario naturally leads to a WIMP dark matter candidate while avoiding current exclusion bounds.

Speakers: Jessica N. Howard (Department of Physics & Astronomy, UC Irvine), Jessica N. Howard (University of California Irvine (US))

Howard_Jessica_Pheno2021.pdf

17:00 Baryogenesis and Dark Matter from Dark, 1st Order Phase Transitions

We present two distinct models which rely on 1st order phase transitions in a dark sector. The first is a minimal model for baryogenesis which employs a new dark SU(2) gauge group with two doublet Higgs bosons, two lepton doublets, and two singlets. The singlets act as a neutrino portal that transfers the generated baryon asymmetry to the Standard Model. The model predicts extra relativistic degrees of freedom, exotic decays of the Higgs and Z bosons, and stochastic gravitational waves detectable by future experiments.

The second model additionally produces (asymmetric) dark matter while the dark sector is expanded to an SU(3)xSU(2)xU(1) gauge group. Dark matter is comprised of dark neutrons or dark protons and pions.This model is highly discoverable at both dark matter direct detection and dark photon search experiments and the strong dark matter self interactions may ameliorate small-scale structure problems.

Speaker: Robert McGehee (University of Michigan)

Robert_McGehee_PHENO21_slides.pdf

17:15 Joint CMB and BBN Constraints for Light Dark Sectors with Dark Radiation

We present novel constraints on sub-GeV dark matter models involving a light particle $\chi$ and a $U(1)'$ dark photon mediator. Using measurements of $N_{\textrm{eff}}$ from the CMB and post-BBN abundances of deuterium and helium-4, we derive constraints on the mass $m_{\chi}$ of the dark matter particle, assuming an MeV-scale mediator mass. Depending on the model parameters, we find that values of $m_{\chi}$ below $\sim 8$-$10$ MeV produce a tension between the predicted values of these CMB and BBN parameters and their experimentally-determined values. We find that this constraint cannot be circumvented by simply adding additional degrees of freedom in the form of dark radiation. Finally, we compare these results to the sensitivities of existing and proposed direct detection experiments, and find an overlap between the regions of parameter space that many of these experiments will probe and the region of parameter space that is constrained by this analysis.

Speaker: Cara Giovanetti (NYU)

Giovanetti_CMBBBNJointConstraints_Pheno.pdf

17:30 A Reconstruction Conjecture: Deciphering the Structure of the Dark Sector from the Matter Power Spectrum

Non-trivial dynamics within the dark sector can give rise to a complicated, non-thermal dark-matter phase-space distribution, which in turn can have a significant impact on the growth of the cosmic structure. In this talk, we explore the cosmological implications of such non-trivial dark-sector dynamics. We show how the non-trivial features in the phase-space distribution can lead to modifications to quantities of structure formation such as the matter power spectrum and the halo mass function. We then examine the extent to which one can address the archaeological "inverse" problem of deciphering the properties of the underlying dark sector from the matter power spectrum. We present a simple one-line conjecture which can be used to “reconstruct” the dark-matter phase-space distribution directly from the shape of the matter power spectrum and show that salient features of the distribution can be successfully reproduced -- even for non-trivial distributions which are highly non-thermal and/or multi-modal. Our conjecture therefore provide an operational tool for probing the dark sector which does not rely on the existence of non-gravitational couplings between dark and visible states.

Speaker: Dr Fei Huang (ITP CAS and UC Irvine)

PHENO_2021_Fei_Huang.pdf

17:45 Extracting Dark-Matter Velocities from Halo Masses: A Reconstruction Conjecture

The distribution of primordial dark-matter velocities can significantly influence the growth of cosmological structure. In principle, one can therefore exploit the halo-mass distribution in order to learn about the dark sector. In practice, however, this task is both theoretically and computationally intractable. In this talk, we present a simple one-line conjecture which can be used to "reconstruct" the primordial dark-matter velocity distribution directly from the shape of the halo-mass function. Although our conjecture is completely heuristic, we show that it successfully reproduces the salient features of the underlying dark-matter velocity distribution --- even for non-trivial distributions which are highly non-thermal and/or multi-modal, such as might occur for non-minimal dark sectors. Our conjecture therefore provides an operational tool for probing the dark sector which does not rely on the existence of non-gravitational couplings between dark and visible states.

Speaker: Kevin Manogue (Lafayette College)

18:00 Superheavy scalar dark matter from gravitational particle production in α-attractor models of inflation

We study the phenomenon of gravitational particle production as applied to a scalar spectator field in the context of α-attractor inflation. Assuming that the scalar has a minimal coupling to gravity, we calculate the abundance of gravitationally-produced particles as a function of the spectator's mass $m_χ$ and the inflaton's α parameter. If the spectator is stable and sufficiently weakly coupled, such that it does not thermalize after reheating, then a population of spin-0 particles is predicted to survive in the universe today, providing a candidate for dark matter. Inhomogeneities in the spatial distribution of dark matter correspond to an isocurvature component, which can be probed by measurements of the cosmic microwave background anisotropies. We calculate the dark matter-photon isocurvature power spectrum and by comparing with upper limits from Planck, we infer constraints on $m_χ$ and α. If the scalar spectator makes up all of the dark matter today, then for α=10 and $T_{RH}=10^4 \mathrm{GeV}$ we obtain $m_χ>1.8×10^{13} \mathrm{GeV}≈1.2 m_ϕ$, where $m_ϕ$ is the inflaton's mass.

Speaker: Siyang Ling (Rice University)

presentation.pdf

presentation.pptx

18:15 Higgs-portal dark matter in brane world cosmology

I will discuss the Higgs-portal dark matter scenario in the 5-dimensional brane world cosmology, such as Randall-Sundrum cosmology and Gauss-Bonnet cosmology.

Speaker: Taoli Liu (the University of Alabama)

PHENO.pdf

16:30 → 18:30 Higgs II

Convener: Samuel Homiller (YITP, Stony Brook)

zoom

16:30 Flavorful Composite Higgs Models

The structures of Yukawa matrices have been a long-standing mystery of the Standard Model. One possible solution is assuming an abelian $U(1)_F$ flavor symmetry and introducing a small parameter $\epsilon$ through the Froggatt-Nielson mechanism. In this talk, I will show how to realize the Froggatt-Nielson mechanism within the framework of composite Higgs models. In this type of model, both the flavor structure and electroweak symmetry breaking originate from TeV-scale strong dynamics. The flavon field arises as a pseudo-Nambu-Goldstone bosons of the broken symmetry and the Froggatt-Nielson fields (vector-like fermions) arise as composite resonances (hadrons) of the strong dynamics.

Speaker: Yi Chung (University of California, Davis)

FCHM_Pheno21.pdf

16:45 Indirect CP probes of the Higgs–top-quark interaction: current LHC constraints and future opportunities

The CP structure of the Higgs boson in its coupling to the particles of the Standard Model is amongst the most important Higgs boson properties which have not yet been constrained with high precision. In this study, all relevant inclusive and differential Higgs boson measurements from the ATLAS and CMS experiments are used to constrain the CP-nature of the top-Yukawa interaction. The model dependence of the constraints is studied by successively allowing for new physics contributions to the couplings of the Higgs boson to massive vector bosons, to photons, and to gluons. In the most general case, we find that the current data still permits a significant CP-odd component in the top-Yukawa coupling. Furthermore, we explore the prospects to further constrain the CP properties of this coupling with future LHC data by determining tH production rates independently from possible accompanying variations of the tt̄H rate. This is achieved via a careful selection of discriminating observables. At the HL-LHC, we find that evidence for tH production at the Standard Model rate can be achieved in the Higgs to diphoton decay channel alone.

Speaker: Henning Bahl (Deutsches Elektronen-Synchrotron DESY)

Pheno2021_Henning_Bahl.pdf

17:00 Resurrecting bbh with Kinematic Shapes

The associated production of a $b\bar{b}$ pair with a Higgs boson could provide an important probe to both the size and the phase of the bottom-quark Yukawa coupling, $y_b$. However, the signal is shrouded by several irreducible background processes. We show that the analysis of kinematic shapes provides us with a concrete prescription for separating the $y_b$-sensitive production modes from both the irreducible and the QCD-QED backgrounds using the $b\bar{b}\gamma\gamma$ final state. We draw a page from game theory and use Shapley values to make Boosted Decision Trees interpretable in terms of kinematic measurables and provide physics insights into the variances in the kinematic shapes of the different channels that help us complete this feat. Adding interpretability to the machine learning algorithm opens up the black-box and allows us to cherry-pick only those kinematic variables that matter most in the analysis. We resurrect the hope of constraining the size and, possibly, the phase of $y_b$ using kinematic shape studies of $b\bar{b}h$ production with the full HL-LHC data and at FCC-hh.

Speaker: Zhuoni Qian (DESY)

PHENO_202105.pdf

17:15 Higgs to Charm Quarks in Vector Boson Fusion plus a Photon

Probing the charm Yukawa coupling is very important to confirm Higgs-fermion interactions and search for deviations from the Standard Model (SM), yet extremely challenging due to enormous QCD background. In this study, we examine the sensitivity of probing Higgs-charm coupling at Large Hadron Collider (LHC) via vector boson fusion with a photon radiation. This additional photon provides an extra handle in triggering and helps suppress gluon-rich background. With a proposed trigger strategy and utilizing multivariate analysis, we find a projected sensitivity of about 5 times the SM charm Yukawa coupling at 95% C.L. at High Luminosity LHC (HL-LHC). Our result is comparable and complementary to existing projections at HL-LHC.

Speaker: Sze Ching Iris Leung (University of Pittsburgh)

Hcc_Pheno2021.pdf

17:30 Softly Shifting Away from Dark Matter Direct Detection: Reviving the Higgs Portal

We propose soft breaking mechanism for dark matter (DM) shift symmetry in a class of composite dark matter models, where both DM and the Higgs boson arise as pseudo Nambu-Goldstone bosons from novel strong dynamics. Our mechanism is utilized to suppress the non-derivative portal coupling between the Higgs boson and DM particle, which can evade the stringent bound of current DM direct detection experiments. Otherwise this non-derivative portal coupling would naturally be at the same order of the Higgs quartic, rendering this class of models under severe crisis. For realizing soft breaking mechanism, we introduce vector-like top partners, dubbed as "softons", to restore the shift symmetry of DM in top Yukawa sector, which however is only broken by the softon masses. The portal coupling would automatically vanish as the shift-symmetry-breaking softon masses approach zero. Specifically we present a proof-of-concept model of soft breaking, based on the coset O(6)/O(5) and the simplest fermion embedding, and study its DM phenomenology, where we show a large amount of novel parameter space is opened up by using the soft breaking mechanism.

Speaker: Ling-Xiao Xu

pheno21_LingXiaoXu.pdf

17:45 Higgs boson couplings to quarks and leptons with the ATLAS experiment

Testing the Yukawa couplings of the Higgs boson to quarks and leptons is important to understand the origin of fermion masses. The talk presents cross section measurements in Higgs boson decays to two bottom quarks or two tau leptons, searches for Higgs boson decays to two charm quarks or two muons, as well as indirect constraints of the charm-Yukawa coupling. The production of Higgs bosons in association with top quarks will also be discussed. These analyses are based on pp collision data collected at 13 TeV.

Speaker: Eleanor Jones (University of Warwick (GB))

Pheno2021.pdf

18:00 A handle on anomalous top-Higgs couplings in top quark pair production through EW loops

In this talk, top quark pair production is proposed as a probe of the CP structure of the top quark Yukawa interaction. Since the top-Higgs coupling enters through Higgs boson loops, a next-to-leading-order calculation is performed in the Standard Model Effective Field Theory in order to include arbitrary CP mixtures. This approach of analyzing Higgs boson degrees of freedom in loops benefits from the large top quark pair production rate and the excellent perturbative control over the theoretical prediction. The resulting sensitivity is contrasted with direct probes with on-shell Higgs boson production in association with a single top quark or top quark pair. Thereby, loop sensitivity is established as a complementary handle to on-shell sensitivity over a wide range of parameter space.

Speaker: Till Martini (HU Berlin)

ewloops.pdf

18:15 Recent Higgs measurements in CMS

Since the discovery of the Higgs boson in 2012, one of the main efforts of the LHC experiments has been to characterize the new particle precisely. This includes measurement of mass, spin properties and couplings as well as differential properties. This talk will emphasize most of the important Higgs analyses decaying to various final states carried by the CMS experiment in recent times.

Speaker: Soumya Mukherjee (Tata Inst. of Fundamental Research (IN))

PHENO-2021-HIGGS-Soumya.pdf

16:30 → 18:30 Neutrino I

Convener: Bei Zhou (Johns Hopkins University)

Zoom link Neutrino I

16:30 Search for heavy neutral lepton production at the NA62 experiment

Searches for heavy neutral lepton production in K+ → e+N and K+ → +N decays using the data set collected by the NA62 experiment at CERN in 2016-18 are presented. Upper limits on the elements of the extended neutrino mixing matrix |Ue4|2 and |U4|2 are established at the levels of 10-9 and 10-8, respectively, improving on the earlier searches for heavy neutral lepton production and decays in the kinematically accessible mass range.

Speaker: Marco Mirra (Universita e sezione INFN di Napoli (IT))

Mirra_Pheno2021.pdf

16:45 The neutrinoless $\beta\beta$ process at the LHC

The Majorana nature of neutrinos and whether lepton number symmetry is conserved are among the most pressing mysteries in physics today. This follows from their widespread implications for cosmology, nuclear physics, and particle physics. Along these lines, searches for the neutrinoless $\beta\beta$ ($0\nu\beta\beta$) decay mode of heavy nuclei are highly sensitive probes of these questions, albeit with important limitations. In this talk we present a new look into the high-energy realization of the $0\nu\beta\beta$ process at the Large Hadron Collider (LHC). As a case study, we focus on the same-sign WW scattering process $W^\pm W^\pm \to \mu^\pm \mu^\pm$, which violates lepton number and is outside the reach of nuclear decay experiments. Whether mediated by heavy Majorana neutrinos or more generally by the Weinberg operator, we find that the LHC offers incredible complementarity to lower energy experiments and further extends the sensitivity to  the nature of neutrinos.

Companion papers:
- https://arxiv.org/abs/2011.02547
- https://arxiv.org/abs/2012.09882

Speaker: Richard Ruiz (Institute of Nuclear Physics (IFJ) PAN)

rruiz_Pheno21_LHCWeinberg.pdf

17:00 Heavy Dirac/Majorana Fermion Decays

If a heavy neutrino is discovered, determining its nature, i.e., whether it is a Dirac or a Majorana fermion, will be at the top of the list of the next questions to ask. A natural way to determine this is to analyze the particle's decays and to observe whether they violate lepton number. However, if the final state includes any light neutrinos, this is impossible. In that event, we may still be able to determine the nature by measuring the distribution of decay events. I will show how this procedure may be performed in the context of three-body decays of heavy neutrinos into a light neutrino and a pair of charged leptons.

Speaker: Kevin Kelly (Fermilab)

KJK_PHENO2021.pdf

17:15 Heavy Neutrinos at Future Linear e+e- Colliders

Neutrinos are probably the most mysterious particles of the Standard Model. The mass hierarchy and oscillations, as well as the nature of their antiparticles, are currently being studied in experiments around the world. Moreover, in many models of the New Physics, baryon asymmetry or dark matter density in the universe are explained by introducing new species of neutrinos. Among others, heavy neutrinos of the Dirac or Majorana nature were proposed to solve problems persistent in the Standard Model. Such neutrinos with masses above the EW scale could be produced at future linear e+e- colliders, like the Compact LInear Collider (CLIC) or the International Linear Collider (ILC).

We studied the possibility of observing production and decays of heavy neutrinos in qql final state at the ILC running at 500 GeV and 1 TeV and the CLIC running at 3 TeV. The analysis is based on the WHIZARD event generation and fast simulation of the detector response with DELPHES. Dirac and Majorana neutrinos with masses from 200 GeV to 3.2 TeV are considered. Estimated limits on the production cross sections and on the neutrino-lepton coupling are compared with the current limits coming from the LHC running at 13 TeV, as well as the expected future limits from hadron colliders. Impact of the gamma-induced backgrounds on the experimental sensitivity is also discussed. Obtained results are stricter than other limit estimates published so far.

Speaker: Mr Krzysztof Mekala (University of Warsaw)

KMekala_PHENO21.pdf

17:30 Neutrino masses from a pseudo-Dirac bino and its detection prospects

We examine the detection prospects for a long-lived biνo, a pseudo-Dirac bino which is responsible for neutrino masses, at the LHC and at dedicated long-lived particle detectors. The biνo arises in U(1)_R-symmetric supersymmetric models where the neutrino masses are generated through higher dimensional operators in an inverse seesaw mechanism. At the LHC the biνo is produced through squark decays and it subsequently decays to quarks, charged leptons and missing energy via its mixing with the Standard Model neutrinos. We consider long-lived biνos which escape the ATLAS or CMS detectors as missing energy and decay to charged leptons inside the proposed long-lived particle detectors FASER, CODEX-b, and MATHUSLA. We find the currently allowed region in the squark-biνo mass parameter space by recasting most recent LHC searches for jets+MET.We also determine the reach of MATHUSLA, CODEX-b and FASER. We find that a large region of parameter space involving squark masses, biνo mass and the messenger scale can be probed with MATHUSLA, ranging from biνo masses of 10 GeV-2 TeV and messenger scales 10^2−10^11TeV for a range of squark masses.

Speaker: Julia Gehrlein

pheno_2021_gehrlein.pdf

17:45 New signatures of decaying HNLs in large scale detectors

Heavy neutral leptons (HNLs) are among the simplest and most natural extensions of the Standard Model; they are widely expected in a range of more complicated dark sector models. At MeV scale masses, HNLs are typically very long lived and can be difficult to search for with laboratory experiments. In this talk I will discus how large volume detectors can search for decaying HNLs produced by neutrinos scattering against terrestrial material (i.e. the entire volume of the Earth). This represents an exciting new detection strategy that can already place new constraints on $\nu_\tau-N$ mass mixing and constraints on dipole portal couplings to all flavors of neutrinos.

Speaker: Ryan Plestid (University of kentucky / Fermilab)

PHENO-2021.pdf

18:00 Supersymmetric minimal U(1)_X model at the TeV scale with right-handed Majorana neutrino dark matter

We propose a supersymmetric extension of the minimal $U(1)_X$ model, along with a new $Z_2$-parity. One of the salient features of this model relates to how the $U(1)_X$ gauge symmetry is broken at the TeV scale. The running of the Majorana coupling of the $Z_2$-even right handed neutrino is shown to become large due to radiative corrections. As a result, this running causes the mass squared of the corresponding right handed sneutrino to negative values and is ultimately responsible for breaking the gauge symmetry. By assigning one right-handed neutrino $Z_2$-odd parity, it can remain a viable dark matter (DM) candidate, despite R-parity being broken. Furthermore, the DM relic abundance receives an enhanced annihilation cross section due to the $U(1)_X$ gauge boson ($Z'$) resonance and is in agreement with the current observations. We have found a complementarity that exists between the observed DM relic abundance and search results for the $Z^\prime$ boson resonance at the Large Hadron Collider that further constrains the parameter space of our $U(1)_X$ model.

Speaker: Desmond Villalba (Drury University)

DV21Talk.pdf

18:15 Phenomenology of the minimal inverse seesaw model with Abelian flavour symmetries

We study the phenomenology of the minimal $(2,2)$ inverse-seesaw model supplemented with Abelian flavour symmetries. To ensure maximal predictability, we establish the most restrictive flavour patterns which can be realised by those symmetries. This setup requires adding an extra scalar doublet and two complex scalar singlets to the Standard Model, paving the way to implement spontaneous CP violation. It is shown that such CP-violating effects can be successfully communicated to the lepton sector through couplings of the scalar singlets to the new sterile fermions. The Majorana and Dirac CP phases turn out to be related, and the active-sterile neutrino mixing is determined by the active neutrino masses, mixing angles and CP phases. We investigate the constraints imposed on the model by the current experimental limits on lepton flavour-violating decays, especially those on the branching ratio $\text{BR}(\mu\rightarrow e \gamma)$ and the capture rate $\text{CR}(\mu-e,{\rm Au})$. The prospects to further test the framework put forward in this work are also discussed in view of the projected sensitivities of future experimental searches sensitive to the presence of heavy sterile neutrinos. Namely, we investigate at which extent upcoming searches for $\mu\rightarrow e \gamma$, $\mu \rightarrow 3e$ and $\mu-e$ conversion in nuclei will be able to test our model, and how complementary will future high-energy collider and beam-dump experiments be in that task.

Speaker: Mr Henrique Brito Câmara (CFTP/IST, U.Lisboa)

PHENO_2021_H.B.Câmara.pdf

16:30 → 18:30 SUSY II

Convener: Howard Baer (University of Oklahoma)

Zoom

16:30 Exploring Uncharted Soft Displaced Vertices in Open Data

We study a challenging signature in collider physics, that the final state contains soft and displaced tracks, with the help of the CMS Open Data. This signature is of particular interest since it corresponds to a well-motivated dark matter coannihilation regime. We propose to search for signals in monojet plus missing energy events, exploiting displaced vertices reconstructed from soft tracks. We perform such a search in the 8 TeV CMS Open Data events with a luminosity of 11.6 fb$^{-1}$ and obtain 95\% confidence level limit on the plane of top squark mass $m_{\tilde t}$ and lightest neutralino mass $m_{\chi^0}$. In the region $m_{\tilde t} - m_{\chi^0} \approx 15-30$ GeV, we exclude $m_{\tilde t} < 350$ GeV, which is more stringent than the ATLAS and CMS results using 8 TeV data with about 20 fb$^{-1}$ luminosity. Our study shows that the CMS Open Data can be a powerful tool to help theorists study efficiencies and backgrounds of non-conventional new physics searches.

Speaker: Daneng Yang (Department of Physics, Tsinghua University (CN))

Daneng_Yang_opendataPheno2021.pdf

16:45 Higgsino Dark Matter in Electron Electric Dipole Moments

Higgsinos are a particularly compelling form of dark matter, and are on the verge of detection by multiple current experimental avenues. They can arise in models with decoupled scalars that enjoy the benefits of depending on very few parameters while still explaining gauge coupling unification, dark matter, and most of the hierarchy between the Planck and electroweak scales, and they remain undetected to past experiments. My talk will cover the reach for current and upcoming electron electric dipole moment experiments to observe higgsino dark matter models.

Speaker: Benjamin Sheff

Sheff_Pheno.pdf

17:00 Distribution of supersymmetry mu parameter and Peccei-Quinn scale f_a from the landscape

A scan of soft SUSY breaking parameters within the string theory landscape with the MSSM assumed as the low energy effective field theory– using a power-law draw to large soft terms coupled with an anthropic selection of a derived weak scale to be within a factor four of our measured value– predicts a peak probability of $m_h \simeq 125 \text{ GeV}$ with sparticles masses typically beyond the reach of LHC Run 2. Such multiverse simulations usually assume a fixed value of the SUSY conserving superpotential $\mu$ parameter to be within the assumed anthropic range, $\mu < \sim 350 \text{ GeV}$. However, depending on the assumed solution to the SUSY $\mu$ problem, the expected $\mu$ term distribution can actually be derived. We examine two solutions to the SUSY $\mu$ problem. The first is the gravity-safe Peccei-Quinn (GSPQ) model based on an assumed $\mathbb{Z}_{24}^R$ discrete $R$-symmetry which allows a gravity-safe accidental, approximate Peccei-Quinn global symmetry to emerge which also solves the strong CP problem. The second case is the Giudice-Masiero solution wherein the $\mu$ term effectively acts as a soft term and has a linear draw to large values. For the first case, we also present the expected landscape distribution for the PQ scale $f_a$; in this case, weak scale anthropics limits its range to the cosmological sweet zone of around $f_a ∼ 10^{11} \text{ GeV}$.

Speaker: Robert Wiley Deal (University of Oklahoma-Norman)

Pheno2021_RWD.pdf

17:15 A Supersymmetric Flavor Clockwork

Clockwork models can explain the flavor hierarchies in the Standard Model quark and lepton spectrum.
We construct supersymmetric versions of such flavor clockwork models. The zero modes of the clockwork are identified with the fermions and sfermions of the Minimal Supersymmetric Standard Model. In addition to generating a hierarchical fermion spectrum, the clockwork also predicts a specific flavor structure for the soft SUSY breaking sfermion masses. We find sizeable flavor mixing among first and second generation quarks. Constraints from Kaon oscillations require the masses of either squarks or gluinos to be above a scale of $\sim 3$ PeV.

Speaker: Sri Aditya Gadam (University of California, Santa Cruz)

Flavorful_Super_Clockwork.pdf

17:30 Searches for strong production of supersymmetric particles with the ATLAS detector

Supersymmetry (SUSY) provides elegant solutions to several problems in the Standard Model, and searches for SUSY particles are an important component of the LHC physics program. Naturalness arguments for weak-scale supersymmetry favour supersymmetric partners of the gluons and third generation quarks with masses light enough to be produced at the LHC. This talk will present the latest results of searches conducted by the ATLAS experiment which target gluino and squark production, including stop and sbottom, in a variety of decay modes. It covers both R-parity conserving models that predict dark matter candidates and R-parity violating models that typically lead to high-multiplicity final states without large missing transverse momentum.

Speaker: Yang Liu (Nanjing University (CN))

Strong SUSY Searches in ATLAS.pdf

17:45 Searches for third generation SUSY particles with the CMS experiment

The latest results from searches for third generation supersymmetric particles with the CMS experiment will be presented. The analyses are based on the full dataset of pp collisions recorded at sqrt(s) = 13 TeV during the LHC Run 2.

Speaker: Jon Wilson (Baylor University (US))

JSW-CMS-SUSY-3rd-gen.pdf

18:00 Searches for electroweak production of supersymmetric particles with the ATLAS detector

The direct production of electroweak SUSY particles, including sleptons, charginos, and neutralinos, is a particularly interesting area with connections to dark matter and the naturalness of the Higgs mass. The small production cross sections lead to difficult searches, despite relatively clean final states. This talk will highlight the most recent results of searches performed by the ATLAS experiment for supersymmetric particles produced via electroweak processes, including analyses targeting small mass splittings between SUSY particles. Models are targeted in both R-parity conserving as well as R-parity violating scenarios.

Speaker: Batool Safarzadeh Samani (University of Sussex (GB))

Pheno_EWK.pdf

18:15 CP-Violating Invariants in the SMEFT

In the Standard Model, CP violation in the Electroweak sector is parametrized by the Jarlskog Invariant. This is the flavor invariant sensitive to CP violation with the least number of Yukawa matrices that can be built. When higher dimensional operators are allowed, and the Standard Model Effective Field Theory is constructed, numerous new sources for CP violation can appear. However, the description of CP violation as a collective effect, present in the SM, is inherited by its Effective extension. Here, I will discuss how such a behaviour can be consistently captured, at dimension 6, by flavor invariant, CP violating objects, linear in the Wilson coefficients. Such a description ensures that CP violation in the SMEFT is treated in a basis independent manner. In particular, I claim these are the objects that have to vanish, together with the SM Jarlskog Invariant, for CP to be conserved, and viceversa. The scaling properties of these invariants demonstrates that, while CP is not an accidental symmetry of the Standard Model, its breaking is accidentally small at the renormalizable level. Implications for specific flavor models, such as MFV, will be addressed.

Speaker: Emanuele Gendy Abd El Sayed (DESY)

pheno_pittsburgh.pdf

18:45 → 20:00 Virtual Cocktail

Wednesday 26 May

08:45 → 10:30 Plenary: V

https://pitt.zoom.us/j/93951025550

Convener: Kaladi Babu (Oklahoma State University)

zoom

08:45 Perspectives on neutrino physics

Speaker: Regina Abby Rameika (Fermi National Accelerator Lab. (US))

PHENO_Main.pdf

09:20 Deep Learning Landscapes

Speaker: James Halverson

PHENO 2021 (2).pdf

09:55 Physics opportunities at future colliders

Speakers: Patrick Meade (Stony Brook University), Patrick Meade

PHENO2021.pdf

10:30 → 11:00 Coffee break

11:00 → 12:45 Plenary: VI

https://pitt.zoom.us/j/93951025550

Conveners: R Sekhar Chivukula (UC San Diego), R. Sekhar Chivukula (UC San Diego)

zoom

11:00 Scattering amplitudes and more

Speaker: Henriette Elvang (University of Michigan)

genKLT-final.pdf

11:35 General Neutrino Interactions

Speaker: Danny Marfatia

Pheno.pdf

12:10 New perspectives in particle physics

Speaker: Richard Keith Ellis (University of Durham (GB))

Future_Perspectives_Ellis.pdf

12:45 → 14:00 Lunch

14:00 → 16:00 BSM V

Convener: Tathagata Ghosh (University of Hawaii at Manoa)

zoom

14:00 The THDMa revisited

The THDMa is a new physics model that extends the scalar sector of the Standard Model by an additional doublet as well as a pseudoscalar singlet and allows for mixing between all possible scalar states. In the gauge eigenbasis, the additional pseudoscalar serves as a portal to the dark sector, with a priori any dark matter spins states. The option where dark matter is fermionic is currently one of the standard benchmarks for the experimental collaborations, and several searches at the LHC constrain the corresponding parameter space. However, most current studies constrain regions in parameter space by setting all but 2 of the 12 free parameters to fixed values. I discuss a generic scan on this model, allowing all parameters to float. All current theoretical and experimental constraints are taken into account, including bounds from current searches, recent results from B-physics, as well as bounds from astroparticle physics. We identify regions in the parameter space which are still allowed after these have been applied and which might be interesting for an investigation at current and future collider machines.

Speaker: Tania Robens (Rudjer Boskovic Institute (HR))

robens_pheno21.pdf

14:15 Probing the minimal $U(1)_X$ model at future electron-positron colliders via the fermion pair-production channel

The general $U(1)_𝑋$ extension of the Standard Model (SM) is a well motivated scenario which has a plenty of new physics options. Such a model is anomaly free which requires to add three generations of the SM singlet right-handed neutrinos (RHNs) which naturally generates the light neutrino masses by the seesaw mechanism.This offers interesting phenomenological aspects in the model. In addition to that the model is equipped with a beyond the SM (BSM) neutral gauge boson, $𝑍^\prime$ which interacts with the SM and BSM particles showing a variety of new physics driven signatures. After the anomaly cancellation the $U(1)_𝑋$ charge of the particles are expressed in terms of the SM Higgs doublet and the SM Higgs singlet which allows us to study the interaction of the fermions with the $𝑍^\prime$.In this paper we investigate the pair production mechanism of the different charged through the photon, $𝑍$ and $𝑍^\prime$ boson exchange processes at the electron-positron $(𝑒^-𝑒^+)$.The angular distributions, forward-backward $(\mathcal{A}_{FB})$, left-right $(\mathcal{A}_{LR})$ and left-right forward-backward $(\mathcal{A}_{LR,FB})$ asymmetries of the different charged fermion pair productions show substantial deviation from the SM results.

Speaker: Arindam Das (Kyungpook National University)

ADAS_PHENO2021.pdf

14:30 Multi-lepton anomalies at the LHC and implications

Based on a number of features from proton-proton collisions taken during Run 1 data taking period at the LHC, a boson with a mass around the Electro-Weak scale was postulated such that a significant fraction of its decays would comprise the Standard Model (SM) Higgs boson and an additional scalar, S. One of the implications of a simplified model, where S is treated a SM Higgs boson, is the anomalous production of high transverse momentum leptons. Corners of the phase-space are fixed according to the model parameters derived in 2017 without additional tuning, in order to nullify potential look-else-where effects or selection biases. A combined study of subsequent data is indicative of significant discrepancies between the data and SM Monte Carlos in a variety of final states involving multiple leptons with and without b-quarks. These discrepancies appear in corners of the phase-space where different SM processes dominate, indicating that the potential mismodeling of a particular SM process is unlikely to explain them. The internal consistency of these anomalies and their interpretation in the framework of the original hypothesis is quantified. Implications on the Higgs boson measurements, muon g-2 and and astrophysics are also discussed.

Speaker: Prof. Bruce Mellado (University of the Witwatersrand and iThemba LABS)

Pheno2021_Multilepton_LHC_260521.pdf

14:45 Phenomenology at the LHC of composite particles from strongly interacting Standard Model fermions via four-fermion operators of Nambu-Jona-Lasinio type

In this work (arXiv: https://arxiv.org/abs/1810.11420, DOI: 10.1140/epjc/s10052-020-7822-0) a new physics scenario shows that four-fermion operators of Nambu-Jona-Lasinio (NJL) type have a strong-coupling UV fixed point, where composite fermions F (bosons Π) form as bound states of three (two) SM elementary fermions and they couple to their constituents via effective contact interactions at the composite scale Λ≈O(TeV). We present a phenomenological study to investigate such composite particles at the LHC by computing the production cross sections and decay widths of composite fermions in the context of the relevant experiments at the LHC with pp collisions at √s=13 TeV and √s=14 TeV. Systematically examining all the different composite particles F and the signatures with which they can manifest, we found a vast spectrum of composite particles F that has not yet been explored at the LHC. Recasting the recent CMS results of the resonant channel pp→e+F→e+e−qq¯′, we find that the composite fermion mass mF below 4.25 TeV is excluded for Λ/mF = 1. We further highlight the region of parameter space where this specific composite particle F can appear using 3 ab−1, expected by the High-Luminosity LHC, computing 3 and 5 σ contour plots of its statistical significance.

Speaker: Francesco Romeo (Vanderbilt University)

Pheno2021_Composite_Fermions.pdf

15:00 (New) Physics at a multi-TeV Muon Collider

We discuss the physics potential of a multi-TeV muon collider. We present the results for the main SM processes together with popular BSM models, emphasizing the annihilation and VBF regime at very-high energies. We also discuss some preliminary results about the Effective Vector Boson Approximation and its implementation in MadGraph5_aMC@NLO.

Speaker: Antonio Costantini (INFN)

Pheno_2021_Costantini.pdf

15:15 Searching for New Physics at Muon Colliders

A high energy muon collider can provide new and complementary discovery potential to the LHC or future hadron colliders. Leptoquarks are a motivated class of exotic new physics models, with distinct production channels at hadron and lepton machines. We study a vector leptoquark model at a muon collider with $\sqrt{s}$=3,14 TeV within a set of both UV and phenomenologically motivated flavor scenarios. We compute which production mechanism has the greatest reach for various values of the leptoquark mass and the coupling between leptoquark and Standard Model fermions. We find that we can probe leptoquark masses up to an order of magnitude beyond s√ with perturbative couplings. Additionally, we can also probe regions of parameter space unavailable to flavor experiments. In particular, all of the parameter space of interest to explain recent low-energy anomalies in B meson decays would be covered even by a $\sqrt{s}$=3 TeV collider.

Speaker: Cari Cesarotti (Harvard University)

phenoLQ_2021.pdf

15:30 Renormalization of scalar EFTs at higher orders

Because of its ability to systematically capture beyond Standard Model (SM) effects, effective field theory (EFT) has received much attention in phenomenological analyses of e.g. LHC data. Recent theoretical studies have focused on operator basis construction and loop level calculations in EFTs. In this work, we construct the complete basis for scalar $\phi^4$ EFT up to mass dimension 12, with the help of the Hilbert series method. We present high loop calculations (up to 5 loop), and find unexpected zeros and interesting symmetric structures in the anomalous dimension matrix. The method we use can be extended to more general theories, i.e. SMEFT and be applied in high precision measurements within the SMEFT framework at the LHC.

Speaker: Weiguang Cao (Kavli IPMU)

Renormalization for scalar EFTs.pdf

15:45 Unveiling the Higgs at FCC-hh with new diboson precision measurements.

The lack of evidence of New Physics coming from direct searches of resonances at the LHC calls for an increase in efforts to devise new observables that can indirectly probe New Physics. Additionally, the future FCC-hh will make available new processes, inaccessible so far due to their low number of events. Studying the high transverse momentum distribution of diboson production processes at FCC-hh is then an interesting path to explore. I will discuss how the diboson processes Wh and Zh, with leptonic decays for W and Z and the Higgs decaying to 2 photons, will allow us to know more about the physics of the Higgs boson in an EFT framework. I will also focus on how doubly differential distributions give us access to higher-dimension operators that, otherwise, would require more specific observables. Finally, I will show how these processes will help to improve the bounds on aTGCs obtained from electron-positron colliders.

Speaker: Alejo Rossia (Deutsches Elektronen-Synchrotron DESY)

Rossia_Vh_Pheno_2021_PDF.pdf

14:00 → 16:00 Cosmology V

https://pitt.zoom.us/j/93567042779

Zoom

14:00 Black Hole Production of Monopoles the Early Universe

In the early universe, black holes can easily produce monopoles. Via Hawking radiation, evaporating black holes heat up the surrounding plasma and create a temperature profile around the black hole that features symmetry restoration near the center. Eventually, this region cools off and undergoes the Kibble mechansim, producing monopoles. We demonstrate that this process can very efficiently produce monopoles. In the case where black holes reheat the universe, reheat temperatures above 100 GeV can already lead to monopoles overclosing the universe.

Speaker: Saurav Das (University of Maryland College Park)

Monopole.pdf

14:15 Dark matter and dark radiation from primordial black holes

Primordial black holes (PBHs) lighter than $5\times 10^{14}\,$g cannot constitude the dark matter (DM) because they are already evaporated, but they are constrained by early universe phenomena (BBN, CMB). PBHs lighter than $10^9\,$g, however, are at present mostly unconstrained. In this talk, we will present scenarios where light (spinning) PBHs with $M_\text{PBH}<10^9\,$g evaporate in the early universe before BBN and produce either a warm DM particle or dark radiation. We will then confront the predictions on respectively structure formation and $\Delta N_\text{eff}$ to observations to conclude with Hawking radiation constraints on these light PBHs.

Speaker: Jeremy Auffinger (Institut d'Astrophysique de Paris)

main.pdf

14:30 Precision Calculation of Dark Radiation from Spinning Primordial Black Holes and Early Matter Dominated Eras

We present precision calculations of dark radiation in the form of gravitons coming from Hawking evaporation of spinning primordial black holes (PBHs) in the early Universe. Our calculation incorporates a careful treatment of extended spin distributions of a population of PBHs, the PBH reheating temperature, and the number of relativistic degrees of freedom. We compare our precision results with those existing in the literature, and show constraints on PBHs from current bounds on dark radiation from BBN and the CMB, as well as the projected sensitivity of CMB Stage 4 experiments.As an application, we consider the case of PBHs formed during an early matter-dominated era (EMDE). We calculate graviton production from various PBH spin distributions pertinent to EMDEs, and find that PBHs in the entire mass range up to $10^9\,$g will be constrained by measurements from CMB Stage 4 experiments, assuming PBHs come to dominate the Universe prior to Hawking evaporation. We also find that for PBHs with monochromatic spins $a^*>0.81$, all PBH masses in the range $10^{-1}\,{\rm g} < M_{\rm BH} <10^9\,{\rm g}$ will be probed by CMB Stage 4 experiments.

Speaker: Barmak Shams Es Haghi (University of Utah)

Pheno2021.pdf

14:45 Signals of primordial black holes at gravitational wave interferometers

Primordial black holes (PBHs) can form as a result of primordial scalar perturbations at small scales. This PBH formation scenario has associated gravitational wave (GW) signatures from second-order GWs induced by the primordial curvature perturbation, and from second-order GWs produced by the gravitational potential of the PBHs themselves. We investigate the ability of next generation GW experiments, including BBO, LISA, and CE, to probe this PBH formation scenario in a wide mass range ($10 - 10^{27}$g). Measuring the stochastic GW background with GW observatories can constrain the allowed parameter space of PBHs including a previously unconstrained region where light PBHs ($<10^9$g) temporarily dominate the energy density of the universe before evaporating. We also show how PBH formation impacts the reach of GW observatories to the primordial power spectrum and provide constraints implied by existing PBH bounds.

Speaker: Ethan Villarama (UCSD)

Pheno_2021_EV_V2.pdf

15:00 Dark Black Holes in the Mass Gap

According to our current models of stellar collapse, stars in the mass range ~64-135 M⊙ undergo pair-instability supernovae, leaving behind no remnant. However, in 2019 LIGO and Virgo detected a black hole merger event with a high probability that the mass of the heavier black hole was within this pair-instability mass gap, motivating the exploration of novel black hole formation mechanisms. We hypothesize that clumps of gas in an atomic dark sector could cool efficiently enough to form a black hole within the mass gap. As a first step, we investigate this scenario with Standard Model parameters by simulating a star without nuclear reactions using the MESA stellar evolution code. Generalizing this investigation to the dark QED sector, we expand the parameter space using a combination of analytical and numerical methods.

Speaker: Lillian Santos-Olmsted (University of California, Santa Cruz)

15:15 Phenomenology of magnetic black holes with electroweak-symmetric coronas

Magnetically charged black holes (MBHs) are interesting solutions of the Standard Model and general relativity. They may possess a “hairy” electroweak-symmetric corona outside the event horizon, which speeds up their Hawking radiation and leads them to become nearly extremal on short timescales. Their masses could range from the Planck scale up to the Earth mass. We study various methods to search for primordially produced MBHs and estimate the upper limits on their abundance. We revisit the Parker bound on magnetic monopoles and show that it can be extended by several orders of magnitude using the large-scale coherent magnetic fields in Andromeda. This sets a mass-independent constraint that MBHs have an abundance less than $4 × 10^{−4}$ times that of dark matter. MBHs can also be captured in astrophysical systems like the Sun, the Earth, or neutron stars. There, they can become non-extremal either from merging with an oppositely charged MBH or absorbing nucleons. The resulting Hawking radiation can be detected as neutrinos, photons, or heat. High-energy neutrino searches in particular can set a stronger bound than the Parker bound for some MBH masses, down to an abundance $10^{−7}$ of dark matter.

Speaker: Mrunal Korwar (University of Wisconsin-Madison)

PHENO2021_MRUNAL.pdf

PHENO2021_MRUNAL.pptx

15:30 The Price of Curiosity: Information Recovery in de Sitter Space

Recent works have revealed that the fine-grained entropy of a non-gravitating subsystem, when entangled with a gravitating region, can receive contributions from so-called quantum extremal islands. Applied to black holes, this reproduces the unitary Page curve for Hawking radiation. In this talk, I will show how these results can be applied to the thermal radiation measured by a static observer in de Sitter space. Focusing on JT gravity, I will emphasize the necessity of going beyond the thermal equilibrium of the Bunch-Davies state. We will see that a quantum extremal island can contribute to the fine-grained entropy, suggesting unitarity of the radiation, but this comes at a price: when the island appears a singularity forms that a static observer will eventually hit.

Speaker: Lars Aalsma

Pheno 2021.05.26.pdf

15:45 Hot Qubits on the Horizon

Perturbation theory for gravitating quantum systems tends to fail at very late times (a type of perturbative breakdown known as secular growth). We argue that gravity is best treated as a medium/environment in such situations, where reliable late-time predictions can be made using tools borrowed from quantum optics. To show how this works, we study the explicit example of a qubit hovering just outside the event horizon of a Schwarzschild black hole (coupled to a real scalar field) and reliably extract the late-time behaviour for the qubit state. At very late times, the so-called Unruh-DeWitt detector is shown to asymptote to a thermal state at the Hawking temperature.

Speaker: Gregory Kaplanek

Hot Qubits on the Horizon - Greg Kaplanek.pdf

14:00 → 16:00 DM V

Conveners: Nobuchika Okada (University of Alabama), Nobuchika Okada (U. Alabama )

Zoom link DM V

14:00 Low-mass inelastic dark matter direct detection via the Migdal effect

We consider searches for the inelastic scattering of low-mass dark matter against nuclei at direct detection experiments, using the Migdal effect. We find that there are degeneracies between the dark matter mass and the mass splitting that are difficult to break. Using XENON1T data we set bounds on a previously unexplored region of the inelastic dark matter parameter space. For the case of exothermic scattering, we find that the Migdal effect allows xenon-based detectors to have sensitivity to dark matter with ${\cal O}({\rm MeV})$ mass, far beyond what can be obtained with nuclear recoils.

Speaker: Jason Kumar

Pheno2021a.pdf

14:15 Dark Matter Daily Modulation With Anisotropic Organic Crystals

Aromatic organic compounds, because of their small excitation energies $\sim \mathcal O$(few eV) and scintillating properties, are promising targets for detecting dark matter of mass $\sim \mathcal O$(few MeV). Additionally, their planar molecular structures lead to large anisotropies in the electronic wavefunctions, yielding a significant daily modulation in the event rate expected to be observed in crystals of these molecules. We characterize the daily modulation rate of dark matter interacting with an anisotropic scintillating organic crystal such as trans-stilbene, and show that daily modulation is an $\sim \mathcal O$(1) fraction of the total rate for small DM masses and comparable to, or larger than, the $\sim 10\%$ annual modulation fraction at large DM masses. As we discuss in detail, this modulation provides significant leverage for detecting or excluding dark matter scattering, even in the presence of a non-negligible background rate. Assuming a non-modulating background rate of 1/min/kg that scales with total exposure, we find that a 100${\rm kg \cdot yr}$ experiment is sensitive to the cross section corresponding to the correct relic density for dark matter masses between $1.3-14\;\rm{MeV}$ ($1.5-1000\;\rm{MeV}$) if dark matter interacts via a heavy (light) mediator. This modulation can be understood using an effective velocity scale $v^* = \Delta E/q^*$, where $\Delta E$ is the electronic transition energy and $q^*$ is a characteristic momentum scale of the electronic orbitals. We also characterize promising future directions for development of scintillating organic crystals as dark matter detectors.

Speaker: Dr Carlos Blanco (Princeton University & Stockholm University)

14:30 Sources of Low-energy Events in Sub-GeV Dark Matter Detectors

We point out several unexplored low-energy backgrounds to sub-GeV dark matter searches, which arise from high-energy particles of cosmic or radioactive origin that interact with detector materials. In this talk, I will focus on Cherenkov radiation and luminescence from electron-hole pair recombination. I will show that these processes provide plausible explanations of the observed events at SENSEI and SuperCDMS HVeV. A detailed simulation of these events at SENSEI will be presented in the companion talk. We also propose several important design strategies to mitigate such backgrounds, which could have a significant impact on the design of future dark matter experiments.

Speaker: Peizhi Du (Stony Brook University)

Pheno 2021.pdf

14:45 Sources of Low-Energy Backgrounds in SENSEI

Several low-threshold detectors looking for sub-GeV dark matter have observed a large rate of low-energy events. The SENSEI experiment, which looks for small ionization signals in Silicon Skipper CCD to search for sub-GeV dark matter, has also observed a large single-electron event rate which cannot be explained by previously explored backgrounds. In this talk, I will focus on radiative backgrounds like Cherenkov radiation and Luminescence from electron-hole recombination in the SENSEI detector. With results from a detailed simulation of these backgrounds, I will show that a significant fraction of the observed single-electron rate can be attributed to these radiative processes.

Speaker: Mukul Sholapurkar (Stony Brook University)

pheno_21_mukul.pdf

15:00 Superfluid EFT for sub-GeV dark matter detection

The detection of low mass dark matter is under development with the advancement of experiment techniques. The superfluid helium-4 detector covers an extensive detection range from DM mass keV to GeV among the setups. I will present a complete theoretical framework for all processes within the superfluid to fill in the missing theory for sub-GeV DM detection. First, we use effective field theories to construct the interaction Lagrangian between quasi-particles. Second, we use a U(1) gauge spontaneous breaking and current element method to derive the interaction between test particles and quasi-particles. In the end, I will discuss relevant cross-sections and decay rates.

Speaker: Yining You (University of Florida)

pheno21_Yining.pdf

15:15 Etching Plastic Searches for Dark Matter

Large panels of etched plastic, situated aboard the Skylab Space Station and inside the Ohya quarry near Tokyo, have been used to set limits on fluxes of cosmogenic particles. These plastic particle track detectors also provide the best sensitivity for some heavy dark matter that interacts strongly with nuclei. We revisit prior dark matter bounds from Skylab, and incorporate geometry-dependent thresholds, a halo velocity distribution, and a complete accounting of observed through-going particle fluxes. These considerations reduce the Skylab bound's mass range by a few orders of magnitude. However, a new analysis of Ohya data covers a portion of the prior Skylab bound, and excludes dark matter masses up to the Planck mass. Prospects for future etched plastic dark matter searches are discussed.

Speaker: Amit Bhoonah

Pheno2021.key

Pheno2021.key

15:30 Self-interacting Inelastic Dark Matter in the Light of XENON1T Excess

We propose a self-interacting inelastic dark matter (DM) scenario as a possible origin of the recently reported excess of electron recoil events by the XENON1T experiment. Two quasi-degenerate Majorana fermion DM interact within themselves via a light hidden sector massive gauge boson and with the standard model particles via gauge kinetic mixing. We also consider an additional long-lived singlet scalar which helps in realising correct dark matter relic abundance via a hybrid setup comprising of both freeze-in and freeze-out mechanisms. While being consistent with the required DM phenomenology along with sufficient self-interactions to address the small scale issues of cold dark matter, the model with GeV scale DM can explain the XENON1T excess via inelastic down scattering of heavier DM component into the lighter one. All these requirements leave a very tiny parameter space keeping the model very predictive for near future experiments.

Speaker: Manoranjan Dutta (Indian Institute of Technology Hyderabad)

pheno21_manoranjan.pdf

15:45 Muon $(g-2)$ and XENON1T Excess with Dark Matter in $L_{\mu}-L_{\tau}$ Model

Motivated by the growing evidence for lepton flavour universality violation after the first results from Fermilab's muon $(g-2)$ measurement, we revisit one of the most widely studied anomaly free extensions of the standard model namely, gauged $L_{\mu}-L_{\tau}$ model, known to be providing a natural explanation for muon $(g-2)$. We also incorporate the presence of dark matter (DM) in this model in order to explain the recently reported electron recoil excess by the XENON1T collaboration. We show that the same neutral gauge boson responsible for generating the required muon $(g-2)$ can also mediate interactions between electron and dark matter. We consider two scenarios to explain the XENON1T excess; one with dark fermions boosted by DM annihilation and the other with inelastic down scattering of DM. In the former case, the required DM annihilation rate into dark fermion require a hybrid setup of thermal and non-thermal mechanisms to generate DM relic density. In the later case, a Dirac fermion DM, naturally stabilised due to its chosen gauge charge, is split into two pseudo-Dirac mass eigenstates due to Majorana mass term induced by singlet scalar which also takes part in generating right handed neutrino masses responsible for type I seesaw origin of light neutrino masses. The inelastic down scattering of heavier DM component can give rise to the XENON1T excess for keV scale mass splitting with lighter DM component. We fit our model with XENON1T data for both the cases and also find the final parameter space by using bounds from $(g-2)_{\mu}$, DM relic, lifetime of heavier DM, DM-electron scattering rate, neutrino trident production rate as well as other flavour physics, astrophysical and cosmological observations. The tightly constrained parameter space from all requirements remain sensitive to ongoing and near future experiments, keeping the scenario very predictive.

Speaker: Mr Satyabrata Mahapatra (INDIAN INSTITUTE OF TECHNOLOGY HYDERABAD)

Pheno21_Satyabrata.pdf

14:00 → 16:00 DM VIII

Convener: Bibhushan Shakya (CERN)

Zoom link DM VIII

14:00 Neutron stars as Pauli batteries: probing the neutron portal with internal heating of pulsars

New states that mix with the neutron, such as dark baryons and mirror neutrons, have been proposed to address dark matter, baryogenesis, the long-standing neutron lifetime anomaly, and the recent XENON1T excess. I show that such states are extensively constrained by measurements of neutron star (NS) temperatures. When Fermi-degenerate neutrons in the stellar core convert to these states via scattering and/or decay, the holes left behind in the Fermi sea are refilled by more energetic neutrons, accompanied by explosive liberation of heat. While astronomical measurements of thermal luminosities of NSs are usually motivated by the need to pinpoint cooling models, this effect provides another important incentive: directly probing the properties of the neutron. This could be achieved by imminent telescopes in the optical, ultraviolet and infrared -- i.e. by looking for NSs colder than the coldest (< 40,000 K) observed so far.

Speaker: Nirmal Raj (TRIUMF)

Raj-paulibattery-PHENO2021.pdf

14:15 Neutron star heating by inelastic dark matter

Dark matter can deposit energy in neutron stars and heat them to temperatures that could be detected by upcoming infrared telescopes like James Webb Space Telescope (JWST). These observations have a potential to complement and outperform terrestrial direct detection in a large range of dark matter masses. The difference is particulalrly striking for inelastic dark matter. Electrons are also present in neutron stars in significant proportion. Capture due to electrons can aid with the capture of leptophilc dark matter. Ultrarelativistic nature of these electrons make the calculation challenging. In this talk, I will discuss the fomulation of this capture calculation and its interesting consequences for inelastic dark matter.

Speaker: Aniket Joglekar (LAPTh, CNRS)

Pheno2021_Aniket_2.pdf

14:30 Macroscopic Dark Matter Constraints from the Red Giant Branch Helium Flash

Macroscopic dark matter candidates are large composite objects which escape standard direct detection constraints. Macros with substantial elastic scattering cross sections off visible matter can catalyze a variety of fusion processes in stars. We consider the effects of this process on Red Giant branch stars. We find that macros can ignite the helium core of these stars prematurely. We place constraints on the cross section of macroscopic dark matter with matter over the mass range $10^{17}$ g $< m <$ $10^{20}$ g.

Speaker: Zachary Johnson (University of Michigan, Ann Arbor)

14:45 Probing dark matter interactions below the neutrino floor with PopIII stars

The mere observation of the first stars (Pop III stars) in the universe can be used to place tight constraints on the strength of the interaction between dark matter and regular, baryonic matter. We apply this technique to a candidate Pop III stellar complex discovered with the HubbleSpace Telescope at z∼7 and find some of the deepest bounds to-date for both spin-dependent and spin-independent DM-nucleon interactions, over a large swath of DM particle masses. Additionally, we show that the most massive Pop III stars could be used to bypass the main limitations of direct detection experiments: the neutrino background to which they will be soon sensitive

Speaker: Cosmin Ilie (Colgate University)

DMPOPIIIPHENO21.pdf

15:00 Nuclear Fusion inside Dark Matter

Large composite states of dark fermions bound by a scalar provide a potential field under which Standard Model nuclei can accelerate to large kinetic energies, resulting in copious amounts of collisional radiation and, at the highest energies, thermonuclear fusion. In this talk, I discuss how this effect can cause white dwarfs to explode, as well as its detectability prospects at neutrino observatories like IceCube.

Speaker: Javier Fernández Acevedo (Queen's University)

PHENO2021.pdf

15:15 The 511 keV Excess and Primordial Black Holes in our Solar System

An excess of 511 keV photons has been detected from the central region of the Milky Way. It has been suggested that the positrons responsible for this signal might be produced through the Hawking evaporation of primordial black holes. After evaluating the constraints from INTEGRAL, COMPTEL, and Voyager 1, we find that black holes in mass range of ∼ (1 − 4) × 10^16 g could potentially produce this signal if they make up a small fraction of the total dark matter density. If primordial black holes are responsible for the observed 511 keV signal, then we should expect several hundred black holes to reside within the Solar System. This class of scenarios should be testable with proposed MeV-scale gamma-ray telescopes such as AMIGO or e-ASTROGAM.

Speaker: Celeste Keith (University of Chicago)

conference_presentation_511.pdf

conference_presentation_511.pptx

15:30 Probing light dark matter particles with astrphysical experiments

Strong bounds from direct detection experiment put stringent limit on the dark matter mass which forces us to go beyond WIMP model of dark matter. In recent years the light mass dark matter particles gain lots of attention among the particle physicists. In this talk I will discuss about light gauge bosons motivated from U(1) extension of standard model and axions which can be a possible dark matter candidates and its detection in several astrophysical experiments.

Speaker: Tanmay Poddar (Physical Research Laboratory)

pheno.pdf

15:45 Multiscatter Multi-component Capture of Dark Matter

In recent years the usefulness of astrophysical objects as dark matter probes has become moreand more evident, especially in view of null results from direct detection and particle production experiments. The potentially observable signatures of dark matter gravitationally trapped inside a star, or another compact astrophysical object, have been used to forecast stringent constraints on the nucleon-dark matter interaction cross section. Currently, the probes of interest are: at high red-shifts, Population III stars that form in isolation, or in small numbers, in very dense DM minihalos at z∼15−40, and, in our own Milky Way, neutron stars, white dwarfs, brown dwarfs, exoplanets, etc. Of those, only neutron stars are single component objects, and as such they are the only objects for which the common assumption made in the literature of single component capture, i.e. capture of dark matter by multiple scatterings with one single type of nucleus inside the object, is valid. In this paper, we present an extension of this formalism to multi-component objects and apply it to Pop III stars, as such, investigating the role of He on the capture rates of Pop III stars. As expected, we find that the inclusion of the heavier He nuclei will lead to an enhancement on the overall capture rates, and, as such, further improve the potential of Pop III stars as dark matter probes.

Speaker: Caleb Levy (Colgate)

Multicomponent multiscatter capture.pdf

Multicomponent multiscatter capture.pptx

14:00 → 16:00 Higgs III

Convener: Lingfeng Li (HKUST)

zoom

14:00 Studies of the CP properties of the Higgs boson at the ATLAS experiment

Studies of the CP properties of the Higgs boson in various production modes and decay channels are presented. Limits on the mixing of CP-even and CP-odd Higgs states are set by exploiting the properties of diverse final states.

Speaker: Ana Luisa Carvalho (LIP (PT))

HiggsCP_Pheno2021.pdf

14:15 Searches for new physics in Extended Higgs Sectors in CMS

Exotic decays of the Higgs boson are a well-motivated possibility, even with the discovery of a Higgs particle consistent with the SM, and they may provide the only window into BSM physics at the LHC. The Higgs boson can be used as a probe for new physics in many BSM scenarios, and this talk will cover the recent searches for exotic decays of the Higgs boson, using proton-proton collision data collected by the CMS experiment at a center-of-mass energy of 13 TeV. Higgs boson decays that are not expected in the SM, such as decays to pairs of light (pseudo) scalars, will also be covered.

Speaker: Tanvi Wamorkar (Northeastern University (US))

Pheno_Higgs_Wamorkar_26May2021.pdf

14:30 Searches for BSM Higgs bosons at ATLAS

The discovery of the Higgs boson with the mass of about 125 GeV completed the particle content predicted by the Standard Model. Even though this model is well established and consistent with many measurements, it is not capable to solely explain some observations. Many extensions addressing this shortcoming introduce additional Higgs-like bosons which can be either neutral, singly-charged or even doubly-charged. Other theories suggest that the Higgs boson may couple to hidden-sector states that do not interact under the Standard Model gauge transformations. Models predicting exotic Higgs boson decays to pseudoscalars can explain the galactic centre gamma-ray excess, if the additional pseudoscalar acts as the dark matter mediator. This talk presents recent ATLAS searches for decays of the 125 GeV Higgs boson to a pair of new light bosons, and searches for additional Higgs bosons, based on full Run 2 data of the ATLAS experiment at the LHC.

Speaker: Sanmay Ganguly (Weizmann Institute of Science (IL))

BSM_Higgs_PhenoPitt_2021.pdf

14:45 Beyond the Standard Model Effective Field Theory: The Singlet Extended Standard Model and Higgs FIts

One of the assumptions of simplified models is that there are a few new particles and interactions accessible at the LHC and all other new particles are heavy and decoupled. The effective field theory (EFT) method provides a consistent method to test this assumption. Simplified models can be augmented with higher order operators involving the new particles accessible at the LHC. Any UV completion of the simplified model will be able to match onto these beyond the Standard Model EFTs (BSM-EFT). In this paper we study the simplest simplified model: the Standard Model extended by a real gauge singlet scalar. In addition to the usual renormalizable interactions, we include dimension-5 interactions of the singlet scalar with Standard Model particles. As we will show, even when the cutoff scale is 3 TeV, these new effective interactions can drastically change the interpretation of Higgs precision measurements and scalar searches.

Speaker: Ian Lewis (The University of Kansas)

IL_Pheno21.pdf

15:00 Combined Higgs boson measurements by the ATLAS experiment and their Effective Field Theory interpretations

The most precise measurements of Higgs boson cross sections, using the framework of Simplified Template Cross Sections (STXS), are obtained from a combination of the measurements performed in the different Higgs boson decay channels. These combined measurements, as well as those from single decay channels, are used to constrain those Standard Model Effective Field Theory (SMEFT) parameters that affect the Higgs boson production and decay.

Speaker: Jiayi Chen (Brandeis University (US))

Pheno2021-final.pdf

15:15 Higgs Production in Association with a Dark-Z at Future Electron Positron Colliders

In recent years there have been many proposals for new electron-positron colliders, such as the Circular Electron-Positron Collider, the International Linear Collider, and the Future Circular Collider in electron-positron mode. Much of the motivation for these colliders is precision measurements of the Higgs boson and searches for new electroweak states. In this talk, we propose a new search for Higgs physics below the $HZ$ threshold. In particular, we propose a new light gauge boson that can be studied through pair production with the Higgs and perform a collider study to show the possibility of detecting this process in electron-positron colliders.

Speaker: Pierce Giffin (University of California, Santa Cruz)

PHENO_2021.pdf

15:30 Determination of Higgs boson properties in decays to bosons at the ATLAS experiment

With the full Run 2 pp collision dataset collected at 13 TeV, very detailed measurements of Higgs boson properties can be performed. This talk presents measurements of Higgs boson properties using decays into bosons, including production mode cross sections and simplified template cross sections, as well as their interpretations.

Speaker: Anamika Aggarwal (Nikhef National institute for subatomic physics (NL))

Pheno2021.pdf

15:45 Results and Prospects of Radiative and Electroweak Penguin Decays at Belle (II)

In the recent years, several measurements of $B$-decays with flavor changing neutral currents, i.e. $b\to s$ transitions hint at deviations from the Standard Model (SM) predictions.These decays are forbidden at tree-level in the SM and can only proceed via suppressed loop level diagrams. Rare decays of $B$ mesons are an ideal probe to search for phenomena beyond the SM, since contributions from new particles can affect the decays on the same level as SM particles.

The Belle II experiment is a substantial upgrade of the Belle detector and operates at the SuperKEKB energy-asymmetric $e^+ e^-$ collider. Early physics goals of the Belle II physics program are to rediscover these rare decays. Radiative $b\to s \gamma$ decays is already rediscovered with only a small dataset of Belle II and we are aiming to rediscover the electro-weak penguin $b\to s \ell\ell$ decays too. We will discuss about the prospects of these radiative and electroweak penguin decays with the expected $50 ab^{-1}$ dataset of Belle II.

Speaker: Soumen Halder (Tata Institute of Fundamental Research)

PHENO_SHalder.pdf

14:00 → 16:00 Neutrino II

Convener: Kevin Kelly (Fermilab)

Zoom link Neutrino II

14:00 Predictions for the Leptonic Dirac CP-Violating Phase

We explore the theoretical constraints on the observable parameters of neutrino mixing on predictions for the leptonic Dirac CP-violating phase within a class of theoretical models that include a single source of CP violation due to charged lepton corrections, with additional assumptions made regarding specific ansatzes for the probability distributions of the continuous input parameters. We consider two scenarios: one in which the model parameters have independent distributions, and another in which the model parameters have conditional probability distributions that can generally better reproduce the observable mixing angle distributions. In both cases we can guarantee a physically meaningful prediction for the most likely range of values for the leptonic Dirac CP-violating phase.

Speaker: Alexander Stuart (Universidad de Colima)

Pheno2021_Stuart.pdf

14:15 Neutrino masses from simple scoto-seesaw model with spontaneous CP violation

I will discuss our recent work on a simple scoto-seesaw model that accounts for dark matter and neutrino masses with spontaneous CP violation. This is achieved with a single horizontal $\mathcal{Z}_8$ discrete symmetry, broken to a residual $\mathcal{Z}_2$ subgroup responsible for stabilizing dark matter. CP is broken spontaneously via the complex vacuum expectation value of a scalar singlet, inducing leptonic CP-violating effects. We find that the imposed $\mathcal{Z}_8$ symmetry pushes the values of the Dirac CP phase and the lightest neutrino mass to ranges already probed by ongoing experiments.

Speaker: D. Barreiros (CFTP/IST, U.Lisboa)

Barreiros_PHENO2021.pdf

14:30 Leptogenesis from $SU(5)$ GUT with $\mathcal{T}_{13}$ Family Symmetry

We investigate both resonant and non-resonant thermal leptogenesis in the context of the recently proposed ``asymmetric texture'' from $SU(5)$ GUT with $\mathcal{T}_{13}$ family symmetry. A single source of $CP$ violation, originating from the vacuum alignment of the seesaw familons resulting in a complex tribimaximal mixing, is shown to yield Dirac $CP$ violation in agreement with global fits, and successfully explains baryon asymmetry via leptogenesis. For the non-resonant case, the sign of the baryon asymmetry fixes the previously unresolved sign of the TBM phase. In the resonant scenario, right-handed neutrino masses can be as low as $\mathcal{O} (\text{GeV})$ and is within the sensitivity of experiments (e.g. SHiP, DUNE) searching for heavy neutral leptons.

Speaker: Moinul Hossain Rahat (University of Florida)

Pheno2021_Rahat.pdf

14:45 A scotogenic model for realistic neutrino mixing with S3 symmetry

[This is based on Phys.Rev. D100 (2019) no.3, 035009 by Soumita Pramanick]

In this model, realistic neutrino mixing is obtained radiatively using $S_3 \times Z_2$
symmetry at one-loop level. The two right-handed neutrinos present in the model when maximally mixed
can yield the structure of the left-handed Majorana neutrino mass matrix corresponding to
$\theta_{13}=0$, $\theta_{23}=\pi/4$ and any value of $\theta_{12}^0$ specific to the Tribimaximal (TBM), Bimaximal (BM) and Golden Ratio (GR) or some other mixings.
Non-zero $\theta_{13}$, deviation of $\theta_{23}$ from $\pi/4$ and
small corrections to the solar mixing angle $\theta_{12}$ can be achieved in a single stroke by shifting from this maximal mixing in the right-handed neutrino sector by a small amount.
In this scotogenic model where non-zero $\theta_{13}$ was obtained by deviating from maximal mixing in the right-handed neutrino sector, two $Z_2$ odd inert $SU(2)_L$ doublet scalars were also present, the lightest of which can be a dark matter candidate.

Speaker: Soumita Pramanick (National Centre for Nuclear Research (NCBJ), Warsaw, Poland)

Pheno2021_SoumitaPramanick.pdf

15:00 Study of tau neutrino production with nuclear emulsion at CERN-SPS

The data on tau neutrino is very scarce, only a few experiments have detected its interactions. At FNAL beam dump experiment DONUT, tau neutrino interaction cross-section was directly measured with a large systematical (~50%) and statistical (~30%) errors. The main source of systematical error is due to a poor knowledge of the tau neutrino flux. The effective way for tau neutrino production is the decay of Ds mesons, produced in proton-nucleus interactions. The DsTau experiment at CERN-SPS has been proposed to measure an inclusive differential cross-section of a Ds production with a consecutive decay to tau lepton in p-A interactions. The goal of experiment is to reduce the systematic uncertainty to 10% level. A precise measurement of the tau neutrino cross section would enable a search for new physics effects such as testing the Lepton Universality (LU) of Standard Model in neutrino interactions. The detector is based on nuclear emulsion providing a sub-micron spatial resolution for the detection of short length and small “kink” decays. Therefore, it is very suitable to search for peculiar decay topologies (“double kink”) of Ds→τ →X. After successful pilot runs and data analysis, CERN had approved the DsTau project as a new experiment NA65 in 2019. During the physics runs, 2.3×10^8 proton interactions will be collected in the tungsten target, and about 1000 Ds→τ decays will be detected. In this talk, the results from the pilot run will be presented and the prospect for physics runs in 2021-2022 will be given.

Speaker: Osamu Sato (Nagoya University (JP))

DsTau-Sato.pdf

15:15 Quasi-Dirac neutrinos and the Baryon Asymmetry of the Universe

Though two of the biggest puzzles in fundamental physics--the cosmic baryon asymmetry and tiny neutrino masses--can be elegantly accommodated in leptogenesis models, usually, these models cannot be subject to direct tests due to additional high energy parameters which are decoupled from low energy phenomena. In our novel scenario, the light neutrino masses are obtained through a quasi-Dirac seesaw mechanism, where B-L is slightly broken at high scale. The same source of breaking is responsible for successful leptogenesis close to weak scale as well as the small mass splitting between the quasi-Dirac light neutrinos. Nontrivially, the viable parameter space for leptogenesis spans over the one which can be explored in the neutrino oscillation experiments.

Speaker: Dr Alberto Tonero (Carleton University)

slides.pdf

15:30 Exploring neutrino long-range interactions in the cosmos

Cosmology is well suited to study the effects of long range interactions due to the large densities in the early Universe. In this talk, I will explore how the energy density and equation of state of cosmological neutrinos diverge from the commonly assumed ideal gas form under the presence of scalar long range interactions with a range much smaller than cosmological scales. In this scenario, "small"-scale physics can impact our largest-scale observations.
Performing an analysis to present and future cosmological data, I will show that the current cosmological neutrino mass bound is fully avoided in the presence of a long range interaction. This opens the possibility for a laboratory neutrino mass detection in the near future. I will also demonstrate an interesting complementarity between neutrino laboratory experiments and the future EUCLID survey.

Speaker: Ivan Esteban (CCAPP, Ohio State University)

Talk.pdf

15:45 Transient Sources and the light curves of BSM-induced neutrino echoes in the optically thin limit

High-energy cosmic neutrinos present a unique opportunity to search for physics beyond Standard Model thanks to their reach to the highest energies and longest baseline. Beyond Standard Model induced interactions of high-energy neutrinos during their propagation yield distinct signatures in their observables in neutrino telescopes. Energy, flavor, arrival direction, and the arrival time of neutrinos can be modified when new physics is present. In the meantime, the success of time-domain multimessenger astrophysics in identifying the first evidence for the sources of high-energy cosmic neutrinos has demonstrated the feasibility of exploring new physics with transient sources of cosmic neutrinos. New physics scenarios will induce a time delay in the observation of high-energy neutrinos from astrophysical transients. The presence or absence of a delay in the arrival time of high-energy neutrinos compared to other cosmic messengers will provide a powerful probe of new physics in the neutrino sector. In this talk, we present the light curves for neutrino emission from transients for different new physics scenarios assuming an optically thin limit and discuss the expected temporal distribution for the arrival time high-energy neutrinos in each scenario. We further discuss the implications for current and future neutrino detectors.

Speaker: Ali Kheirandish (Pennsylvania State University)

pheno21_ak.pdf

14:00 → 16:00 QCD & EW I

https://pitt.zoom.us/j/98017239907

Convener: Sida Lu (University of Wisconsin-Madison)

zoom

14:00 Analytic continuations of two loop four point master integrals for amplitudes with vector boson final states

We will discuss some analytic continuations to known two loop diboson master integrals which are phenomenologically relevant and use them to evaluate two loop helicity amplitudes for processes with vector boson final states.

Speaker: Sushruth Muralidharan (University at Buffalo)

presentation.pdf

14:15 NNLO single-top-quark production and decay: Discrepancies resolved, PDFs challenged

We present our recent NNLO calculation of t-channel single-top-quark production and decay that resolves a disagreement between two previous calculations whose size at the inclusive level was comparable to the NNLO correction itself, and was even larger differentially. Moving beyond those comparisons, we have included b-quark tagging to allow for comparison with experiment, and added the ability to use double deep inelastic scattering (DDIS) scales ($\mu^2=Q^2$ for the light-quark line and $\mu^2=Q^2+m_t^2$ for the heavy-quark line) that allow for direct testing of parton distribution function (PDF) stability. All code will be publicly available in MCFM.

We demonstrate that several characteristic fiducial and differential standard model observables, and observables sensitive to new physics, are stable between NLO and NNLO, but point out there is a sizable difference in the prediction of some exclusive $t+n$-jet cross sections. Finally, we use this calculation to present preliminary results which indicate that some commonly used PDF sets are in significant disagreement, both with each other and with themselves between perturbative orders when evaluated at Tevatron energies.

Speaker: Zack Sullivan (Illinois Institute of Technology)

ZS_PHENO21.pdf

14:30 NLO corrections to $W^{+}Z\gamma$ production in SM and tree-level effects of dimension-eight operators in SMEFT at the LHC

Triple gauge boson production is an important class of processes at the LHC. It allows measurements to test the quartic gauge couplings in the Standard Model and draw the limits of non-standard gauge couplings in the framework of Standard Model effective field theory (SMEFT). We perform the computations of the NLO EW and QCD corrections to $W^{+}Z\gamma$ production with leptonic decays in SM at the LHC. All the non-resonance and interference contribitions are included, namely, $p\;p\rightarrow e^{+}\;\nu_{e}\;\mu^{+}\;\mu^{-}\;\gamma$. We study the impact of the corrections on the total and differential cross sections. We also study the tree-level effects of dimension eight operators in SMEFT. The selected operators are turned on individually and the corresponding unitarity bounds are derived based on partial wave expansions. By showing the interplay between the NLO corrections in SM and the effects of dimension-eight operators in SMEFT, we conclude that the NLO EW corrections are indispensable to test the gauge couplings in SM and set the constraints on the dimension-eight operators in SMEFT precisely.

Speaker: Huanfeng Cheng (SUNY Buffalo)

pheno21_WZA_huanfeng.pdf

14:45 Multiboson measurements at CMS

Measurements of processes involving multiboson final states constitute a precision test of the Standard Model. Moreover, discrepancies between theoretical predictions and experimental measurements could hint to new physics through the presence of anomalous gauge couplings. These processes are also dominant backgrounds for Higgs boson measurements, and searches for new particles with diboson final states. The most relevant CMS measurements at 13 TeV will be presented.

Speaker: Shilpi Jain (University of Minnesota (US))

multiboson_SJ_v1.pdf

15:00 Mixed EW-QCD three-loop leading fermionic corrections to electroweak precision observables

Measurements of electroweak precision observables at future electron-position colliders, such as the CEPC, FCC-ee, and ILC, will be sensitive to physics at multi-TeV scales. To achieve this sensitivity, precise predictions for the Standard Model expectations of these observables are needed, including corrections at the three- and four-loop level. In this article, results are presented for the calculation of a subset of three-loop mixed electroweak-QCD corrections, stemming from diagrams with a gluon exchange and two closed fermion loops. The numerical impact of these corrections is illustrated for a number of applications: the prediction of the W-boson mass from the Fermi constant, the effective weak mixing angle, and the partial and total widths of the Z boson. Two alternative renormalization schemes for the top-quark mass are considered, on-shell and MSbar

.

Speaker: Lisong Chen

Leading Fermionic Three-Loop Corrections to EWPOs (1).pdf

15:15 CuTe-MCFM: Fiducial $q_T$ resummation for color-singlet processes at N$^3$LL+NNLO

We present a framework for $q_T$​ resummation at N$^3$LL+NNLO accuracy for arbitrary color-singlet processes based on a factorization theorem in SCET. Our implementation CuTe-MCFM is fully differential in the Born kinematics and matches to large-$q_T$​ fixed-order predictions at relative order $\alpha_s^2$​. It provides an efficient way to estimate uncertainties from fixed-order truncation, resummation, and parton distribution functions. In addition to W$^\pm$, Z and H production, also the diboson processes γγ, Zγ, ZH and W$^\pm$H are available, including decays. We discuss and exemplify the framework with direct comparisons to experimental measurements as well as inclusive benchmark results.

Speaker: Tobias Neumann (Brookhaven National Laboratory)

Neumann_Tobias_Pheno2021.pdf

15:30 Two-loop QCD corrections to Wbb production at hadron colliders

I will present an analytic computation of the two-loop QCD corrections to ud->Wbb for an on-shell W-boson using the leading colour and massless bottom quark approximations. We perform an integration-by-parts reduction of the unpolarised squared matrix element using finite field reconstruction techniques and identify an independent basis of special functions that allows an analytic subtraction of the infrared and ultraviolet poles.

Speaker: Heribertus Bayu Hartanto (Cambridge University)

Bayu_PHENO2021.pdf

15:45 Electroweak Restoration at the LHC and Beyond

The LHC is exploring electroweak (EW) physics at the scale EW symmetry is broken. As the LHC and new high energy colliders push our understanding of the Standard Model to ever-higher energies, it will be possible to probe not only the breaking of but also the restoration of EW symmetry. We propose to observe EW restoration in double EW boson production via the convergence of the Goldstone boson equivalence theorem. We measure this convergence through the ratio of differential cross sections for VH production. We present a method to extract this ratio from collider data. With a full signal and background analysis, we demonstrate that the 14 TeV HL-LHC can confirm that this ratio converges to one to 40% precision while at the 27 TeV HE-LHC the precision will be 6%. We also investigate statistical tests to quantify the convergence at high energies. Our analysis provides a roadmap for how to stress test the Goldstone boson equivalence theorem and our understanding of spontaneously broken symmetries, in addition to confirming the restoration of EW symmetry.

Speaker: Samuel Lane (University of Kansas)

ParallelTalk-Samuel-Lane.pdf

16:00 → 16:30 Coffee Break

16:30 → 18:45 BSM VI

Convener: Brian Shuve (Harvey Mudd College)

zoom

16:30 Minimal SU(5) Unification

A minimal model of $SU(5)$ Grand Unification is proposed. The model is entirely built out of the first five lowest dimensional $SU(5)$ representations. Charged and neutral fermion mass generation mechanisms are non-trivially linked together. The main predictions of the model are that $(i)$ the neutrinos are Majorana particles, $(ii)$ one neutrino is massless, $(iii)$ the neutrinos have normal mass ordering, and $(iv)$ there are four new scalar multiplets at or below a $120$\,TeV mass scale. An improvement of the current $p \rightarrow \pi^0 e^+$ lifetime limit by a factor of $2$, $15$, and $96$ would require these four scalar multiplets to reside at or below the $100$ TeV, $10$ TeV, and $1$ TeV mass scales, respectively.

Speaker: shaikh saad (oklahoma state university)

saad.pdf

16:45 Characterising Different Beyond the Standard Model Signatures at Present and Future Colliders

Several theories Beyond the Standard Model (BSM) have been proposed so far to address the shortcomings of the Standard Model. Such theories predict various resonances with different spins. In a 2 → 2 pair-production, spins of the scattered states determine the nature of differential angular distribution of the scattered pair in the rest frame of interaction. However, the Large Hadron
Collider (LHC) being a hadronic machine, the rest frame of the interacting partons is unknown, and hence, the angular distributions of the scattered states at the rest frame needs to be evaluated from the final states. We showed how longitudinal boost can be estimated from the final states, which then can be instrumental in identifying the spins of such BSM particles at LHC[1]. In similar context we also explored the electron-photon[2] and electron-hadron[3] colliders in probing Leptoquarks by means of zeros in the cross-section in their angular distributions. We showed that these two colliders are complementary to each other in probing all the leptoquark models and identifying their gauge representation. Finally we show how displaced Higgs vertex could be a probe for Type-III Seesaw Model[4].

References
[1] P. Bandyopadhyay, S. Dutta, M. Jakkapu and A. Karan, [arXiv:2007.12997 [hep-ph]].
[2] P. Bandyopadhyay, S. Dutta and A. Karan, Eur. Phys. J. C 80 (2020) no.6, 573
[3] P. Bandyopadhyay, S. Dutta and A. Karan, [arXiv:2012.13644 [hep-ph]].
[4] P. Bandyopadhyay, S. Dutta, C. Sen and Aleesha K. T, “Type-III Seesaw Probes from Displaced Higgs Production at LHC and MATHUSLA,” (under preparation).

Speaker: Saunak Dutta (Indian Institute of Technology Hyderabad)

Saunak_Pheno2021.pdf

17:00 Probing UV-completion via Gravitational Waves: Pecei-Quinn Phase Transition

Attempts to solve naturalness by having the weak scale as the only breaking of classical scale invariance in 4-dimensional Quantum Field Theories satisfy Total Asymptotic Freedom (TAF): the theory holds up to infinite energy, where all coupling constants flow to zero and is devoid of any Landau poles. Specifically we will discuss a fundamental field theory of the QCD axion in the totally asymptotically free (TAF) scenario, and the dynamics of the Peccei-Quinn (PQ) phase transition there-in. The PQ phase transition can be of strongly first order and produce stochastic gravitational waves (GW) background within the reach of GW detectors, with predictions in a frequency peak in the range
100-1000 Hz with an amplitude that is already within the sensitivity of LIGO \& advanced LIGO.

Speaker: Anish Ghoshal (L)

17:15 Detecting new forces in the gravitational wave background

Supermassive black hole binaries generate a gravitational wave background that will soon be measured by pulsar timing arrays. While the amplitude of this background is uncertain, the shape of its spectrum is a robust prediction of general relativity. We show that the effects of new forces beyond the Standard Model can modify this prediction and introduce unique features into the spectral shape. As a benchmark scenario, we study the case in which the black holes themselves are charged under a new long-range force, which occurs naturally in many dark sector models. In this situation, we find that pulsar timing arrays can detect the effects of such a force on the spectral shape even if typical charges are small, making the shape a powerful new probe of fundamental physics.

Speaker: Benjamin Lehmann (UC Santa Cruz)

lehmann_slides.pdf

17:30 Viable Full Unification of the Standard Model into $E_8$

A 10 dimensional model with $\mathcal{N}=1$ SUSY and $E_8$ as a gauge group will be presented. It will be shown that through the orbifold $T^6/(Z_3 \times Z_3)$, only the Standard Model remains after compactification, with feasible Yukawa couplings. Gauge coupling unification can be achieved at $M_{GUT}=10^7 GeV$ with a viable proton lifetime. Therefore the highly predictive extra dimensional GUT model can be within reach of near future experiments.

Speaker: Francisco J. de Anda N.

E8Pheno.pdf

17:45 Parity Solutions to the Strong CP Problem

Parity solutions to the strong CP problem are a compelling alternative to approaches based on Peccei-Quinn symmetry, particularly given the expected violation of global symmetries in a theory of quantum gravity. The most natural of these solutions break parity at a low scale, giving rise to a host of experimentally accessible signals. In this talk, we give an overview of this class of solutions and assess the simplest parity-based solution in light of LHC and flavor constraints. We further highlight prospects for near-future tests at colliders, tabletop experiments, and gravitational wave observatories. The origin of parity breaking and associated gravitational effects provide new avenues for discovery through EDMs and gravity waves, establishing generalized parity as a promising and testable solution to the strong CP problem.

Speaker: Amara McCune (University of California, Santa Barbara)

Pheno 2021.pdf

18:00 Positivity in Multi-Field EFTs

This talk discuss the general method for obtaining full positivity bounds on multi-field effective filed theories (EFTs), from analyticity and unitarity requirements on the UV theory. We then identify the allowed parameter space as the dual to a spectrahedron, constructed from crossing symmetries of the amplitude, and show that finding the optimal bounds for a given number of modes is equivalent to a geometric problem: finding the extremal rays of a spectrahedron, we show how this is done analytically for simple cases, and numerically formulated as semidefinite programming (SDP) problems for more complicated cases. We demonstrate this approach with a number of well-motivated examples in particle physics and cosmology, including EFTs of scalars, vectors, fermions and gravitons.

Speaker: Xu Li (Institute of higt energy physics)

positivity_XuLi_PHENO.pdf

18:15 TeV-scale Lepton Number Violation: 0νββ−decay, the origin of matter and energy frontier probes

Lepton number violation (LNV) is a very attractive research topic for theoretical and experimental physicists due to its implications beyond the Standard Model. It provides feasible theoretical explanations to several open questions in particle physics (e.g., the origin of neutrino mass) and also has a rich phenomenology at different energy scales. We explore the underlying connections between neutrinoless double 𝛽−decay (0𝜈𝛽𝛽) experiments, hadron colliders, and cosmology observations. In the context of simplified models, we show that future collider and 0𝜈𝛽𝛽 experimental results may complement each other.

Speaker: Sebastian Urrutia-Quiroga (University of Massachusetts Amherst)

Pheno2021_suq_lnv.pdf

18:30 Searches for SUSY in hadronic final states with the CMS experiment

Searches for SUSY in hadronic final states with the CMS experiment

Speaker: Mr Uttiya Sarkar (CNRS/IN2P3/LLR-Polytechnique (FR))

Pheno2021_UttiyaSarkar_v2.pdf

16:30 → 18:45 DM IX

Convener: Joshua Berger (Colorado State University)

Zoom link DM IX

16:30 The Primordial Black Holes Variations

In the age of gravitational wave astronomy, the possibility that some of the black holes in the universe have a primordial, rather than stellar, origin, and that they might be a non-negligible fraction of the cosmological dark matter, is quite intriguing. I will review the status of the field, and comment on search strategies and future prospects for detection across many decades in black hole mass. I will also discuss how light primordial black holes could seed both baryonic and particle dark matter in the very early universe.

Speaker: Stefano Profumo (University of California, Santa Cruz)

Profumo_Pheno2021_210526.pdf

16:45 Radiofrequency Dark Photon Dark Matter across the Sun

Dark photon as an ultralight dark matter candidate can interact with the Standard Model particles via kinetic mixing. We propose to search for the ultralight dark photon dark matter using radio telescopes with solar observations. The dark photon dark matter can efficiently convert into photons in the outermost region of the solar atmosphere, the solar corona, where the plasma mass of photons is close to the dark photon rest mass. Due to the strong resonant conversion and benefiting from the short distance between the Sun and the Earth, the radio telescopes can lead the dark photon search sensitivity in the mass range of $4 \times 10^{-8} - 4\times 10^{-6} \, \rm{eV}$, corresponding to the frequency $10 - 1000 \, {\rm MHz}$. As a promising example, the operating radio telescope LOFAR can reach the kinetic mixing $\epsilon \sim 10^{-13}$ ($10^{-14}$) within 1 (100) hour solar observations.The future experiment SKA phase 1 can reach $\epsilon \sim 10^{-16} - 10^{-14}$ with $1$ hour solar observations.

Speaker: Jia Liu (Peking University)

pheno-2021-JL-v1.pdf

17:00 Visible Dark Photon Flashes from Neutron Star Mergers

In this talk I discuss how dark photons can produce bright observable flashes during binary neutron star mergers (BNS). Dark photons are a new massive vector field that kinetically mixes with the photon, and through this mixing interacts with charged standard model matter. It provides one of the three renormalizable portals between the Standard Model (SM) and dark sectors, which are by definition not charged under the standard model gauge group. The hot, dense conditions immediately after a BNS can produce a large flux of dark photons which escape the merger and decay to standard model particles, producing a bright, isotropic gamma-ray signal.

Speaker: Melissa Diamond (Johns Hopkins)

Diamond_pheno_presentation.pdf

Diamond_pheno_presentation.pptx

17:15 The causal structure of superfluid dark matter

There has been much interest in novel models of dark matter that exhibit interesting behavior on galactic scales. A primary motivation is the observed Baryonic Tully-Fisher Relation in which the mass of galaxies increases as the quartic power of rotation speed. This scaling is not obviously accounted for by standard cold dark matter. This has prompted the development of dark matter models that exhibit some form of MONDian phenomenology to account for this galactic scaling, while also recovering the success of cold dark matter on large scales. A beautiful example of this are the so-called superfluid dark matter models, in which a complex bosonic field undergoes spontaneous symmetry breaking on galactic scales, entering a superfluid phase with a 3/2 kinetic scaling in the low energy effective theory, that mediates a long-ranged MONDian force. In this work we examine the causality and locality properties of these and other related models.

Speaker: Mark Hertzberg (Tufts University)

HertzbergPheno2021.05.26.pdf

17:30 Sterile Neutrino Dark Matter via Secret Neutrino Interactions

I will present the anatomy of production mechanisms for sterile neutrino dark matter in the presence of new interactions among either active or sterile neutrinos. These new interactions can be mediated by a scalar or a vector, and allow sterile neutrinos to make up all the dark matter while safely evading all current experimental bounds. We identify three regimes of the mediator’s mass and coupling where it makes a distinct impact on dark matter production through the dispersion relations and/or scattering rates. These models serve as a well-motivated target for the upcoming experimental searches.

Speaker: Walter Tangarife (Loyola University Chicago)

Tangarife_SterileNeutrino_Pheno21.pdf

17:45 keV sterile neutrino dark matter enabled by a dark photon

A keV sterile neutrino ($\nu_s$) that mixes with active neutrinos ($\nu_a$) is a well-motivated warm dark matter candidate with rich cosmological and astrophysical implications. The production of such a particle in the early Universe typically relies on the existence of a large lepton asymmetry in the primordial plasma, which can however spoil the successful predictions of Big Bang Nucleosynthesis. In this talk, I present an alternative scenario in which active neutrinos couple to an oscillating condensate of a very light $L_\mu-L_\tau$ gauge field, which enables resonant $\nu_a-\nu_s$ oscillations in the early Universe. The resulting sterile neutrino abundance is consistent with the observed dark matter one while respecting X-ray constraints on $\nu_s\rightarrow\nu_a\,\gamma$ decays. As a side effect, potentially observable deviations in (atmospheric) neutrino oscillations can persist to the present.

Speaker: Gonzalo Alonso-Álvarez (McGill University)

210526_Pheno2021_Gonzalo_Alonso_Alvarez.pdf

18:00 Thermal Squeezeout of Dark Matter

I present a detailed study of the confinement phase transition in a dark sector with a SU(N) gauge group and a single generation of dark heavy quark. I focus on heavy enough quarks such that their abundance freezes out before the phase transition and the phase transition is of first-order. I show that during this phase transition the quarks are trapped inside contracting pockets of the deconfined phase and are compressed enough to interact at a significant rate, giving rise to a second stage of annihilation that can dramatically change the resulting dark matter abundance. As a result, the dark matter can be heavier than the often-quoted unitarity bound of ~100 TeV. These findings are almost completely independent of the details of the portal between the dark sector and the Standard Model.

Speaker: Pouya Asadi (Massachusetts Institute of Technology)

PHENO21_May_2021_DM.pdf

18:15 Glueball dark matter in SU(N) lattice gauge theory

The glueballs in the SU(N) Yang-Mills theory are theoretically the most natural among composite dark matter scenarios. In this work, we evaluate the interglueball potential in SU(N) lattice gauge theories using the HALQCD method and derive the glueball dark matter scattering cross section, and then constrain the scale parameter of the gauge theory from the observational data.

Speaker: Nodoka Yamanaka (Kennesaw State University)

2021.05.26_yamanaka.pdf

18:30 Search for BSM Higgses at the HL-LHC

We search specifically for the heavy resonant scalars (H/A) decaying via $H\to hh$, $H\to t\bar{t}$ and $(b\bar{b})H\to \tau\tau$ final states, at the HL-LHC. After performing multivariate analysis using the BDT algorithm in various final states, we set upper limits on the production cross-section of a heavy scalar times its branching ratio into final state products for different heavy scalar masses values. Finally, we translate these limits and put strong constraints on the $m_A-tan\beta$ parameter space in the context of Minimal Supersymmetric Standard Model (MSSM). We further explore the supersymmetric (susy) final states coming from MSSM Higgs decaying via neutralinos and charginos, collectively called electroweakinos. They give rise to mono-(h/Z) + missing energy final states. We consider backgrounds coming from Standard Model (SM) and susy processes. The susy backgrounds have not been considered in this kind of analysis earlier, which comes from direct electroweakino production via SM mediators. The case of wino-like long-lived chargino decaying from MSSM Higgs is also discussed. They improve the sensitivity in disappearing charged track searches at the LHC because of the boost received from heavy Higgs bosons.

Speaker: Mr Amit Adhikary (Indian Institute of Science)

Pheno2021_AmitAdhikary.pdf

16:30 → 18:30 DM VI

Convener: Juri Smirnov (Ohio State University, CCAPP)

Zoom link DM VI

16:30 Cancellation in Dark Matter-Nucleon Interactions: the Role of Non-Standard-Model-like Yukawa Couplings

Extensive searches to probe the particle nature of dark matter (DM) have been going on for some decades now but, so far, no conclusive evidence has been found. Among various options, the Weakly Interacting Massive Particles (WIMP) remains one of the prime
possibilities as candidates for DM near the TeV scale. Taking a phenomenological view, such null results may be explained for a generic WIMP in a Higgs-portal scenario if we allow the light-quark Yukawa couplings to assume non-Standard Model (non-SM)-like values. This follows from a cancellation among different terms in the DM-nucleon scattering which can, in turn, lead to a vanishingly small direct-detection cross section. It might also lead to isospin violation in the DM-nucleon scattering. Such non-SM values of light-quark Yukawa couplings may be probed in the high luminosity run of the LHC.

Speaker: Mr Bibhabasu De (IOP Bhubaneswar)

Pheno_2021_Bibhabasu_De.pdf

16:45 Closing the window for WIMPy inelastic dark matter with heavy nuclei

The kinematics of WIMP dark matter-nuclear scattering is drastically altered if the interaction is inelastic, i.e. dark matter is up-scattered to a heavier state with certain mass splitting. With $\mathcal{O}$(100) keV mass splitting inelastic dark matter will evade the search in most direct detection experiments, where the momentum transfer is limited either by the mass of target nuclei, or by the detector response. We propose a novel way to search for inelastic dark matter with heavy elements. In such experiments, through inelastic scattering on target nuclei dark matter can yield a signal either via nuclear recoil or nuclear excitation. We illustrate this method using results from low-energy gamma quanta searches in low-background experiments with Hf and Os metal samples, and measurements with CaWO$_4$ and PbWO$_4$ crystals as scintillating bolometers. We place novel bounds on WIMPy inelastic dark matter up to the mass splitting of about 640~keV, and provide forecasts for the reach of future experiments.

Speaker: Ningqiang Song (Queen's University)

IDM_pheno2021_Song.pdf

17:00 Improved Calculation of Dark Matter-Electron Scattering in Semiconductors

Semiconducting targets (such as Silicon and Germanium) are exceptionally sensitive detectors of sub-GeV Dark Matter (DM). An incident DM particle can scatter off the target electrons and excite them across the band gap. The scattering rate therefore crucially depends on the wave functions, and energies, of the target electrons. Usually the electronic states near the band gap are computed with density functional theory (DFT). We extend this calculation in two ways: including more electronic states above, and below, those computed with DFT with semi-analytic expressions, and incorporate all-electron reconstruction effects which have been previously overlooked. We will discuss for what targets and DM models these effects will be important for, and highlight the cases where the results significantly change the detection prospects in ongoing experiments such as SuperCDMS and DAMIC.

Speaker: Tanner Trickle (California Institute of Technology)

05_26_21_PHENO_EXDM.pdf

17:15 Implications on new physics from neutrino non-standard interactions in the EFT framework

The absence of any definite signals of new physics at colliders and from precision measurements has gradually changed our method in searching for new physics: from specific UV models to model-independent studies in the EFT framework. In light of the rich data from current and near-future reactor and long-baseline neutrino oscillation experiments, as well as the precision measurements of Neff from Planck and CMB-S4, in this talk, I will present our recent work on neutrino non-standard interactions and also discuss their implications on the UV physics in a model-independent approach.

Speaker: Yong Du (ITP CAS)

PEHNO2021-YongDu.pdf

17:30 Twin Higgs Portal Dark Matter

Many minimal models of dark matter (DM) or canonical solutions to the hierarchy problem are either excluded or severely constrained by LHC and direct detection null results. In particular, Higgs Portal Dark Matter (HPDM) features a singlet scalar minimally coupled to the Higgs, and because the same coupling mediates both thermal freeze out and direct detection the measured dark matter relic abundance leads to definite predictions for direct detection experiments that are now almost entirely excluded. The Twin Higgs solves the little hierarchy problem without coloured top partners by introducing a twin sector related to the Standard Model by a discrete symmetry. In this talk we generalize HPDM to arbitrary Twin Higgs models and introduce Twin Higgs Portal Dark Matter (THPDM), which features a scalar dark matter candidate with an $SU(4)$-invariant quartic coupling to the Twin Higgs scalar sector. Loop corrections motivate the DM mass to be near the Twin Higgs scale, which means DM annihilation proceeds through the unsuppressed Twin Higgs portal coupling while direct detection is suppressed by the pNGB nature of the 125 GeV Higgs. For a standard cosmological history, this mismatch results in a predicted direct detection signal for THPDM that is orders of magnitude below the HPDM prediction with very little dependence on the precise details of the twin sector. Many Twin Higgs models additionally feature asymmetric reheating mechanisms in order to suppress unobserved twin radiation contributions to $\Delta N_{\text{eff}}$. These mechanisms dilute the DM relic abundance, further reducing the expected direct detection signatures to near or below the neutrino floor.

Speaker: Shayne Gryba (University of Toronto)

Pheno2021_ShayneGryba.pdf

17:45 Galactic Acceleration from Pulsar Timing

Determining the distribution of dark matter in the Milky Way Galaxy is crucial to grounding searches for the particles comprising dark matter. Measurements of the galactic dark matter content currently rely on equilibrium assumptions to infer the forces acting upon stars from the distribution of observed velocities. Millisecond pulsars, with temporal stability rivaling even some terrestrial atomic clocks at long timescales, can be used as an ensemble of accelerometers in the galactic neighborhood. From these pulsars we can directly extract the local galactic acceleration. We present two methods of extracting the galactic acceleration. First, from pulsar spin period measurements, we demonstrate acceleration sensitivity with about 1$\sigma$ precision using 117 pulsars. In a second method, we analyze the orbital periods of 13 binary pulsar systems that eliminates systematics associated with pulsar braking and results in a local acceleration of $\left(1.7\pm0.5\right)\times{10}^{-10}\mathrm{ m/s}^2$ in good agreement with expectations. This work is a first step toward dynamically measuring acceleration gradients that will eventually inform us about the dark matter density distribution in the Milky Way Galaxy.

Speaker: Reza Ebadi (University of Maryland College Park)

18:00 ATLAS results on charmonium and B_c and exotic heavy hadrons

Recent results from the proton-proton collision data taken by the ATLAS experiment on the charmonium production and B_c production and exotic heavy hadrons will be presented. The measurement of J/psi and psi(2S) differential cross sections at large transverse momentum values will be reported as measured on the whole Run 2 dataset at 13 TeV centre-of-mass energy. The measurement of the differential ratios of the B_c+ and B+ production cross sections at 8 TeV will be reported. Studies of the pentaquarks with hidden charm in the Lambda_b decays in proton-proton collisions at 7 - 8 TeV will also be discussed.

Speaker: Leonid Gladilin (M.V. Lomonosov Moscow State University (RU))

gladilin_talk.pdf

18:15 Search for rare electroweak decay B+→K+νν in early Belle II dataset

An analysis of the B+→K+νν decay mode using 63~fb−1 of Υ(4S) data collected during the 2019 and 2020ab run by the Belle II experiment is reported. A new inclusive tagging method is used to enhance sensitivity to this rare process. The method is validated with dedicated samples including 9.2 fb−1 of data taken off resonance.

Speaker: Cyrille Praz (Deutsches Elektronen-Synchrotron DESY)

pheno2021_b2knn_v5.pdf

16:30 → 18:45 Higgs IV

Convener: Dorival Goncalves (Oklahoma State University)

zoom

16:30 A suppressed Higgs coupling in a classically confromal extension of the standard model

We consider a classically conformal $U(1)$ extension of the Standard Model (SM). The $U(1)$ symmetry is radiatively broken by the Coleman-Weinberg mechanism, after which the $U(1)$ Higgs field $\phi$ drives electroweak symmetry breaking through a mixed quartic coupling with the SM Higgs doublet with coupling constant $\lambda_{mix}$. We calculate the Higgs triple couplings in this system and find a suppression of the coupling $g_{h \phi \phi}$ when compared to the naively expected value $g_{h \phi \phi} \sim \lambda_{mix} v_{h}$ ($v_{h} = 246$ GeV), likely due to the unique nature of the classically conformal potential. The suppression opens up parameter space for the mixing angle $\theta$ between SM Higgs and $U(1)$ Higgs eigenstates. We consider experimental signals for such conformal structure via the anomalous Higgs decay $h \rightarrow \phi \phi$ and anomalous SM Higgs couplings. The conformal structure would allow for a sizeable anomalous SM Higgs coupling alongside a heavily suppressed $h \rightarrow \phi \phi$ decay mode.

Speaker: Victor Baules (University of Alabama, The)

VBaules_suppressed_coupling.pdf

16:45 Higgs Mechanism from On-Shell Massive Amplitude

Recently an on-shell formalism of scattering amplitudes for all masses and spins have been developed by Nima, Tzu-Chen and Yu-tin. In particular, Higgs mechanism can be understood as IR unification of different UV massless helicity amplitudes. This is complementary to the classic results by Cornwall et al, who have proved that the only consistent UV theory of interacting massive scalar, spinor and vector fields is equivalent to the spontaneously broken gauge theory. In this talk, I will talk about how the elegant on-shell massive formalism can help to understand the Higgs mechanism from IR deformation with arbitrary coupling coefficients to the UV gauge-invariant theory by imposing the tree-level unitarity consistently. I will also briefly discuss about possible phenomenological application of the on-shell massive formalism.

Speaker: Dr Da Liu (UC, Davis)

Massive Amplitude_Pheno_2021.pdf

17:00 Form Factor Effects in Higgs Couplings

The presence of heavy new physics generally alters the Standard Model (SM) Higgs couplings predictions. In many models, momentum effects are assumed to decouple as the heavy states are integrated out. However, these effects can be important in situations of significant off-shellness at collider experiments. In this talk, I will discuss the momentum dependence of different beyond the SM scenarios, using form factors to encode the $p^2$ effect on the Higgs couplings. We show a significant enhancement of order $p^2/\Lambda^2$ over the expected $v^2/\Lambda^2$ predictions for the BSM scenarios studied. These effects are competitive with the momentum independent coupling modifications, changing the predictions of the models. Additionally, the use of form factors modifies the shapes of the kinematic distributions, providing new opportunities for LHC signals.

Speaker: Mr Pedro Bittar (University of São Paulo)

Form_factors.pdf

17:15 Vacuum stability and perturbativity with extended Higgs and neutrinos

The Standard Model (SM) explaining the framework of elementary particles seems to be completed
by the discovery of the SM-like Higgs boson with a mass of about 125 GeV at the Large Hadron
Collider(LHC) in 2012. Despite this success, there are enough experimental evidences, ranging
from observed dark matter (DM) relic density and matter-antimatter asymmetry in the universe
to non-zero neutrino mass, which indicates the existence of beyond SM theories. It is also known
from the theoretical viewpoint that the SM by itself cannot ensure the electroweak (EW) vacuum
stability till the Planck scale. It is observed that an additional scalar sector with bosonic
degrees of freedom can ease the stability issue, by compensating for the destabilizing effect of the
top-quark Yukawa coupling on the renormalization group (RG) evolution of the SM Higgs quartic
coupling. We observed that extension with singlet right-handed neutrinos (RHNs) destabilizes
the potential while in extensions with SU(2) triplet fermions, weak gauge coupling g-2 shows
contrasting behaviour compared to SM and enhances the stability. Extension with singlet right-
handed neutrinos or triplet fermions generated the eV light neutrino mass via seesaw mechanism
while scalar sector i.e. Inert Higgs doublet or Higgs triplet provides a dark matter candidate. After
the theoretical constraints from Planck scale perturbativity and vacuum stability we focussed on
the DM constraints from DM relic density, direct detection and indirect detection of DM. For
the freeze-out scenario, the universe started with a large population of DM that was in thermal
equilibrium with the bath. As the universe expands, the temperature falls down and the dark
matter particles are not able to find each other fast enough to maintain the equilibrium abundance.
So when the equilibrium ends and the freeze-out starts, inert particles can contribute to the DM
relic density through freeze-out mechanism. Firstly, DM can be detected by the so-called direct
detection method via elastic scattering with terrestrial detectors and the quantity that determines
the direct detection rate is the dark matter-nucleon (DM-N) scattering cross-section. Secondly, the
Indirect detection of dark matter is also an interesting way to probe particle dark matter models.
Galactic centre and Dwarf Spheroidal Galaxies (dSphs) are amongst the few targets, where dark
matter annihilate or semi-annihilate into electron, positron, neutrinos, etc. and yield excess of
gamma rays of different energies which are then observed by various telescopes. We estimated
the indirect cross-section constraints for the dominant modes from H.E.S.S. and Fermi-Lat
experiments. We also estimated the production cross-sections for various associated Higgs-DM
production modes at the LHC for the centre of mass energy of 14, 100 TeV in inert Higgs doublet
and inert Higgs triplet (ITM) respectively. It is observed that the compressed spectrum for ITM
will easily lead to displaced mono- or di-charged leptonic or displaced jet final states along with
missing energy while in case of IDM such displaced case is not so natural. We use an extensive
numerical set up, using Calchep, Micromegas 5.0.8, Madgraph, Pythia, Delphes and
Machine learning techniques.

Speaker: SHILPA JANGID (IIT HYDERABAD)

pheno2021_shilpa.pdf

17:30 Off-shell Higgs Couplings in H*→ZZ→ℓℓνν

We explore the new physics reach for the off-shell Higgs boson measurement in the ${pp \to H^* \rightarrow Z(\ell^{+}\ell^{-})Z(\nu\bar{\nu})}$ channel at the high-luminosity LHC. The new physics sensitivity is parametrized in terms of the Higgs boson width, effective field theory framework, and a non-local Higgs-top coupling form factor. Adopting Machine-learning techniques, we demonstrate that the combination of a large signal rate and a precise phenomenological probe for the process energy scale, due to the transverse $ZZ$ mass, leads to significant sensitivities beyond the existing results in the literature for the new physics scenarios considered.

Speaker: Han Qin (University of Pittsburgh)

OffShellHiggs_Pheno2021.pdf

17:45 Directly Probing the Higgs-top Coupling at High Scales

The top-quark Yukawa coupling $y_t$ is the strongest interaction of the Higgs boson in the Standard Model (SM) with $y_t \sim 1$. Due to its magnitude, it plays a central role in Higgs phenomenology in the SM and would be most sensitive to physics beyond the Standard Model. The top Yukawa can be directly measured at the LHC via top pair production in association with a Higgs boson  $t\bar{t}h$. We study new physics effects for the Higgs-top coupling at high scales, using jet substructure techniques. We present the high-luminosity LHC sensitivity to new physics parametrized in the EFT framework and through a general Higgs-top form factor.

Speaker: Roshan Mammen Abraham (Oklahoma State University)

higgs_top_coupling_pheno2021.pdf

18:00 Renormalizable models of flavor-specific scalars

"Singlet scalar mediators have a wide phenomenological application and a variety of SM extensions have been based on them. In this work, we build upon the story of flavor-specific scalars, where the scalar dominantly couples to one specific SM fermion mass eigenstate. This hypothesis meshes well with absence of new flavor changing neutral currents at tree level. Earlier works were based on an EFT framework to implement this hypothesis and focused on the resulting low-energy phenomenology. In this study, we take a step up by describing two different renormalizable completions - one where we introduce a heavy vector-like quark, and another case where we have a second scalar doublet. We study the phenomenology of an "up-philic" scenario in depth, considering the various constraints coming from FCNC, EWPT, CKM and CP violation bounds. We also compare the effects of these limits for both the EFT parameters and the UV parameters, displaying the available parameter space for both the high energy (UV parameters) and the low energy (EFT) parameter space. "

Speaker: Mudit Rai (University of Pittsburgh)

Pheno 2021 Flavour UV completion.pdf

18:15 Merging and Matching in Herwig 7 using HJets

In this talk I will present results of the simulation of electroweak Higgs boson production at the CERN LHC using the Herwig 7 general purpose event generator using one-loop matrix elements via the interface to HJets. The main result will be the simulation of next-to-leading order merging of Higgs boson plus 2 and 3 jets with a dipole parton shower. Additionally, I will comment on non-factorizable radiative corrections to this important Higgs boson production process. I will, also, provide a comparison of the full calculation with the well known t-channel approximation (a.k.a VBF) provided by the parton-level Monte Carlo program, VBFNLO.

Speaker: Terrance Figy (Wichita State University)

Pheno2021-HJets-TFigy

18:30 Recent results in Heavy Flavour and Quarkonia Physics from CMS

The most recent result achieved by the CMS experiment in the field of Heavy Flavour and Quarkonia Physics will be presented and discussed with emphasis to the brand new measurements and observations.

Speaker: Chandiprasad Kar (National Institute of Science Education and Research (IN))

Pheno2021.pdf

16:30 → 18:45 Neutrino III

Convener: Pedro Machado

Zoom link Neutrino III

16:30 CP-Violating Neutrino Non-Standard Interactions in Long-Baseline-Accelerator Data

Neutrino oscillations in matter provide a unique probe of new physics. Leveraging the advent of neutrino appearance data from NOvA and T2K in recent years, we investigate the presence of CP-violating neutrino non-standard interactions in the oscillation data. We first show how to very simply approximate the expected NSI parameters to resolve differences between two long-baseline appearance experiments analytically. Then, by combining recent NOvA and T2K data, we find a tantalizing hint of CP-violating NSI preferring a new complex phase that is close to maximal: $\phi_{e\mu}$ or $\phi_{e\tau}\approx3\pi/2$ with $|\epsilon_{e\mu}|$ or $|\epsilon_{e\tau}|\sim0.2$. We then compare the results from long-baseline data to constraints from IceCube and COHERENT.

Speaker: Dr Peter Denton (Brookhaven National Laboratory)

Denton_LBLNSI.pdf

16:45 Neutrino Decoherence in Simple Open Quantum Systems

Neutrinos lose coherence as they propagate, which leads to the fading away of oscillations. In this work, we model neutrino decoherence induced in open quantum systems from their interaction with the environment. We first present two different models in the quantum mechanical framework, in which the environment is modeled as forced harmonic oscillators with white noise interactions, or two-level systems with stochastic phase kicks. We then look at the decoherence process in the quantum field theoretic framework induced by elastic scatterings with environmental particles. The exponential decay is obtained as a common feature for all models, which shows the universality of the decoherence processes. We also discuss connections to the GKSL master equation approach and give a clear physical meaning of the Lindblad operators.

Speaker: Bin Xu (University of Florida)

pheno2021_BinXu.pdf

17:00 Axial and pseudoscalar form factors from charged current quasielastic neutrino-nucleon scattering

We study the sensitivity to axial nucleon structure of single-spin asymmetries in (anti)neutrino charged current quasielastic scattering on free nucleons. In contrast to electromagnetic processes, the parity-violating weak interaction gives rise to large single-spin asymmetries at leading order. Future polarization measurements could provide independent access to the proton axial structure and allow the first extraction of the pseudoscalar form factor from neutrino data without the conventional partially conserved axial current ansatz and assumptions about the pion-pole dominance. The pseudoscalar form factor can be accessed with precise measurements with muon (anti)neutrinos of a few hundred MeV of energy or with tau (anti)neutrinos. Recoil and target longitudinal asymmetries are the most promising single-spin asymmetries for the extraction of the axial form factor at GeV energies.

Speaker: Oleksandr Tomalak (University of Kentucky)

Tomalak_talk_Pheno2021.pdf

17:15 About distinguishing different neutrinoless double beta mechanisms

Besides the usual mechanism of light Majorana-neutrino exchange nature might have chosen (additional) different mechanisms which could induce neutrinoless double beta decay ( $0\nu\beta\beta$). We studied possibilities on how to experimentally distinguish different $0\nu\beta\beta$-mechanisms on an EFT basis. Additonally, we are developing a general purpose tool to calculate $0\nu\beta\beta$ observables from general EFT models. At the end of the talk an early pre-alpha version of this tool will be presented.

Speaker: Oliver Scholer (Max-Planck Institut für Kernphysik)

Pheno2021Scholer.pdf

17:30 Neutrinoless double beta decay and left-right symmetry

In this talk, I will discuss the progress of neutrinoless double beta decay in the minimal left-right symmetric model. Especially, I will show that due to the left-right mixing, a new leading contribution due to chiral enhancement can guarantee a good prospect for a positive signal in the next generation of neutrinoless double beta decay experiments even confronting with future cosmological surveys.

Speaker: Gang Li

2021_Gang_Li_DBD.pdf

17:45 Explaining the MiniBooNE Excess Through a Mixed Model of Oscillation and Decay

This talk presents a model of the electron-like excess observed by the MiniBooNE experiment comprised of oscillations involving a new mass state, $\nu_4$, at $\mathcal{O}(1)$ eV and a high mass state, $\mathcal{N}$, at $\mathcal{O}(100)$ MeV that decays to $\nu+\gamma$ via a dipole interaction.
Short baseline oscillation data sets (omitting MiniBooNE appearance data) are used to predict the oscillation parameters. We simulate the production of $\mathcal{N}$ along the Booster Neutrino Beamline via both Primakoff upscattering ($\nu A \to \mathcal{N} A$) and Dalitz-like neutral pion decays ($\pi^0 \to \mathcal{N} \nu \gamma$).
The simulated events are fit to the MiniBooNE neutrino energy and visible scattering angle data separately to find a joint allowed region at 95\% CL.
An example point in this region with coupling of $3.6 \times 10^{-7}$ GeV$^{-1}$, $\mathcal{N}$ mass of 394 MeV, oscillation mixing angle of $6\times 10^{-4}$ and mass splitting of $1.3$ eV$^2$ has $\Delta \chi^2/dof$ for the energy and angular fit of 15.23/2 and 37.80/2, respectively.

Speaker: Nicholas Kamp (Massachusetts Institute of Technology)

Pheno2021_Kamp.pdf

18:00 Correlating Muon g−2 Anomaly with Neutrino Magnetic Moments

We have analyzed new contributions to the muon anomalous magnetic moment in a class of models that generates a naturally large transition magnetic moment for the neutrino (needed to explain the XENON1T electron recoil excess). These models are based on an approximate $SU(2)_H$ symmetry that suppresses the neutrino mass while allowing for a large neutrino transition magnetic moment. We have shown that the new scalars present in the theory with masses around 100 GeV can yield the right sign and magnitude for the muon $g−2$ which has been confirmed recently by the Fermilab collaboration. Such a correlation between muon $g−2$ and the neutrino magnetic moment is generic in models employing leptonic family symmetry to explain a naturally large $μ_{\nu_μ ν_e}$. We have also outlined various other experimental tests of these models at colliders. Results will be presented.

Speaker: Dr Sudip Jana (Max-Planck-Institut für Kernphysik)

Pheno2021_Sudip.pdf

18:15 The Singly-Charged Scalar Singlet as the Origin of Neutrino Masses

We consider the generation of neutrino masses via a singly-charged scalar singlet. Under general assumptions we identify two distinct structures for the neutrino mass matrix. This yields a constraint for the antisymmetric Yukawa coupling of the singly-charged scalar singlet to two left-handed lepton doublets, irrespective of how the breaking of lepton-number conservation is achieved. The constraint disfavours large hierarchies among the Yukawa couplings. We study the implications for the phenomenology of lepton-flavour universality, measurements of the $W$-boson mass, flavour violation in the charged-lepton sector and decays of the singly-charged scalar singlet. We also discuss the parameter space that can address the Cabibbo Angle Anomaly.

Speaker: Tobias Felkl (University of New South Wales)

talk-pheno2021-felkl.pdf

18:30 Detecting and studying high-energy neutrinos with FASERnu at the LHC

FASER$\nu$ at the LHC is designed to directly detect collider neutrinos for the first time and study their cross sections at TeV energies, where no such measurements currently exist. The detector will be located 480 m downstream of the ATLAS interaction point. With FASERnu, the three-flavor neutrino cross-sections will be measured in the currently unexplored energy range between 360 GeV and 5 TeV. In particular, tau-neutrino and electron-neutrino cross sections will be measured at the highest energy ever. From the other perspective, FASERnu can measure forward neutrino production, and provide novel constraints on forward particle production.

In 2018 we performed a pilot run with the aims of measuring particle fluxes at the proposed detector location and of possibly detecting neutrino interactions for the first time at the LHC. We installed a 30-kg lead/tungsten emulsion detector and collected data of 12.2 fb$^{-1}$. The analysis of this data has yielded several neutrino interaction candidates, excluding the no-signal hypothesis at the 2$\sigma$ level.

During Run-3 of the LHC starting from 2022, we will deploy an emulsion detector with a target mass of 1.1 tons, coupled with the FASER magnetic spectrometer. This would yield roughly 2,000 $\nu_e$, 7,000 $\nu_{\mu}$, and 30 $\nu_{\tau}$ interacting in the detector. Here we present the status and plan of FASER$\nu$, as well as the neutrino detection in the 2018 data.

Speaker: Tomoko Ariga (Kyushu University (JP))

20210526_tariga_FASERnu_Pheno_v2.pdf

16:30 → 18:45 QCD & EW II

https://pitt.zoom.us/j/95003092770

Convener: Tobias Neumann (Brookhaven National Laboratory)

Zoom

16:30 Jet and Photon Measurements using the ATLAS detector

The production of jets and prompt isolated photons at hadron colliders provides stringent tests of perturbative QCD and are sensitive to parton distribution functions in the proton. In this talk we discuss the most recent measurements done using proton-proton collision data collected by the ATLAS experiment at √s=13 TeV with full Run-2 dataset. For what concerns measurement with photons, a measurement of photon pair production is presented. For multijet production, we show a measurement of event shape variables calculated using hadronic jets. Measurements of jet production are also sensitive to the strong coupling constant, a measurement extremely sensitive to the strong coupling constant is discussed. Finally, if available new measurements will be shown. All measurements are corrected for detector effects and are compared to the predictions of state-of-the-art Monte Carlo event generators.

Speaker: Christian Wiel (Technische Universitaet Dresden (DE))

ATL-COM-PHYS-2021-239.pdf

16:45 Multi-boson production including photon-photon fusion at ATLAS

Measurements of multiple electroweak bosons production and vector boson scattering, as well as photon-photon fusion at the LHC are stringent tests of the electroweak sector and provide a model-independent means to search for new physics at the TeV scale. In this talk, we present the most recent results on multi-boson production in proton-proton collisions at √s=13 TeV performed by the ATLAS experiment with the full Run-2 dataset. Differential cross sections of inclusive diboson final states and diboson final states in association with jets are measured and the data are compared to predictions. Reinterpretation in terms of an effective field theory to constrain new physics beyond the Standard Model are also presented. Finally, we will also present results of the observation of photon-induced WW production. If available, new results will be also presented.

Speaker: Prajita Bhattarai (Brandeis University (US))

PHENO2021PrajitaBhattarai_MultibosonProduction.pdf

17:00 Towards Mixed QCD-EW corrections to Drell-Yan processes beyond resonance region

We present the progress towards calculation of necessary ingredients for the mixed QCD-EW corrections to Drell-Yan processes outside the resonance region, where new physics searches are potentially relevant.

Speaker: Syed Mehedi Hasan (INFN Sezione di Pavia)

Pheno 2021_Syed.pdf

17:15 RESOLVING THE DILEPTONIC tt COMBINATORIAL PROBLEM

Measurement of Top quark properties takes advantage of the cleanness of the dilepton channel of top quark pair production. However, it is challenging to reconstruct the full final state kinematically due to the missing transverse momentum arising from two neutrinos, and a two-fold ambiguity in assigning the correct b-jet lepton. I will provide an overview of several existing methods to resolve the two-fold ambiguity, and introduce new attempts using machine learning.

Speaker: Zhongtian Dong (University of Kansas)

Pheno21.pdf

17:30 Quark and Gluon Contents of a Lepton at High Energies

After the triumph of discovering the Higgs boson at the CERN Large Hadron Collider, people are getting increasingly interested in studying the Higgs properties in detail and searching for the physics beyond the Standard Model (SM). A multi-TeV lepton collider provides a clean experimental environment for both the Higgs precision measurements and the discovery of new particles. In high-energy leptonic collisions, the collinear splittings of the leptons and electroweak (EW) gauge bosons are the dominant phenomena, which could be well described by the parton picture. In the parton picture, all the SM particles should be treated as partons that radiated off the beam particles, and the electroweak parton distribution functions (EW PDFs) should be adopted as a proper description for partonic collisions of the initial states. In our work, both the EW and the QCD sectors are included in the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) formalism to perturbatively resum the potential large logarithms emerging from the initial-state radiation (ISR). I will show the results of QCD jet production as well as some other typical SM processes at a possible high-energy electron-positron collider and a possible high-energy muon collider obtained using the PDFs.

Speaker: Yang Ma (University of Pittsburgh)

Pheno2021.pdf

17:45 W+ W- H production through bottom quarks fusion at hadron colliders

With the standard model working well in describing the collider data, the focus is now
on determining the standard model parameters as well as for any hint of deviation. In particular, the
determination of the couplings of the Higgs boson with itself and with other particles of the model
is important to better understand the electroweak symmetry breaking sector of the model. In this
letter, we look at the process pp → W W H, in particular through the fusion of bottom quarks. Due
to the non-negligible coupling of the Higgs boson with the bottom quarks, there is a dependence
on the W W HH coupling in this process. This sub-process receives largest contribution when the W
bosons are longitudinally polarized. We compute one-loop QCD corrections to various final states with polarized W bosons. We find that the corrections to the final state with the longitudinally polarized W bosons are large. It is shown that the measurement of the polarization of the W bosons can be used as a tool to probe the W W HH coupling in this process. We also examine the effect of varying W W HH coupling in the κ-framework.

Speaker: Biswajit Das (Institute Of Physics, Bhubaneswar, India`)

pheno_2021_biswajit.pdf

18:00 Resurgence of the QCD Adler function

We study the QCD Adler function in the energy region $\approx 0.7-2.5$ GeV, in which the non-perturbative effects become dominant. Our analysis is a renormalon-based evaluation using transseries within the resurgence of the Renormalization-Group-Equation and does not require the Operator-Product-Expansion.

Speaker: Dr Juan Carlos Vasquez (University of Massachusetts Amherst)

talk_Juan_Vasquez.pdf

18:15 Measurements of V+jets production in CMS

The study of the associated production of vector bosons and jets constitutes an excellent environment to check numerous QCD predictions. Total and differential cross sections of vector bosons produced in association with jets has been studied at CMS. Differential distributions as function of a broad range of kinematical observables are measured and compared with theoretical predictions. These processes are very important to understand, and they constitute an important source of background for Higgs boson production measurements, and searches for new particles.

Speaker: Dr Kadir Ocalan (Necmettin Erbakan University (TR))

k.ocalan_pheno2021.pdf

18:30 Top quark pair and single top cross sections in CMS

Top quark pair and single top cross sections in CMS

Speaker: Javier Cuevas (Universidad de Oviedo (ES))

tt-singletop-pheno21.pdf

16:30 → 18:45 Theoretical developments & Extra dimensions

https://pitt.zoom.us/j/98404207205

Convener: Peizhi Du (Stony Brook University)

zoom

16:30 An Environmental Solution to the Strong CP Problem

A theory that solves the strong CP problem without an axion, makes use of the background properties of a (very) low mass vector dark matter particle, whose spin density is driven to align in such a way as to cancel the theta-bar term.

Speaker: Tim M.P. Tait (University of California, Irvine)

tait-Pheno2021.pdf

16:45 Lorentz Invariance from Locality of Massless Spin 2

It is known that local, Lorentz invariant, unitary theories involving particles with spin 1 demand
that the matter sector they couple to are organized by internal physical symmetries and the as-
sociated charge conservation, while spin 3/2 demands supersymmetry. However, the introduction
of a spin 2 graviton does not obviously demand new symmetries of the matter sector (although it
does demand a universal coupling). In recent work we relaxed the assumption of Lorentz boost symmetry, while maintaining a basic notion of locality that there is no instantaneous signaling at a distance. In order to avoid potential problems with longitudinal modes of the graviton, we chose to project them out, leaving only two degrees of freedom. This nevertheless leaves a large classes of theories that a priori may violate Lorentz boost invariance. By requiring the tree-level
exchange action be local, consistency demands that the Lorentz boost symmetry must be satisfied by the graviton and the matter sector, which in turn recovers general relativity uniquely at this
order of analysis. In this sense, the Lorentz boost symmetry can be seen to be an underlying physical symmetry that is demanded of the graviton and matter sectors, analogous to internal symmetries of theories involving spin 1, a fact which is usually taken for granted.

Speaker: Jacob Litterer (Tufts University)

JLittererPheno21.pdf

17:00 Scattering Amplitudes of Massive Spin 2 particles in extra dimensional theories

We present a first complete calculation of scattering amplitudes of massive spin-2 Kaluza Klein resonances in extra dimensional theories. Although individual contributions of Kaluza-Klein particle scattering can grow as fast as $E^{10}$, intricate cancellations ensure that the full scattering amplitudes grow only as fast as $E^2$. We provide the necessary sum-rules that ensure such cancellations and describe the anatomy of these scattering amplitudes in both flat-toroidal as well as warped models in Anti-De-Sitter space. We contrast this calculation with theories of massive gravity and its extensions.

Speaker: dipan sengupta

Dipan_Pheno.pdf

17:15 Scattering Amplitudes of Massive Spin-2 Particles in Extra Dimensional Theories

We present a first complete calculation of scattering amplitudes of massive spin-2 Kaluza Klein resonances in extra dimensional theories. Although individual contributions of Kaluza-Klein particle scattering can grow as fast as $E^{10}$, intricate cancellations ensure that the full scattering amplitudes grow only as fast as $E^2$. We provide the necessary sum-rules that ensure such cancellations and describe the anatomy of these scattering amplitudes in both flat-toroidal as well as warped models in Anti-De-Sitter space. We contrast this calculation with theories of massive gravity and its extensions.

Speaker: Kirtimaan Mohan (Michigan State University)

Kirtimaan_Mohan_PHENO_2021.pdf

17:30 geoSMEFT and some applications

The geometric approach to the SMEFT is defined, and some applications of this approach to Higgs and Electroweak physics is discussed.

Speaker: Michael Robert Trott (University of Copenhagen (DK))

pheno2021.pdf

17:45 A Real Time Approach to Quantum Tunneling

Recently there has been increasing interest in alternate methods to compute quantum tunneling in field theory. Of particular interest is a stochastic approach which involves (i) sampling from the free theory Gaussian approximation to the Wigner distribution in order to obtain stochastic initial conditions for the field and momentum conjugate, then (ii) evolving under the classical field equations of motion, which leads to random bubble formation. Previous work showed parametric agreement between the logarithm of the tunneling rate in this stochastic approach and the usual instanton approximation. However, recent work claimed excellent agreement between these methods. Here we show that this approach does not in fact match precisely; the stochastic method tends to overpredict the instanton tunneling rate. To quantify this, we parameterize the standard deviations in the initial stochastic fluctuations by $\epsilon*\sigma$, where $\sigma$ is the actual standard deviation of the Gaussian distribution and $\epsilon$ is a fudge factor; $\epsilon$ = 1 is the physical value. We numerically implement the stochastic approach to obtain the bubble formation rate for a range of potentials in 1+1-dimensions, finding that $\epsilon$ always needs to be somewhat smaller than unity to suppress the otherwise much larger stochastic rates towards the instanton rates; for example, in the potential of Braden, et. al. one needs $\epsilon$ ~ 1/2. We find that a mismatch in predictions also occurs when sampling from other Wigner distributions, and in single particle quantum mechanics even when the initial quantum system is prepared in an exact Gaussian state. If the goal is to obtain agreement between the two methods, our results show that the stochastic approach would be useful if a prescription to specify optimal fudge factors for fluctuations can be developed.

Speaker: Neil Shah (Tufts University)

Neil_Shah_Pheno_2021_Stochastic_Tunneling_Talk - Copy.pdf

18:00 The Chirality-Flow Formalism for Amplitude Calculations

Scattering amplitudes are often split up into their gauge (su(N)) and kinematic (two copies of complexified su(2)) components. Since the su(N) gauge part is often calculated using flows of colour, it should similarly be possible to describe the su(2) \oplus su(2) kinematics of an amplitude in terms of flows of chirality. In two recent papers (hep-ph:2003.05877 & hep-ph:2011.10075) we showed that this is indeed the case, introducing the chirality-flow formalism for Standard Model calculations. In the chirality-flow method (which simplifies the spinor-helicity method) Feynman diagrams can be directly written down in terms of Lorentz-invariant spinor inner products, allowing the simplest and most direct possible path from Feynman diagram to complex number. In this talk, I will introduce this method and show some examples.

Speaker: Andrew Lifson (Lund University)

ALPheno21.pdf

18:15 Real Classical Geometry with arbitrary deficit parameter(s) $\alpha_I$ in Deformed Jackiw-Teitelboim Gravity

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\title{\Large \bf Real Classical Geometry with arbitrary deficit parameter(s) $\alpha(_{I})$ in Deformed Jackiw-Teitelboim Gravity}

\author{Davood Momeni}
\email{davood@squ.edu.om}
\affiliation{Department of Physics, College of Science, Sultan Qaboos University, P.O. Box 36, \Al-Khodh 123, Muscat, Sultanate of Oman}
%\affiliation{Center for Space Research, North-West University, Mafikeng, South Africa}
%\affiliation{Tomsk State Pedagogical University, TSPU, 634061 Tomsk, Russia}
\begin{abstract}
An interesting deformation of the Jackiw-Teitelboim (JT) gravity has been proposed by Witten by adding a potential term $U(\phi)$ as a self-coupling of the scalar dilaton field. During calculating the path integral over fields, a constraint comes from integration over $\phi$ as $R(x)+2=2\alpha \delta(\vec{x}-\vec{x}')$. The resulting Euclidean metric suffered from a conical singularity at $\vec{x}=\vec{x}'$. A possible geometry modeled locally in polar coordinates $(r,\varphi)$ by $ds^2=dr^2+r^2d\varphi^2,\varphi \cong \varphi+2\pi-\alpha$. In this letter we showed that there exists another family of "exact" geometries for arbitrary values of the $\alpha$. A pair of exact solutions are found for the case of $\alpha=0$. One represents the static patch of the AdS and the other one is the non static patch of the AdS metric. These solutions were used to construct the Green function for the inhomogeneous model with $\alpha\neq 0$. We address a type of the phase transition between different patches of the AdS in theory because of the discontinuity in the first derivative of the metric at $x=x'$. We extended the study to the exact space of metrics satisfying the constraint
$R(x)+2=2\sum_{i=1}^{k}\alpha_i\delta^{(2)}(x-x'_i)$
as a modulo diffeomorphisms for an arbitrary set of the deficit parameters $(\alpha_1,\alpha_2,..,\alpha_k)$. The space is the moduli space of Riemann surfaces of genus $g$ with $k$ conical singularities located at $x'_k$ denoted by $\mathcal{M}_{g,k}$.
\end{abstract}

%\pacs{Valid PACS appear here}

%\pacs{Valid PACS appear here}

\maketitle
\date{\today}

%%%%%%%%%%%%%%%%%%%%%%
\section{introduction}
One of the most exciting branches of the current research is finding duality between an exactly solvable lower dimensional quantum system and certain types of the bulk theories with gravity. This duality was inspired by AdS/CFT where at the specific regimes of the coupling, the certain types of the string theories (with gravity) are mapped to strongly coupled large $N$ CFT theories on the flat boundary of the AdS spacetime \cite{Maldacena:1997re}. Depending on the gravitational sector in the bulk, the resultant boundary quantum theory could be different from the CFT one , as well as the bulk could be a non blackhole background. Some basic deformations of AdS/CFT are dualities between asymptotically AdS spaces and QFTs with UV fixed points. For example pure AdS is dual to zero temperature CFTs , blackholes on AdS are duals to finite temperature CFTs while the AdS soliton is dual to QFT with mass gap. The idea of making exact duality between realistic condensed matter systems (exactly solvable) and blackhole physics work initiated with the simple Kitaev model \cite{Kitaev2015} and later its dual bulk theory investigated widely in \cite{Polchinski:2016xgd,Maldacena:2016hyu}. For certain types of exact solvable Kitaev models, the holographic bulk investigated via gauge/gravity duality. In the Ref.\cite{Saad:2019lba}, the authors demonstrated the duality between random Hermitian matrix theory (RMT) and the corresponding $2d$ bulk theory with gravity. Gravity in $2d$ is very special and been well studied in past in several works by many authors , see for example \cite{Bagrets:2016cdf}-\cite{Iliesiu:2019xuh} . A reason for such wide study was firstly its ultraviolet (UV) divergence free form along its simplicity and secondly its viable physical interpretations in the context of the string theory. Gravity in $2d$ can be understood as a dilaton gravity as well as a natural reduction of the standard classical general relativity (GR) action from a higher $D$ gravities to $D=2$, see e.g.\cite{Grumiller:2002nm}. Furthermore, Euclidean fully integrable forms of theory in $2d $ were studied in \cite{Bergamin:2004pn}.\par
JT gravity is a family of scalar field theories where the scalar field(dilaton) $\phi$ coupled to gravity in two dimensions as a minimal theory of gravity in $2d$ \cite{Jackiw:1984je,Teitelboim:1983ux}. it is possible to remove UV divergences in two dimensional bulk theory for gravity, as a result it can be considered as a potentially "toy" model for qunatum gravity. A rigorous derivation of the pure JT gravity action can be softly done using a {\it tricky} conformal transformations in $D$ dimensions and then taking the limit of $D\to 2$ \cite{Mann:1992ar}.
\par
The Euclidean action of the pure JT gravity with a negative cosmological constant is represented by
\begin{eqnarray}\label{jt}
S=-\frac{1}{2}\int_{\Omega} d^2x\sqrt{g}(\phi R+2\phi) + \partial S_{bdy}
\end{eqnarray}
where $\partial S_{bdy}$ stands for any boundary topological term (or the usual GHY boundary term) , e.g. Euler characteristic, $R$ is the Ricci scalar curvature of the Euclidean metric tensor $g_{\mu\nu},\mu,\nu=0,1$. By $\Omega$ we mean a region of the spacetime with(without) boundary. It has been demonstrated that the JT gravity action given in (\ref{jt}) enjoys several interesting features from symmetry up to solvability of the equations of the motion (EoMs), see for example the works done by Refs.\cite{Almheiri:2014cka,Maldacena:2016upp,Engelsoy:2016xyb,Harlow:2018tqv}. If one adds nontrivial couplings between the dilaton and the Abelian $1$-form, the model still shows several physical properties as an exact solvable model
\cite{Lala:2019inz}. In Ref. \cite{Mertens:2019tcm} the authors studied defects in the JT gravity holographically by studying the deformation of the Schwarzian theory as the dual qunatum boundary action.
\par
Very recently a deformation of the pure JT gravity proposed by
Witten \cite{Witten:2020wvy}. The model still has RMT dual as a boundary gauge theory in a similar manner as the original JT gravity \cite{Witten:2020ert}(see \cite{Maxfield:2020ale} also for RMT dual and the relation between critical $3d$ gravity and JT) . Witten investigated a simple deformation of JT gravity by adding a potential term $U(\phi)$ as a self-coupling of the scalar dilaton field. The model reduced to pure JT and furthermore remarkable observation was that the density of energy levels is different from the pure JT. The action for deformed JT (dJT) as proposed
in Ref.\cite{Witten:2020ert} takes the form
\begin{eqnarray}
S=-\frac{1}{2}\int_{\Omega} d^2x\sqrt{g}\Big(\phi R + U(\phi)\Big)\,.\label{ddJT}
\end{eqnarray}
In this work we will study the above model
as proposed in Ref. \cite{Witten:2020ert} for $U(\phi)=2\phi + W(\phi)$ , where $W(\phi)$ is
\begin{eqnarray}
&&W(\phi)=2\sum_{i=1}^{r}\epsilon_{i}\exp{-\alpha_i \phi},\ \ \pi<\alpha<2\pi\label{potential}
\end{eqnarray}
To write the above potential function, we assume that the potential function $U(\phi)\sim 2\phi, \ \ \phi\to +\infty$. It is required to get JT theory in the asymptotic limit $\phi\to \infty $. One possible constraint to satisfy the above requirement is to restrict the potential to be as follows,
\begin{eqnarray}\label{delta}
&&\lim_{\phi\to +\infty}|\phi^{1+\delta}(U(\phi)-2\phi)|<1,\ \ \delta \geq 1.
\end{eqnarray}
One possible simple form for such potential function is the one written in expression (\ref{potential}).
%%%%%%%%%%%%%%%%%%%%%%%%%
A remarkable program for the qunatization of the JT gravity like theories and viable higher order corrections to it widely studied in the
in Refs. \cite{Nojiri:2000ja}-\cite{Nojiri:2020tph}.
%%%%%%%%%%%%%%%%%%%%
Some new exact solutions for dJT studied recently in \cite{Momeni:2020zkx} in favor of the Maldacena's duality conjecture and boundary Schwarzian theories. In Ref. \cite{Momeni:2020zkx} we showed that how pure AdS seed metric for pure JT gravity will be deformed in the dJT. In this work we continued our study about dJT.
The problem we want to address here is how this perturbative potential (\ref{potential}) will deform the pure JT gravity bulk geometry. The problem statement will be clearly present
in Sec.\ref{JT}. It will be formulated on a conformal gauge for Euclidean metric as a nonlinear PDE.
\par
The structure of the paper is as follows. In Sec.\ref{JT} we formulate the problem of the deformed singular metrics with a single deficit parameter $\alpha$. In Sec.\ref{sec3}, we formulate weak problem via integral balance technique . In addition, we construct Green function as a solution for the nonlinear PDE formulated in Sec.\ref{dJT}.
Moreover, in Sec.\ref{nonmini}, we introduce the phase transition from AdS to AdS in dJT. In Sec VI blackhole solutions studied with more than one deficit parameters. In Sec VII a brief discussion given about time dependent geometries with singularity. We finally conclude our results in the last section.
%%%%%%%%%%%%%%%%%%%%%%
\section{Problem statement }\label{JT}
The Euclidean action for dJT theory eq. (\ref{ddJT}) with potential function (\ref{potential}) for $\epsilon_{r}=0$ coincides to the pure JT gravity. The aim is to compute the Euclidean path integral (EPI) for first order $\mathcal{O}(\epsilon)$ perturbatively . Following the assumptions made by Witten, it is possible to take the bulk action of order $\epsilon$ for a typical exponential dilatonic potential given by $U(\phi)=2\epsilon e^{-\alpha\phi }$ in the following form
\begin{eqnarray}&&
I=I_{JT}-\epsilon \int \sqrt{g}d^2x e^{-\alpha \phi}\end{eqnarray}
There are higher order terms of $\mathcal{O}(\epsilon^2),n\geq 2$ will be considered if one is interested to see the effects of higher orders. For simplicity we kept the term of order one. The EPI is explicitly written in a perturbative form as the following,
\begin{eqnarray}
&&EPI=\int D\phi Dg \exp{-I_{JT}}+\epsilon \int D\phi Dg \exp{-I_{JT}}\int d^2 x_1\sqrt{g(x_1)}e^{-\alpha\phi }+\mathcal{O}(\epsilon^2)
\end{eqnarray}
If we only consider the pure JT gravity, the EPI reduces to the partition function of the JT gravity. The first order correction needs an evaluation of an integral in the following form (after a normalization to the volume)
\begin{eqnarray}
&&\int D\phi Dg \exp{\frac{1}{2}\int d^2x_2\sqrt{g(x_2)}(R+2)\phi(x_2) }\int d^2 x_1\sqrt{g(x_1)}e^{-\alpha\phi(x_1) }
\end{eqnarray}
The trick to calculate the following integral is to write $\phi(x_2)=\int d^2x_1 \sqrt{g(x_1)} \phi(x_1)\delta(x_1-x_2)$ where the Dirac delta function is defined as
\begin{eqnarray}
&&\int \sqrt{g(x_1)}d^2x_1 \delta(x_1-x_2)=1\label{delta}
\end{eqnarray}
using this field representation, we have
\begin{eqnarray}
\int d^2x_1 \sqrt{g(x_1)} \int D\phi Dg \exp{\frac{1}{2}\int d^2x_2\sqrt{g(x_2)} \phi(x_2)\Big(R(g(x_2))+2-2\alpha\delta(x_2-x_1)\Big)}
\end{eqnarray}
We interchange the integration orders, firstly by taking the integral over field $\phi$ ,
\begin{eqnarray}
&&\int Dg \delta(\frac{1}{2}(R(g(x_2))+2-2\alpha\delta(x_2-x_1)))
\end{eqnarray}
The above delta integral can be reduced to a simpler form via the following functional delta function formula,
\begin{eqnarray}
&&\int Dg \delta(f(g))=\int Dg \sum_{i=1}\frac{\delta f(g)}{\delta g}|{g=g_i}\delta(g-g_i)
\end{eqnarray}
the functional in our case is $f(g)=\frac{1}{2}((R(g(x_2))+2-2\alpha\delta(x_2-x_1))$ and the roots $g_i$ lies on the hypersurface given by $R(g_i(x_2))+2-2\alpha\delta(x_2-x_1)$ in the functional space. Furthermore $\frac{\delta f(g)}{\delta g}|_{g=g_i}=\frac{\delta R}{\delta g}|_{g=g_i}=R^{\mu\nu}|_{g=g_i}\delta g_{\mu\nu}$. Using the above consideration one can complete the partition function steps adequately. The constraint appeared here defines a specific geometry for the metric $g_{\mu\nu}(x_2)$. If one can solve the following partial differential equation (PDE) for $\alpha\neq 0$, we can find the specific geometry for the hypersurface. This is the main task of our paper and we formulate the problem as the following:
\begin{problem}
Find all exact two dimensional  geometries satisfying the constraint equation:\begin{eqnarray}&&R(x)+2=2\alpha \delta (x-x'),\ \  \alpha\neq 0
\label{problem}
\end{eqnarray}
The resulting geometries suffer from a conical singularity at $x=x'$.Â
\end{problem}
In the Witten's paper, it has been claimed that the geometry "can be modeled locally" by a conical flat geometryÂ
\begin{eqnarray}&& ds^2=dr^2+r^2d\varphi^2,\varphi \cong \varphi+2\pi-\alpha
\end{eqnarray}
and later it has been claimed that "there is no real classical geometry " for $\alpha> 2\pi$. In this paper we show that there is classical geometry for any arbitrary value of the $\alpha$. The problem of finding a solution to this problem reduces to constructing proper Green function for a non linear operator. Before we solve the above problem and find "exact" non trivial geometry for it, in the next section we will give a physics to the deficit parameter $\alpha$ via the method of integral balance.
%%%%%%%%%%%%%%%%%%
\section{The integral balance method and the meaning of $\alpha$}\label{sec3}
The method of integral balance is trying to formulate the weak problem for a given general PDE \cite{Yehuda Pinchover}. Indeed, we know that there is a naive connection between an integral balance and the associated differential operator equation. It is worth mentioning here that the method of integral balance is more fundamental and can only be inverted into a PDE form, when the field functions are sufficiently smooth. Because we need the explicit form of the PDE for our problem formulated in the previous section, i.e, (\ref{problem}) , we adopt an Euclidean two dimensional geometry in the following null coordinates
\begin{eqnarray}
ds^2=e^{\psi(u,v)}dudv,\ \ u=z+t,v=z-t
\end{eqnarray}
here $t$ is the Euclidean time.
An explicit expression for the Ricci scalar is $R=-4e^{-\psi}\partial_u\partial_v\psi$. Because we have to satisfy the normalization condition given in eq. (\ref{delta}), we multiply both sides of the equation (\ref{problem}) by factor $\sqrt{g}=\frac{1}{2}e^{\psi(u,v)}$, by dropping the factor $2$, we obtain the following nonlinear PDE,
\begin{eqnarray}
&& \underbrace{\frac{e^{\psi}}{2}}{\sqrt{g}}
-\partial_u\partial_v\psi=\alpha \underbrace{\frac{e^{\psi}}{2}}{\sqrt{g}} \delta(u-u')\delta(v-v')\label{PDE1}
\end{eqnarray}
Now the Problem simplifies to find a non trivial solution for the non linear inhomogeneous PDE eq. (\ref{PDE1}). Actually the solution is nothing but the Green equation for any "arbitrary value of the deficit parameter $\alpha$. We use the term of Green equation and consequently the non trivial solution for the above PDE is basically a Green function defined in the following form
\begin{eqnarray}
&& \hat{O} G(x|x')= \frac{\alpha}{2}\exp{G(x|x')} \delta(u-u')\delta(v-v')\label{green1}
\end{eqnarray}
where the non linear differential operator $\hat{O}$ is defined as
\begin{eqnarray}
&&\hat{O}[..]\equiv \frac{e^{[..]}}{2}-\partial_u\partial_v[..]\label{O}
\end{eqnarray}
and $\psi\equiv G(x|x'), \ \ x\equiv (u,v)$. Although the operator is not Hermitian (we will check it later) or linear but we are very lucky to have at least two exact solutions for it. One exact solution for the operator found in Ref.\cite{Momeni:2020zkx}. That solution corresponds to the pure AdS metric written in the null coordinates. The other solution as we will show in the next section will represent another AdS solution but in the non static patch (cosmological patch). Both solutions are exact solutions and will be used effectively to find Green function in the next section. Solving the above PDE is our plan in the next section.\par
Let us see whether the operator $\hat{O}$ is self adjoint on the domain $\Omega_2 $ as compact version of the real domain $\Omega_1$.
We know that the usual Euclidean AdS (half plane) coordinates (hyperbolic geometry) are living in the following domain
\begin{eqnarray}
&&\Omega_1={z,t\in (0,\infty)\times (-\infty,+\infty)}
\end{eqnarray}
the above non compact domain will be mapped to another non compact null domain,
\begin{eqnarray}
&&\Omega_2={u,v\in(u{-},u_{+})\times(v_{-},v_{+})}
\end{eqnarray}
basically $|u_{\pm}|,|v_{\pm}|\to \infty $ but we kept it as some types of the "conformal boundaries" for the new mapping domain which actually live in very far away region. We know that the operator is self-adjoint operator (or equivalently, a Hermitian operator) if and only if for a pair of the functions, it satisfies the following integral ,
\begin{eqnarray}
&&\int_{\Omega} \sqrt{g}dudv \Phi_1^{}(u,v)\hat{O}\Phi_2(u,v)=
\int_{\Omega} \sqrt{g}dudv \Big(\hat{O}\Phi_1(u,v)\Big)^{}\Phi_2(u,v)\label{selfadjoint}
\end{eqnarray}
We simply use the usual definition of the self-adjoint operator on a Hilbert space in the finite-dimensional space, the only difference backs to the integral measure, instead of the flat space we use the covariant volume element. It is illustrative to mention here that the partial derivative term in the (\ref{O}), looks just like a kinetic energy operator, consequently is a Hermitian term , while the first exponential part doesn't satisfy the (\ref{selfadjoint}) conditions. As a result the operator is non Hermitian (not self-adjoint). But at the end of day, still the operator enjoys some linearity at the level of solutions. That means for a pair of exact solution for the operator, i.e, the kernel pair functions $\psi_{1,2}(u,v)$,
\begin{eqnarray}
&&\hat{O}\psi_{1,2}(u,v)=0\label{kernel}
\end{eqnarray}
one can show that the solutions remain linear independent even when the operator is nonlinear by itself. In the Language of the PDEs, the partial Wronskian of the functions is non zero. The partial Wronskian for solutions, $W_u(\psi_1,\psi_2)$ is
\begin{eqnarray}
&&W_u(\psi_1,\psi_2)=\psi_1\partial_u\psi_2-\psi_2\partial_u\psi_1
\end{eqnarray}
We will prove it later in next section (\ref{dJT}).
In this section we only focus on studying a special discrete regime of the above PDE, i.e, the integral balance technique. We integrate the PDE (\ref{PDE1}) from the lower to the upper boundaries, we obtain,
\begin{eqnarray}
&&\underbrace{\frac{1}{2}\int_{v_{-}}^{v_{+}}dv \int_{u_{-}}^{u_{+}}e^{\psi}du}\text{Entirely space volume} -\int{v_{-}}^{v_{+}}dv \int_{u_{-}}^{u_{+}}du\partial_u\partial_v\psi=\alpha \underbrace{\int_{v_{-}}^{v_{+}}dv \int_{u_{-}}^{u_{+}} \frac{1 }{2} \delta(u-u')\delta(v-v')e^{\psi}du}{1}
\label{balance1}
\end{eqnarray}
We assume that $u_{-} \begin{eqnarray}
&&\alpha=V{tot}-\psi(u_{+},v_{+})+\psi(u_{+},v_{-})+\psi(u_{-},v_{+})-\psi(u_{-},v_{-})\label{PDE3}
\end{eqnarray}
The relation (\ref{PDE3}) is considered as weak problem version of the original (\ref{problem}). In particular it is suitable to integrate numerically and find the metric profile function $\psi$. The physical meaning of the $\alpha$ is encoded in (\ref{PDE3}): the deficit parameter $\alpha$ is the particular volume of the spacetime by excluding the upper $\psi(u_{+},v_{+})$ and lower $\psi(u_{-},v_{-})$ values of the metric function and including the corner sides. We now demonstrate the construction of a weak solution $\psi(u,v) $ that is a continuously differentiable function over the whole plane. The only exception is for discontinuities along a curve $u=\gamma(v)$. Because the solution is smooth on both sides of $\gamma$ , it is easy to show that it satisfies the PDE (\ref{PDE1}). We write the weak solution in the following form
\begin{eqnarray}
&&\psi(u_{-},u_{+}|v)=\int_{u_{-}}^{u_{+}} du \psi(\zeta,v)d\zeta\end{eqnarray}By plugging it to the (\ref{PDE1}) and integration we obtain
\begin{eqnarray}
&&\frac{1}{2}\exp{\int_{u_{-}}^{u_{+}} du \psi(\zeta,v)d\zeta}-\partial_v(\psi(u_{+},v)-\psi(u_{-},v))=\alpha \label{weak1}
\end{eqnarray}
We need to compute $\gamma$. For this purpose we write the weak formulation (\ref{weak1}) in the form
\begin{eqnarray}
&&\frac{1}{2}\exp{\int_{u_{-}}^{\gamma(v)} \psi(\zeta,v)d\zeta+\int_{\gamma(v)}^{u_{+}} \psi(\zeta,v)d\zeta}-\partial_v(\psi(u_{+},v)-\psi(u_{-},v))=\alpha \label{weak}
\end{eqnarray}
Differentiating the above integrals with respect to $\gamma$ and using the PDE itself and after performing the integration we can show that the curve $\gamma$ propagates  at uniform speed. The speed is the given by
\begin{eqnarray}
&&\frac{dv}{d\gamma}=\frac{\partial_v\psi(u_{+},v)-\partial_v\psi(u_{-},v)}{ \partial_v \psi(u_{-},u_{+}|v)}
\end{eqnarray}
the average of the propagation speeds on the left and right ends. After this interpretation, we go back to solving the PDE (\ref{PDE1}) and finding the metric functions which are associated with it.

%%%%%%%%%%%%%%%%%%%%
\section{ Constructing Green function}\label{dJT}
The metric function $\psi(x,x')$ defines Green functions for the non linear differential operator $\mathcal{O}$. Explicitly we observe that there are a pair of exact solutions for the homogeneous case, $\mathcal{O}\psi_{1,2}=0$ given as the following
\begin{eqnarray}
\label{trial}&&\psi_1(x)=2\log (2|v+u|^{-1}),\ \ \psi_2(x)=2\log (2|v-u|^{-1}).
\end{eqnarray}
These solutions are found using a direct ansatz for the solutions $\psi\sim|u\pm v|^n$. After substituting into the field equation (\ref{kernel}), we find $n=-2$ for both cases $\psi_{1,2}$. The proportionality constant can be fitted after a more investigation of the homogeneous PDE. In the above solutions (whose are not the unique solutions because of the non linearity), the first $\psi_1$ is suitable for AdS boundary regimes $z\to 0$ while the second one works for non static cosmological AdS spacetime and suitable for regions with $z\to \infty$ (spatial boundary regions). Using the above pair of the "exact" modes we can show that the following symmetric preposition is a suggestion for Green function,
%how to typeset multi-part definitions in LaTeX.
\begin{eqnarray}
\label{green33}
G(x|x') =\left{ \begin{array}{ll} C \psi_1(u,v)\psi_2(u',v') Â & \mbox{if } u < u', v<v' \\ C \psi_1(u',v')\psi_2(u,v) & \mbox{if } u > u', v>v'
\end{array}\right.
\end{eqnarray}
We kept the expression for Green function in terms of any pair of exact modes, including the hypothetical solutions we presented in expressions (\ref{trial}). To fix the parameter $C$, one needs to integrate both sides of the inhomogeneous PDE (\ref{green1}). in a domain close to the singularity point, $x=x'$, we assume that the Green function remains continuous on the singularity, it provides the following limiting integral constraint via the mean value theorem in calculus,
\begin{eqnarray}&&
\lim {\epsilon_a\to 0}\int{v'-\epsilon_2}^{v'+\epsilon_2}dv\int {u'-\epsilon_1}^{u'+\epsilon_1} du \sqrt{g}=0.
\end{eqnarray}
The above integral denotes shrinking of the volume enclosed by the singularity point $x=x'$.
The other terms in the integration process can be calculated easily, after a simple usage of the Leibniz formula we obtain,
\begin{eqnarray}\label{green22}
&&\psi_1(u',v')\Big(\psi_2(u'+\epsilon_1,v'+\epsilon_2) -\psi_2(u'-\epsilon_1,v'+\epsilon_2)\Big)\&&\nonumber-\psi_2(u',v')\Big(\psi_1(u'+\epsilon_1,v'-\epsilon_2)-\psi_1(u'-\epsilon_1,v'-\epsilon_2)\Big)=-C^{-1}
\end{eqnarray}
We apply the Taylor series by assuming that $|\epsilon_a|\ll |x'|$, as the following,
\begin{eqnarray}
&&\psi_a(u'\pm \epsilon_1,v'\pm \epsilon_2)=\psi_a(u',v')\pm \epsilon_1\partial_u\psi_a|{u',v'}\pm \epsilon_2\partial_v\psi_a|{u',v'}+...
\end{eqnarray}
we simplify the (\ref{green22}) to the following,
\begin{eqnarray}
&&C=-\frac{\alpha'}{2W_u(\psi_1,\psi_2)|{u',v'}}
\end{eqnarray}
and we urge to redefine the deficit angle $\alpha'\equiv \frac{\alpha}{\epsilon_1}$. By inserting $C$ into the multi-part Green function (\ref{green33}) we finally obtain the metric function associate to the (\ref{problem}),
\begin{eqnarray}
&&\psi(x,x')=-\frac{\alpha'}{2W_u(\psi_1,\psi_2)|{u',v'}}\psi_1(u{<},v_{<})\psi_2(u_{>},v_{>})
\end{eqnarray}
here $x_{<},x_{>} $ refers to $x,x'$. A non trivial fully classical metric with deficit parameter can be written in the following explicit form
\begin{eqnarray}
&&ds^2=\exp{-\frac{\alpha'}{2W_u(\psi_1,\psi_2)|{u',v'}}\psi_1(u{<},v_{<})\psi_2(u_{>},v_{>})}dudv
\end{eqnarray}
Using the pair of the trial solutions (\ref{trial}) one can show that,
\begin{eqnarray}
&&W_u(\psi_1,\psi_2)=\psi_1\exp{\frac{\psi_2}{2}}+\psi_2\exp{\frac{\psi_1}{2}}
\end{eqnarray}
we end out with a smoothly (but with discontinuity at the singularity point) multi-part metric,%\psi_1(x)=2\log (2|v+u|^{-1}),\ \ \psi_1(x)=2\log (2|v-u|^{-1})%
\begin{eqnarray}
\label{green3}
ds^2 =dudv\left{ \begin{array}{ll}\exp{-\Big(\frac{\alpha(v'-u')}{2\epsilon_1\log(\frac{v'-u'}{v'+u'})}\Big)\log (2|v+u|^{-1})\log (2|v'-u'|^{-1})} Â & \mbox{if } u < u', v<v' \\\exp\{-\Big(\frac{\alpha(v'-u')}{2\epsilon_1\log(\frac{v'-u'}{v'+u'})}\Big) \log (2|v-u|^{-1})\log (2|v'+u'|^{-1})\} & \mbox{if } u > u', v>v' \end{array}\right.
\end{eqnarray}
The metric is continuous at boundary $x=x'$
\begin{eqnarray}
&&g^{>}{\mu\nu}|{x=x'}=g^{<}{\mu\nu}|{x=x'}.
\end{eqnarray}
but there is a discontinuity in the first derivative coming from the Green function ,
\begin{eqnarray}
&&\partial_{u}g^{>}{\mu\nu}|{x=x'}\neq \partial_{u}g^{<}{\mu\nu}|{x=x'}.
\end{eqnarray}
the last can be interpreted as a discontinuity in the affine connection for the spacetime. The reason is that the non vanishing components for the Christoffel symbol are given either as by $\partial_{u}\psi$ or $\partial_{v}\psi$. Note that the Green functions have discontinuity (or jumping) for both $\partial_{u,v}$. The discontinuity which is located at $\partial_{u}G(x|x')$ is proportional (more precisely equals) the Christoffel symbol $\Gamma^{t}_{\mu\nu}$. Any discontinuity in the $\Gamma$ will be transferred directly to the geodesics of the test particle. Basically we guess the trajectory of a test particle undergoes a critically.
A more interesting interpretation for the discontinuity will be presented in the nest section where we will address a phase transition between metrics which are representing the trial solutions $\psi_1,\psi_2$.
%%%%%%%%%%%%%%%%%%%%%
\section{More about the metrics associated to $\psi_1,\psi_2$ }\label{nonmini}
The trial solutions given in expressions (\ref{trial}) define two geometries with very interesting features,
\begin{eqnarray}&&
ds_1^2=\frac{4dudv}{(u+v)^2}, ,\&& ds_2^2=\frac{4dudv}{(v-u)^2}.
\end{eqnarray}
The Ricci scalar is $R=-2$ for both metrics except for asymptotic regions $u\to \pm v$ (conformal boundaries). If one write the metrics in the standard Poincare's coordinates, it represents a half plane metric for $z>0$. We mention here that any other solution except the AdS is a quotient $AdS/\Gamma$, here $\Gamma$ denotes a discrete subgroup of $SL(2,\mathcal{R})$ and as a result it is not unique solution.
It is instructive to rewrite the above metrics in the usual Poincare coordinates (not the Euclidean) where $u=z+i\tau,v=z-i\tau$,one immediately find that the metrics corresponding to the $\psi_1$ and $\psi_2$ are both represent $AdS_2$,
\begin{eqnarray}
&&ds_1^2=\frac{dz^2+d\tau^2}{z^2},\ \ AdS,\&& ds_2^2=-\frac{dz^2+d\tau^2}{\tau^2}, \ \ AdS.
\end{eqnarray}
The first can be interpreted as $AdS_2$ in the static path including the AdS boundary , the second one after a signature change represents non static patch of the AdS (if such patch existed at all). For the first metric, the dual system is supposed to lie on the conformal boundary $z=0$. Technically the conformal boundary locates at infinitely far away region.
The signature change from first to the second metric shows that the trial solutions belong to different metrics. That implies that, although the PDE for these functions is nonlinear but somehow "non linear" Independence of the solutions still remains valid. Although one can easily show that the AdS metric with wrong signature (signature changed) can be transformed to the AdS metric (both solutions are obtained as exact solutions for the homogeneous case with $\alpha=0$), if we let the metric coordinates $(z,\tau)$ undergo a complex conformal transformations ,
\begin{eqnarray}
&&(z\to i\tau, \tau\to z) \Longrightarrow (z\to iz, \tau\to\tau) \&&
ds_2^2=-\frac{dz^2+d\tau^2}{z^2}
\end{eqnarray}
The new metric is considered as the standard AdS which undergoes a signature change. Note that dJT gravity is diffeomorphism invariance as well as conformal invariance theory, i.e, any signature change of the metric $g_{\mu\nu}\to -g_{\mu\nu}$ doesn't change the action.
The reason is that under such transformation, the Ricci scalar remains unchanged because $R=g_{\mu\nu}R^{\mu\nu}\to R$. But signature change probably makes difference for the dilaton profile. Under such transformation, the dilaton probably will change.
\par
The signature change from static $AdS$ to the non static patch $AdS $, or equivalently from $ds_1^2\to ds_2^2$ can be understood by studying the trajectories of a test particle in the background of both metrics. For this purpose we have to write down the set of the equations of the motion (EoM) for trajectory, for simplicity we just consider a photon path, basically with a suitable parametrization, we can find the trajectories $(\tau(\zeta),z(\zeta))$ by minimization of the following string like actions,
\begin{eqnarray}
&&S_1=\pm \int\frac{d\zeta}{z}\sqrt{\dot{z}^2+\dot\tau^2},\ \ \mbox{for}\ \ Â ds_1^2,\&&S_2=\pm \int\frac{d\zeta}{\tau}\sqrt{\dot{z}^2+\dot\tau^2},\ \ \mbox{for}\ \ Â ds_2^2
\end{eqnarray}
for both action functionals there are a pair of the conserved charges, read as
\begin{eqnarray}
\label{es}
&&E_1=\frac{\dot\tau}{z\sqrt{\dot{z}^2+\dot\tau^2}},\ \ E_2=\frac{\dot z}{\tau \sqrt{\dot{z}^2+\dot\tau^2}}
\end{eqnarray}
Here $E_1$ has the meaning of an energy while $E_2$ defines a conserved transnational momentum along the $z$ coordinate.
one can easily show that the above first integrals are the unique EoMs for the trajectories , the second EoM trivially satisfied. By using the conserved charges (\ref{es}), we can show that the trajectory of the test particle reduces to the existed points on the Hamilton surface (first integral),
\begin{eqnarray}
&& \tau^2-(\frac{E_1}{E_2})z^2=b
\end{eqnarray}
here $b$ is constant. Depending on the sign of this parameter, we have the following cases,
\begin{itemize}
\item If $b>0,\frac{E_1}{E_2}<0$, then the trajectory is either an elliptic (for $E_1\neq E_2$ ) or circular (for  $E_1= E_2$ ). The trajectory corresponds to non static patch of the AdS.
\item If $b\geq 0,\frac{E_1}{E_2}>0$, then the trajectory is either a hyperbolic  (for $E_1\neq E_2$ ) or line (for  $E_1= E_2,b=0$ ), its simply the typical trajectory in static patch of the AdS.
\item For $b<0$, one can show that the situation remains the same as the above cases if one performs the coordinates transformations as $\tau\to z\sqrt{|\frac{E_1}{E_2}|} $.
\end{itemize}
The signature change can be understood as a change in the photon trajectory from static region in the AdS to non static (cosmological) patch adequately. If the conserved charges have different signatures , then the trajectory is closed, it corresponds to $AdS$ as a possibility to have minimal surfaces in hyperbolic spaces with negative curvature (that is AdS). For the case when the conserved changes have different signs, the particle trajectory falls down into non static patch (or equivalently into an open dS universe) , there is no minimal surface that corresponds to the non static patch of the AdS. We can understand the transition from AdS to AdS as a phase transition. It corresponds to the Green function we obtained . Indeed as we know, the derivative of the Green function has a jump discontinuity at $x=x'$. This type of discontinuity is interpreted as a discontinuity in the first derivative of the metric or more precisely the Christoffel symbols. Let us explain it in a more concrete way: The Green function as the response function of the inhomogeneous Witten's equation is dual to the two point function of a boundary operator $\hat{O}$. In our case it is related to the probability of measuring a field $\phi(x)$ when the source is at $x'$. A discontinuity in the metric function implies a jumping in the free energy of the system. It is known that the free energy can be written in terms of the thermal Green functions for a bulk/boundary theory. Remembering that the Green functions is the two point correlation function and expectation value of the operators can be expressed in terms of the partition function using the path integrals. We postulate that the following discontinuity in the metric for a non zero deficit parameter $\alpha$ addresses the phase transition from static to cosmological patch of the AdS in dJT at least in a formal form. For a better understanding of the phase transition one should compare the free energy for bulk theory in dJT for different patches of the AdS. We guess that a more careful calculation will support the argument which we stated here .
%%%%%%%%%%%%%%%%%%%%%%
\section{Black hole solutions }
The Green function metric derived in the previous section and it's interesting phase transition scenario can be recast into a spherically symmetric Euclidean metric in the Schwarzschild coordinates $x^{\mu}=(t,r)$. As we learned from study of the exact solutions in the null coordinates ,to define the metric for the geometry we need to specify only one gauge function here could be function of $(r)$ as the following,
\begin{eqnarray}
&&ds^2=A(r)dt^2+\frac{dr^2}{A(r)}\label{metric22}
\end{eqnarray}
Any other representation of the metric with two arbitrary functions, for example $A(r),B(r)$ can be recast to the above case after a suitable reparametrization of the radial(spatial) coordinate $r$. For the case of time dependent metric it is very difficult to reduce the metric to the null coordinates form or eliminate one of the metrics functions. A reason is that one can't deduce a simple Birkhoff's theorem for JT gravity. It is very hard to prove that the JT gravity posses only static and asymptotically flat solutions in the absence of any other matter field contents. We don't study the validity of such fundamental theorem in the JT gravity as also we are not sure about such proof in more general cases of the UV free two dimensional theories for quantum gravity. \par
If we limit our study to the case where metric remains time independent, it is easy to show that for non singular case , i.e, when $\alpha=0$, the classical field equations provides a class of the exact solutions for the metric found in \cite{Witten:2020ert}. Furthermore for a general class of the deformation potentials $U(\phi)$, the metric function given by
\begin{eqnarray}
&&A(r)=\int_{r_h}^{r}U(r')dr'
\end{eqnarray}
in the above suggested solution, we supposed that there exists a blackhole solution with a null hyperbolic surface (horizon) which is located at $r=r_h$ and $A(r_h)=0$. The value of the dilaton field $\phi(r_h)=\phi_h$ kept finite and positive. One can show that the near horizon geometry of the metric is thermal region with the temperature given by
\begin{eqnarray}
&&T=\frac{U(\phi_h)}{4\pi}
\end{eqnarray}
If one try to satisfy the JT gravity asymptotically bound on the potentail function $U(\phi)$ defined in expression (\ref{delta}), we can show that the asymptotic form for the metric at the limit $\phi\to \infty$ is
\begin{eqnarray}
&&A(r)=r^2-b+\mathcal{O}(r^{-\delta })
\end{eqnarray}
Using simple arguments, one can show that the first law of the thermodynamics still holds if one identify the parameter $b$ as a quasi energy $E=\frac{b}{2}$ defined via the Gibbons-Hawking-York surface.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\par
Our aim in this section is to find
an exact solution for the Witten's equation (\ref{problem}) with a single deficit angle with metric form given by (\ref{metric22}). A remarkable observation is that the metric keeps the Dirac function same as the flat Euclidean metric. That is because the metric is uni-modular i.e, $\det{g_{\mu\nu}}=1$,the normalization condition for Dirac delta function
\begin{eqnarray}
&&\int \sqrt{g(x_1)}d^2x_1 \delta(x_1-x_2)=\int_{M^2} dr dt \delta(r-r')\delta(t-t')=1
\end{eqnarray}
Using the spherical symmetry of the metric one can
write the Dirac delta function only as a $r$ dependent form
\begin{eqnarray}
&&\delta(x-x')=\delta(r-r')
\end{eqnarray}
where we implied the time Independence of the metric as well as spherical symmetry. Using the metric,
we can compute the Ricci scalar as $R=-A''$, the equation for the modular space reduces to the following linear ODE:
\begin{eqnarray}\label{ODEA}
&&A''=2(1-\alpha \delta(r-r')),\ \ \alpha\neq 0.
\end{eqnarray}
for single deficit parameter $\alpha$, and a single conical singularity located at $r=r'$. An exact solution for the metric can be obtained using simple integration techniques,
\begin{eqnarray}
&&A(r)=r^2 + c_1 + r c_2 - 2 \alpha (r-r') \theta(r-r').\label{A1}
\end{eqnarray}
here $\theta(x)$ is the Heaviside theta (step function),
\begin{eqnarray}
\label{green33}
\theta(r-r') =\left{ \begin{array}{ll} 0 Â & \mbox{if } r<r' \\ 1 & \mbox{if } r>r'
\end{array}\right.
\end{eqnarray}
One can directly show that the above metric function solves ODE given in eq. (\ref{ODEA}), because as we know $(x-x')\delta(x-x')=0$, as a result $2 \delta(x-x')+(x-x')\frac{d\delta(x-x')}{dx}\equiv \delta(x-x')$. The metric explicitly written as
\begin{eqnarray}
ds^2=\left{ \begin{array}{ll} (r^2 + c_1 + r c_2)dt^2+\frac{dr^2}{r^2 + c_1 + r c_2} Â & \mbox{if } r<r' \\ (r^2 + c_1 + r c_2-2\alpha(r-r'))dt^2+\frac{dr^2}{r^2 + c_1 + r c_2-2\alpha(r-r')} & \mbox{if } r>r'
\end{array}\right.
\end{eqnarray}
The metric suffered from a first jumping singularity at $r=r'$, where the metric radial derivative $\partial_r g_{\mu\nu}|_{r=r'-0}\neq \partial_r g_{\mu\nu}|_{r=r'+0}$. It can be interpreted as a discontinuity in the connections. For the exterior region $r>r'$, we observe that if we apply the following transformation to the metric within the interior region $rr'}$ will be mapped to the one on the exterior region,
\begin{eqnarray}
&&c_1\to c_1+2\alpha r',\ \ c_2\to c_2-2\alpha
\end{eqnarray}
consequently we deduce that the exterior metric can be mapped analytically to the interior metric as the following
\begin{eqnarray}
&&ds^2(r<r')_{\Big[c_1\to c_1+2\alpha r',\ \ c_2\to c_2-2\alpha \Big]}\longrightarrow ds^2(r>r')
\end{eqnarray}
The singularity sphere with equation $r=r'$ can be identified only with a unique metric for inner or outer regions.
\par
The metric function has the following regular form for both regions but with different values of the metric parameters $(c_1,c_2)$
\begin{eqnarray}
&&g_{tt}=g_{rr}^{-1}=r^2 + c_1 + r c_2
\end{eqnarray}
The metric can be considered as a blackhole with horizon radius $r_h$
\begin{eqnarray}
&&r_h=\frac{1}{2}(-c_2+\sqrt{c_2^2-4c_1}), \ \ c_1<0,c_2>0.
\end{eqnarray}
The second root of the equation $g_{tt}(r)=0$ is negative and completely will be removed from further considerations. Note that one can study near horizon geometry , we have
\begin{eqnarray}
&&A(r)=\sqrt{c_2^2-4c_1}(r-r_h)+\mathcal{O}((r-r_h)^2)
\end{eqnarray}
We define a new coordinate $z=r-r_h$, using this coordinate the near horizon geometry represented as the following,
\begin{eqnarray}
&&ds^2\approx \frac{4}{\sqrt{c_2^2-4c_1}}\Big(dz^2+(\frac{c_2^2-4c_1}{4}) z^2dt^2
\Big)
\end{eqnarray}
The metric remains smooth in the vicinity of the $z=0$, if and only if
\begin{eqnarray}
&&t\cong t+\frac{4\pi}{\sqrt{c_2^2-4c_1}}
\end{eqnarray}
It defined the temperature as $T=\frac{\sqrt{c_2^2-4c_1}}{4\pi}$.

%%%%%%%%%%%%%%%%%%%%%%%%%
\par
For the case with the deficit parameters more than one, when $\alpha_{I}\equiv (\alpha_1,\alpha_2,..,\alpha_k)$ and using the metric form as we used in the case with a single deficit parameter $\alpha$,
the Witten's equation for the deformed hyperbolic geometry changes to the following form,
\begin{eqnarray}
&&A''=2(1-\sum_{i=1}^{k}\alpha_i\delta^{(2)}(x-x'i)).
\end{eqnarray}
We are lucky to have a linear ODE, using the superposition principle
, exact solution for a set of the deficit parameters and singularities can be obtained using the general solution which we obtained for the singular parameter i.e, eq. (\ref{A1}),
as $A_{k}(r)=\sum_{i=1}^k A_i$ where
\begin{eqnarray}
&&A_i= \frac{r^2}{k}+ c{i}^{(1)} + rc_{i}^{(2)} - 2\alpha_i(r-r'i) \theta(r-r'_i)
\end{eqnarray}
The general metric solution for $\mathcal{M}_{g,k}$ is
\begin{eqnarray}
&&A{k}(r)= r^2+\sum_{i=1}^{k}\Big( c_{i}^{(1)} + rc_{i}^{(2)} + 2\alpha_i(r'i-r) \theta(r-r'_i)\Big).
\end{eqnarray}
It can be understood as a superposition of the single mode solutions as one of the rare cases where the Einstein gravity still respects superposition principle. The metric explicitly written as
\begin{eqnarray}
ds{k}^2=\left{ \begin{array}{ll} ( r^2+\sum_{i=1}^{k}\Big( c_{i}^{(1)} + rc_{i}^{(2)} \Big) )dt^2+\frac{dr^2}{ r^2+\sum_{i=1}^{k}\Big( c_{i}^{(1)} + rc_{i}^{(2)}\Big)} ‚ & \mbox{if } r<r' \\ <br />( r^2+\sum_{i=1}^{k}\Big( c_{i}^{(1)} + rc_{i}^{(2)} + 2\alpha_i(r'_i-r) \Big) )dt^2+\frac{dr^2}{ r^2+\sum_{i=1}^{k}\Big( c_{i}^{(1)} + rc_{i}^{(2)} + 2\alpha_i(r'_i-r) \Big) } & \mbox{if } r>r'
\end{array}\right.
\end{eqnarray}
In the above metric, the set of the integration parameters
\begin{eqnarray}
&&c_{i}^{(1)}\to c_{i}^{(1)}+2\alpha r',\ \ c_{i}^{(2)}\to c_{i}^{(2)}-2\alpha
\end{eqnarray}
under the following transformations the metrics for interior and exterior regions remains unaltered,
\begin{eqnarray}
&&ds_{k}^2(r<r')_{\Big[c_{i}^{(1)}\to c_{i}^{(1)}+2\alpha_i r',\ \ c_{i}^{(2)}\to c_{i}^{(2)}-2\alpha_i \Big]}\longrightarrow ds_{k}^2(r>r')
\end{eqnarray}
The near horizon geometry and temperature can be recovered as we obtained in the case with a single deficit parameter only if we replace $c_1,c_2$ as the following,
\begin{eqnarray}
&&c_1\to \sum_{i=1}^{k}c_{i}^{(1)},
\ \ c_2\to \sum_{i=1}^{k}c_{i}^{(2)}.
\end{eqnarray}
The temperature for the case with many finite deficit parameters can be written as the following expression,
\begin{eqnarray}
&&T=\frac{\sum_{i,j=1}^{k}c_{i}^{(2)}c_{j}^{(2)}-4\sum_{i=1}^{k}c_{i}^{(1)}}{4\pi}
\end{eqnarray}
where we assumed that $\sum_{i=1}^{k}c_{i}^{(1)}<0$.
%%%%%%%%%%%%%%%%%
\section{On singular manifold with time-dependent metrics }
In the previous section we investigated exact blackhole solutions when the metric considered as time independent, i.e, when $A=A(r)$. Under this assumption we integrate a linear ODE with Dirac delta source term and the analysis could be extended to the situation when the deficit parameters $\alpha_i$ be more than one but still remains finite. In this section we want to see if we relax the constraint of time independence and allow the metric to be time dependent, how the singular surfaces will be deformed adequately. Firstly we note that although in two dimensions it is possible to reduce the metric to a conformal flat Euclidean metric in general, but when the metric is considered time dependent,
\begin{eqnarray}
&&ds^2=g_{tt}(t,r)dt^2+2g_{tr}(t,r)dtdr+g_{rr}(t,r)dr^2
\end{eqnarray}
the metric can't not be written as a conformal flat form. Let us see what is going to happen if one factorize the above arbitrary time dependent metric,
\begin{eqnarray}
&&ds^2=g_{tt}(t,r)\Big(dt+A_{r}(t,r)dr
\Big)^2+\Big(g_{rr}(t,r)-\frac{g_{tr}(t,r)^2}{g_{tt}(t,r)}\Big)dr^2
\end{eqnarray}
where the non static vector potential (or angular velocity in the terminology of the lower dimensional blackholes) is defined as $A_{r}(t,r)\equiv \frac{g_{tr}(t,r)}{g_{tt}(t,r)}$. If one needs a conformal flat form of the above metric, we are requested to find a set of the new coordinates $T,R$ such that ,
\begin{eqnarray}
&&dT(t,r)=dt+A_{r}(t,r)dr\label{eqT}
\&&
dR(t,r)=\sqrt{g_{rr}(t,r)-\frac{g_{tr}(t,r)^2}{g_{tt}(t,r)}}dr\label{eqR1}
\end{eqnarray}
The first equation is not a regular Pfaffian form. Let us try to make it Pfaffian using an auxiliary function $\mu(t,r)$, where
\begin{eqnarray}
&&\frac{\partial \mu(t,r)}{\partial r}=\frac{\partial \Big(\mu(t,r)A_{r}(t,r)\Big)}{\partial t}
\end{eqnarray}
The aim is to find at least one auxiliary function $\mu(t,r)$ to make (\ref{eqT}) a Pfaffian form and makes us possible to integrate (\ref{eqR1}). After a carefully investigation, we see that the following cases are possible:
\begin{itemize}
\item $\mu(t,r)=\mu(t)$: Following this constraint we obtain $\mu(t)A_{r}(t,r)=C(r)$ and finally it suggests that $\mu(t)=\frac{C(r)}{A_{r}(t,r)}$. The only possibility is when $A_{r}(t,r)=A_1(r)A_{2}(t)$. With this choice of the vector potential, we can show that
\begin{eqnarray}
&&\frac{g_{tr}(t,r)}{g_{tt}(t,r)}=\frac{C(r)}{A_1(r)A_{2}(t)}=\frac{\tilde{C}(r)}{A_2(t)}
\end{eqnarray}
under these constraints, the first (\ref{eqT}) converts to a Pfaffian form ,
\begin{eqnarray}
&&dT(t,r)=\mu(t)dt+C(r)dr=d\Phi(t,r)
\end{eqnarray}
where the potential function
\begin{eqnarray}
&&\Phi(t,r)=\tilde{C}(r)\int \frac{dt} {A_{2}(t)} +\int dr C(r)
\end{eqnarray}
then the second integral gives us
\begin{eqnarray}
&&
dR(t,r)=dr\sqrt{g_{rr}(t,r)-(\frac{\tilde{C}(r)}{A_2(t)})^2g_{tt}(t,r)}\label{eqR}
\end{eqnarray}
the above differential form can be integrated only if $g_{rr}(t,r)-(\frac{\tilde{C}(r)}{A_2(t)})^2g_{tt}(t,r)=B(r)$. Using the above set of the new coordinates $T,R$, the metric reduces to a conformal flat form after defining a set of the null coordinates $U,V$ adequately(see for example \cite{Momeni:2020zkx}).

\item $\mu(t,r)=\mu(r)$: In this situation, the factor $\mu(r)$ can be obtained as
  \begin{eqnarray}

&&\mu(r)=\exp{\frac{\partial }{\partial t}}\int dr A_{r}(t,r)
\end{eqnarray}
it becomes meaningful if and only if $A_{r}(t,r)\propto t $. Within this condition we obtain $\mu(r)=\exp{\int dr A_{r}(r)}$. This case is also provides set of the appropriate null coordinates. But as we checked , in general one can't reduce any two dimensional metric to a flat conformal form.
\end{itemize}
In dJT, the singular surfaces with time dependent metric are completely different from the static ones. Let us simple consider a very restricted form of such metrics when the metric is given by a single gauge $A(t,r)=g_{tt}=g_{rr}^{-1},\ \ g_{tr}=0.$ Even if we consider the case with one deficit parameter $\alpha$, the Witten's equation for the singular metrics reduces to a nonlinear second order PDE, with a source term as $\delta(r-r')\delta(t-t')$. The model can be considered as a nonlinear wave equation in an inhomogeneous medium. There won't be an easy exact solution for the metric function $A(t,r)$, that means one can't construct (easily) an analytic Green function for such wave equation in such an inhomogeneous medium. A further study can be done if we provide an appropriate set of the initial conditions for the Green function and integrate numerically the Green function very carefully in the vicinity of the singularity point. Otherwise , we have to find Green function perturbative , order by order if any dimensionless perturbation parameter can be found in the model

%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%
\section{Conclusion}
In this work, we investigated deformed geometries for deformed JT gravity recently proposed by E.\,Witten \cite{Witten:2020ert}. As claimed by Witten, there should not be any type of classical geometry for deficit angle $\alpha>2\pi$ . We found a class of metric solutions in the null coordinate as a non trivial solution for the nonlinear PDE formulated as Witten's problem. The metric  expressed as the Green function for the operator. There is a discontinuity in the metric derivative and that implies a type of the phase transition between AdS and AdS metrics. Although Witten's equation for the deformed hypersurface with $\alpha\neq 0$ is nonlinear, we demonstrated that some linear independence still remains in theory. As an attempt to prove the difference between two independent exact solutions to the homogeneous equation, we studied the null geodesics of two metrics. It has been shown that the trajectory of the test particle coincides with the classical trajectories in two different patches of the AdS. Although we didn't compute the free energy, a qualitative discussion provides more evidence about a coexistence phase of both patches of the AdS in dJT. It will be very interesting to compare such formal phase transition with the realistic description which has been investigated in the details is Re. \cite{Witten:2020ert}. The thermodynamical phase transition proposed for dJT in the above reference is based on the study of the free energy of a given exact dilatonic blackhole obtained in a suitable scale invariant (gauge fixed) Euclidean form for the metric. In our study a pair of the patches for the AdS spacetime are surprisingly appeared in the model as exact solutions (with a signature change) to the homogeneous Green equation. The phase transition from static patch of the Ads to non static one which we proposed in our work can be interpreted as a simple phase transition from an Euclidean AdS to another Euclidean AdS along a signature change.e,
\begin{eqnarray}
&&AdS\Longrightarrow_{Signature-changed } AdS
\end{eqnarray}
Because the signature change in the Euclidean (or even Lorentzian) metrics usually occurs when we pass a horizon (or getting close to the singularity), the phenomena here looks a bit odd and we have to study it in more details in out forthcoming work(s). One possible description could be as the following: small quantum fluctuations in the dJT could makes a clouds surrounding the AdS blackhole. Although it can't make a horizon , it is possible to make a transitive horizon with very short life time. Consequently the metric in the outer region of the cloud described by the usual Euclidean AdS while one passes the temporal cloudy horizon, the metric signature eventually changes.
We mention here that the phase transition described in a purely classical sense using the classical trajectories. We expanded our study by considering blackhole solutions in theory with a single and finite number of the deficit parameters $\alpha$. In the case of the single parameter we found a class of exact static, spherically symmetric two dimensional blackhole solutions with a non zero temperature and a well behaviour horizon. We show that the metric for the  exterior region $r>r'$ beyond the singularity point $r=r'$ can be mapped smoothly to the interior metric within the region $r

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\end{thebibliography}

\end{document}

Speaker: Davood Momeni (Sultan Qaboos University)

18:30 Magnetic field from sphaleron decay and bubble collisions

We have performed three dimensional lattice simulations of the magnetic field production during the process of the first-order electroweak phase transition. We show that the magnetic field production can come from sphaleron decay and bubble collisions together, with the former dominates the magnetic field generation process at the first beginning of the bubble nucleation, and the latter dominates the magnetic field production at the stage of the vacuum bubbles accelerating expansion and coalescence. This study can serve as a probe of the bubble wall velocity that is crucial for the baryon asymmetry explanation of the Universe and the gravitational wave production from the first-order phase transition, and also serve as an approach to probe the sphaleron process indirectly. The magnetic field spectrum shows a double peak shape with the increase of the bubble wall thickness.

Speaker: Ligong Bian