PIKIMO 12

Saturday 30 Apr 2022, 09:00 → 17:30 America/New_York

PIKIMO 12

The High Energy Physics group at the University of Notre Dame is excited to host the 12th PIKIMO meeting on Saturday, April 30th, 2022. The meeting will be conducted in a hybrid format, with both an in-person attendance option at the University of Notre Dame and a remote attendance option over Zoom.  

PIKIMO 12 will bring together particle theorists and experimentalists from universities that are part of the PIKIMO group. We strongly encourage in-person attendance at the meeting.

All in-person attendees are required to be vaccinated. The meeting will take place at 205/206/207 McKenna Hall.

Keynote Speakers:

• Kimberly Boddy (U.Texas, Austin)
• Patrick J. Fox (Fermilab)

To participate, please register for the meeting. There you can indicate your plans to attend the meeting either in-person or remotely. If you wish to present a talk at the meeting, please submit an abstract.

 

Pikimo12-Digital-Poster.jpg

Pikimo12-Print-8x11-w-QRCode.pdf

09:00 → 09:30 Breakfast + Introduction

09:30 → 10:45 Morning Session

09:30 Searching for Lorentz violation and spin-gravity couplings in experiments

Lorentz violation has been a popular topic in recent years. We studied the linearized limits of the generic Lorentz-violating terms in curved spacetime and applied them to gravitational experiments. Three types of experiments, free-dropping, gravitational interferometer, and gravitational bound-state experiments, are studied. First constraints on certain new coefficients for Lorentz violation and spin-gravity couplings are extracted from them.

Speaker: Zonghao Li

Zonghao_Li_PIKIMO12.pdf

Zonghao_Li_PIKIMO12.pptx

09:45 Chirally-Enhanced Muon g-2 and Its Implications to Higgs-Related Observables

I introduce extensions of the Standard Model and a two-Higgs-doublet model with vectorlike leptons which generate chirally-enhanced contributions to the muon's anomalous magnetic moment, $(g-2)_{\mu}$. I show an additional $\tan^2\beta$ enhancement in the Higgs sector can generate up to two-orders of magnitude larger contributions to the magnetic moment while satisfying relavant constraints. These enhanced contributions can clearly explain the anomaly within $1\sigma$ for new lepton and Higgs masses up to tens of TeV, despite this heavy scale being currently unreachable at the LHC. Finally, I demonstrate a connection between a single parameter and $(g-2)_{\mu}$, $h \rightarrow \mu^{+} \mu^{-}$, $\mu^{+} \mu^{-} \rightarrow h h$ and $\mu^{+} \mu^{-} \rightarrow h h h$ observables, suggesting that $(g-2)_{\mu}$ can uniquely determine these Higgs-related processes.

Speaker: Keith Hermanek

Hermanek_PIKIMO_talk.pdf

10:00 Searching for Ultralight Dark Matter with Light

Ultralight dark matter (UDM) is a well motivated dark matter candidate. However, direct detection of UDM poses an experimental challenge due to the low energy scales and weak couplings involved. We propose to use optical microring resonators to search for UDM particles. The microring resonators not only have a high quality factor which produce large enhancements in signal power, but also can be made from non-linear dielectric materials which enable novel search channels. We study the sensitivity of microring resonator based searches to axion dark matter and dark photon dark matter sub-eV scale.

Speaker: Christina Gao

Gao_pikimo_microring.pdf

10:15 Cosmological Dark Photon Oscillations in Non-Minimal Dark Sectors

As many of us know, the cosmic microwave background has a black-body spectrum. This is confirmed by COBE-FIRAS data three decades ago with exact measurement and tiny error bars.

However, the existence of new physics, such as the photon-dark photon oscillation with non-zero kinetic mixing, will distort the black body spectrum. Based on this character, and the fact that the deviation of CMB from the black body spectrum is highly constrained, we can give strict constraints on the new physics, for example, the dark photon parameter space.

In our work, we extend the discussion to the non-minimal dark sector and strongly constrain the millicharged particles(MCPs) parameter space. We will also discuss how the existence of MCPs will change the FIRAS bound of the minimal dark photon model.

Speaker: Mr Xucheng Gan (New York University)

PIKIMO12_XG_Pre.pdf

10:30 Searching for Dark Matter with SRF Cavities

Advancements in superconducting radio-frequency (SRF) cavity design have the potential to enable searches for beyond the Standard Model physics with weak coupling to photons. To motivate the use of SRF cavities as particle detectors, we will discuss the generic properties of these cavities in the context of detecting small photon couplings. Next, we will describe the application of SRF cavity searches to two dark matter models, axion-like particles (ALPs) and primordial black holes (PBHs). Examining the resonant sensitivity of a single cavity to ALP-mediated light-by-light scattering, we will show that with feasible cavity parameters, future experiments can probe previously unexplored ALP parameter space. We will then discuss the potential for indirect detection of PBHs using cavities as gravitational wave detectors. We argue that for models of PBHs which favor inspirals, PBH mergers can emit gravitational waves that are potentially detectable by future SRF cavity experiments.

Speaker: Michael Wentzel

pikimo-wentzel.ppsx

pikimo-wentzel.pptx

10:45 → 11:15 Break

11:15 → 12:30 Noon Session

11:15 Cosmologically Degenerate Fermions

Even in the total absence of thermal kinetic energy, fermionic dark matter must have nonzero momentum due to the Pauli degeneracy pressure. As the fermions were inevitably denser at higher redshifts, a typical fermion may gain a fermi momentum that can exceed its mass. I will talk about the impacts of the transition between nonrelativistic and relativistic behaviour, as revealed by measurements of DNeff and the matter power spectrum. Minimal fermion mass bound will be presented, for a given fraction of the dark matter energy density the fermionic dark matter is occupying. I will also remark on implications for direct detection and suggest models of dark sectors that may give rise to cosmologically degenerate fermions.

Speaker: Ms Ying-Ying Li (Fermilab)

CosmologicallyDegenerateFermion.pdf

11:30 Maximizing Direct Detection with HYPER Dark Matter

We estimate the maximum direct detection cross section for sub-GeV dark matter scattering off nucleons. For dark matter masses in the range of $10 \text{ keV} − 100 \text{ MeV}$, cross sections greater than $10^{−36} - 10^{−30} \text{ cm}^2$ seem implausible. We introduce a dark matter candidate which realizes this
maximum cross section: HighlY interactive ParticlE Relics (HYPERs). After HYPERs freeze-in, a dark sector phase transition decreases the mass of the mediator which connects HYPERs to the visible sector. This increases the HYPER’s direct detection cross section, but in such a way as to leave the HYPER’s abundance unaffected and avoid conflict with measurements of Big Bang Nucleosynthesis and the Cosmic Microwave Background. HYPERs present a benchmark for direct detection experiments in a parameter space with few known dark matter models.

Speaker: Robert McGehee

slides.pdf

11:45 Signatures of hidden dark sectors

While particle dark matter is often modeled or presented as being a single species of matter, it is possible that dark matter is a part of a larger dark sector that may contain additional dark particles and dark forces. Such a scenario gives rise to rich phenomenology and can have a significant impact on astrophysical and cosmological observables. Furthermore, if the dark sector is secluded from the visible sector, gravitational probes become the only means to study the nature dark matter. In this talk, I will discuss some of the observational signatures of minimal dark sectors that feature dark matter self-interactions through the exchange of a light mediator.

Speaker: Kimberly Boddy (University of Texas at Austin)

kboddy-PIMIKO.pdf

12:30 → 14:00 Lunch

14:00 → 15:45 Afternoon Session

14:00 Looking for Dark Matter in Novel Ways

To date dark matter has only revealed itself to us through its gravitational interactions, despite our best efforts to see more direct signals. The increasingly strong constraints on WIMP-like dark matter have led to a proliferation of new models of dark matter. These new models present both challenges and opportunities for discovery of the dark sector. I will present a few examples of dark sector model building and a few of the new ways one can search for this elusive beyond the standard model physics.

Speaker: Patrick James Fox

PIKIMO2022.pdf

14:45 A Cosmological Lithium Solution from Discrete Gauged Baryon Minus Lepton Number

We propose the infrared gauge symmetry of our sector includes an unbroken discrete gauged subgroup of baryon minus lepton number of order 2 x 3 colors x 3 generations = 18, the inclusion of which does not modify local physics. We UV complete this at Λ as the familiar U(1)_{B-NcL} Abelian Higgs theory, and the early universe phase transition forms cosmic strings which are charged under an emergent higher-form gauge symmetry. These topological defects catalyze interactions which turn 3 baryons into 3 leptons at strong scale rates in an analogue of the Callan-Rubakov effect.

The cosmological lithium problem---that the observed primordial abundance is lower than theoretical expectations by a factor of a few---is perhaps the most statistically significant anomaly of SM+ΛCDM, and has resisted decades of attempts by cosmologists, nuclear physicists, and astronomers alike to root out systematics. We write down a model in which B-NcL strings superconduct bosonic global baryon plus lepton currents and catalyze solely 3p+ → 3e+. We suggest that such cosmic strings have disintegrated O(1) of the lithium nuclei formed during Big Bang Nucleosynthesis and estimate the rate, with our benchmark model finding Λ∼10^8 GeV gives the right number density of strings.

Speaker: Seth Koren

15:00 New constraints on extended Higgs sectors from the trilinear Higgs coupling

The trilinear Higgs coupling λhhh is crucial for determining the structure of the Higgs potential and for probing possible effects of physics beyond the Standard Model (SM). Focusing on the Two-Higgs-Doublet Model as a concrete example, we identify parameter regions in which λhhh is significantly enhanced with respect to the SM. Taking into account all relevant corrections up to the two-loop level, we show that already current experimental bounds on λhhh rule out significant parts of the parameter space that would otherwise be unconstrained. We illustrate the interpretation of the results on λhhh for a benchmark scenario. Similar results are expected for wide classes of models with extended Higgs sectors.

Speaker: Henning Bahl

2022_04_30_PIKIMO_meeting.pdf

15:15 Amplitude/Operator Basis from Mathematica

We established a framework to generate the full operator basis for all kinds of effective field theories, including the Standard Model Effective Field Theory and Chiral Perturbation Theories. The construction is based on the correspondence between operators and local on-shell amplitudes. Conversions among various bases are made possible. In this talk, I am going to show the code implementation of these functions using the Mathematica package ABC4EFT.

Speaker: Minglei Xiao

amp_op_basis_mma.pdf

15:30 High-quality axions in solutions to the $\mu$ problem

Solutions to the $\mu$ problem in supersymmetry based on the Kim-Nilles mechanism naturally feature a Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) axion with decay constant of order the geometric mean of the Planck and TeV scales, consistent with astrophysical limits. We investigate minimal models of this type with two gauge-singlet fields that break a Peccei-Quinn symmetry, and extensions with extra vectorlike quark and lepton supermultiplets consistent with gauge coupling unification. We show that there are many anomaly-free discrete symmetries, depending on the vectorlike matter content, that protect the Peccei-Quinn symmetry to sufficiently high order to solve the strong CP problem. We study the axion couplings in this class of models. Models of this type that are automatically free of the domain wall problem require at least one pair of strongly interacting vectorlike multiplets with mass at the intermediate scale, and predict axion couplings that are greatly enhanced compared to the minimal supersymmetric DFSZ models, putting them within reach of proposed axion searches.

Speaker: Prudhvi Bhattiprolu (University of Michigan)

pbhattiprolu.pdf

15:45 → 16:15 Break

16:15 → 17:30 Evening Session

16:15 Thermal Dark Matter and Primordial Black Holes

It is quite conceivable that cosmology may give rise to appreciable populations of both particle dark matter and primordial black holes (PBH) with the combined mass density providing the observationally inferred value $\Omega_{\rm DM} \approx 0.26$. However, previous studies have highlighted that scenarios with both particle dark matter and PBH are strongly excluded γ-ray limits assuming particle dark matter with a velocity independent thermal cross section $\langle\sigma v\rangle\sim 3 \times 10^{-26}{\rm cm}^3/{\rm s}$, as is the case for classic WIMP dark matter. Here we extend these existing studies on s-wave annihilating particle dark matter to ascertain the limits from diffuse γ-rays on velocity dependent annihilations which are p-wave with $\langle\sigma v\rangle\propto v^{2}$ or d-wave with $\langle\sigma v\rangle\propto v^{4}$. Furthermore, we highlight that even if the freeze-out process is p-wave it is relatively common for (loop/phase-space) suppressed s-wave processes to actually provide the leading contributions to the experimentally constrained γ-ray flux from the PBH halo.

Speaker: Mr Prolay Chanda (University of Illinois Chicago)

Talk-PBH.pdf

16:30 The phenomenological cornucopia of SU(3) exotica

We catalog the gauge-invariant interactions of Standard Model particles and new fields in the six-dimensional (sextet, $\boldsymbol{6}$) representation of the SM color gauge group $\mathrm{SU}(3)_{\text{c}}$. We consider effective operators of mass dimension up to seven, featuring both scalar and fermionic color sextets. We use an iterative tensor-product method to identify the color invariants underpinning such operators, emphasizing structures that have received little attention to date. In order to demonstrate the utility of our approach, we study a simple but novel model of color-sextet fields at the LHC. We compute cross sections for an array of new production channels enabled by our operators, including single-sextet production and sextet production in association with photons or leptons. We also discuss dijet-resonance constraints on a sextet fermion. This example shows that there remains a wide array of fairly minimal but well motivated and unexplored models with extended strong sectors as we await the high-luminosity LHC.

Speaker: Taylor Murphy

PIKIMO_12_Murphy.pdf

16:45 Underdamped Axionic Blue Isocurvature Perturbations

Previous computations of strongly blue tilted axionic isocurvature spectra were computed in the parametric region in which the lightest time-dependent mass is smaller than the Hubble expansion rate during inflation, leading to an overdamped time evolution. Here we present the strongly blue tilted axionic isocurvature spectrum in an underdamped time evolution parametric regime. Somewhat surprisingly, there exist parametric regions with a strong resonant spectral behavior that leads to rich isocurvature spectral shapes and large amplitude enhancements. We focus on computing this resonant spectrum analytically in parametric regions amenable to such computations. Because the spectrum is sensitive to nonperturbative classical field dynamics, we will discuss a wide variety of analytic techniques that are used like decoupling, nonlinear field redefinition, a time-space effective potential obtained by integrating out high-frequency fluctuations, and a piecewise mass-model.

Speaker: SAI CHAITANYA TADEPALLI

Conf_talk_PIKIMO_2022.pdf

Conf_talk_PIKIMO_2022.pptx

17:00 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 S3. In these theories, the S3 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 can accommodate hierarchical quark and charged lepton masses, and examine the resulting phenomenological implications in each case. We find a heavier spectrum for the superpartner masses compared to flavored gauge mediation models controlled by Abelian symmetries, which can be directly traced back to the need in our scenarios for two vectorlike pairs of messenger fields for viable electroweak symmetry breaking.

Speaker: SHU TIAN EU

pikimo2022_ShuTian.pdf

pikimo2022_ShuTian.pdf

17:15 Cosmological Constraints on First-Order Phase Transitions

First-order phase transitions exist in many models beyond the Standard Model and can generate detectable stochastic gravitational waves for a strong one. Using the cosmological observables in big bang nucleosynthesis and cosmic microwave background, we derive constraints on the phase transition temperature and strength parameter in a model-independent way. For a strong phase transition, we find that the phase transition temperature should be above around 2 MeV for both reheating photon and neutrino cases. For a weak one with a temperature below 1 MeV, the phase transition strength parameter is constrained to be smaller than around 0.1. Implications for using a first-order phase transition to explain the NANOGrav observed gravitational wave signal is also discussed.

Speaker: MRUNAL PRASHANT KORWAR

Cosmological Constraints on First-Order Phase Transitions.pdf

Cosmological Constraints on First-Order Phase Transitions.pptx