# New methods and ideas at the frontiers of particle physics

US/Mountain
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Description

The following anti-covid protocols will be applied at the workshop:

1. requirement of a negative test before traveling;

2.  required vaccination boost for those eligible, otherwise full vaccination;

3. the Center has rapid antigen tests available.

Hotel Reservations
For block room price in Aspen Meadows Resort book early. The special rate for our block of rooms at the Meadows will not be guaranteed after February 17 or once our block has been filled. The rooms are large, so often people share who would not normally do so. There is a link to find a roommate on our registration page.

• Monday, March 21
• 8:00 AM 8:20 AM
Higgs Experimental 20m
Speaker: Kirill Prokofiev (The Hong Kong University of Science and Technology (HK))
• 8:25 AM 8:45 AM
Higgs theory 20m
Speaker: Marcela Silvia Carena Lopez (Fermi National Accelerator Lab. (US))
• 8:50 AM 9:10 AM
Top Experimental 20m
Speaker: Titas Roy (University of Illinois at Chicago (US))
• 9:45 AM 10:05 AM
Heavy neutron stars from light scalars 20m
Speaker: Reuven Balkin (Technion)
• 10:10 AM 10:30 AM
Electroweak Experimental 20m
Speaker: Ricardo Gonzalez Lopez (University of Liverpool (GB))
• 10:35 AM 10:55 AM
Electroweak/SMEFT 20m
Speaker: Gauthier Durieux (CERN)
• 4:30 PM 4:50 PM
QCD Experimental 20m
Speaker: Sandeep Kaur (Carleton University (CA))
• 4:55 PM 5:15 PM
A Cosmological Lithium Solution from Discrete Gauged Baryon Minus Lepton Number 20m

We propose the infrared gauge theory 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 (University of Chicago)
• 5:20 PM 5:40 PM
Machine Learning Theory 20m
Speaker: Phiala Shanahan (Massachusetts Institute of Technology)
• 6:15 PM 6:35 PM
Machine Learning Experimental 20m
Speaker: Philip Ilten (University of Cincinnati (US))
• 6:40 PM 7:00 PM
Exotica Experimental 20m
Speaker: Yurii Maravin (Kansas State University (US))
• 7:05 PM 7:25 PM
Maximizing Direct Detection with HYPER Dark Matter 20m

In this talk, I will estimate the maximum direct detection cross section for sub-GeV dark matter scattering off nucleons. For dark matter masses in the range of 10 keV − 100 MeV, cross sections greater than 10^(-36) - 10^(-30) cm^2 seem implausible. I will also 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
• Tuesday, March 22
• 8:00 AM 8:20 AM
Belle II: Recent Results, Status, and Prospects 20m

The Belle II experiment started data collection at the SuperKEKB facility in 2019, after a period of detector commissioning. More than 200 fb-1 have been logged thus far. This presentation will include physics results and prospects, as well as the status of and plans for the experiment.The Belle II experiment started data collection at the SuperKEKB facility in 2019, after a period of detector commissioning. More than 200 fb-1 have been logged thus far. This presentation will include physics results and prospects, as well as the status of and plans for the experiment.

Speaker: Kay Kinoshita (University of Cincinnati)
• 8:25 AM 8:45 AM
The LHCb experiment's quest for new physics beyond the Standard Model 20m
Speaker: Marina Artuso (Syracuse University (US))
• 8:50 AM 9:00 AM
HH Searches with ATLAS 10m

Exploring the Higgs potential and electroweak symmetry breaking is one of the main goals of the LHC. Higgs pair production (HH) provides experimental access to the shape of Higgs potential as it is the only direct probe of the Higgs self-coupling in proton-proton collisions. In 2021, ATLAS combined new results using the full Run 2 dataset (139/fb) from both 𝑏𝑏 ̄𝜏+𝜏− and 𝑏𝑏 ̄𝛾𝛾 channels to produce the most stringent limits on Standard Model (SM) HH production and the Higgs self-coupling to date. These full Run 2 analyses and their combination have recently been extrapolated to 3000/fb at 14 TeV. This talk will discuss the latest Full Run 2 combined results and our projected sensitivity to HH production at the HL-LHC.

Speaker: Jannicke Pearkes (SLAC National Accelerator Laboratory (US))
• 9:10 AM 9:20 AM
Complementarity between Equivalence Principle violating tests and Precision searches 10m
Speaker: Abhishek Banerjee (Weizmann Institute of Science)
• 10:00 AM 10:20 AM
Experimental Kaon physics: Recent Results, Status, and Prospects 20m

Experimental Kaon physics has contributed to a remarkable number of discoveries, which have shaped fundamentally the Standard Model.
This presentation will review the recent results from the latest generation of kaon experiments, as well as the current status and prospects for the future.

Speaker: Karim Massri (CERN)
• 10:25 AM 10:45 AM
Global Constraints on CP-violating Yukawas 20m

With clear signals of physics beyond the Standard Model proven to be elusive both at high- and low-energy searches, it has become imperative to relate experimental data of various scales in an accurate and to a large extent model-independent manner in order to corner even the smallest new physics signals. In this talk, I focus on observables that probe CP violation from the quark and lepton sector without requiring sources of flavour violation beyond the SM. Within the EFT of SMEFT I present a global analysis of EDMs and constraints from the LHC, highlighting correlations between high-
energy and the high-intensity frontier as well as possible cancellations that cannot be captured without such a global approach.

Speaker: Emmanuel Stamou (TU Dortmund)
• 4:30 PM 4:50 PM
LLPs at LHC 20m
Speaker: Karri Folan Di Petrillo (Fermi National Accelerator Lab. (US))
• 4:55 PM 5:15 PM
New physics in rare B decays 20m
Speaker: Peter Stangl (University of Bern)
• 5:20 PM 5:40 PM
New searches for axions at Flavor Experiments 20m
Speaker: Diego Redigolo (CERN-INFN Florence)
• 6:15 PM 6:35 PM
NPOD (NP searches with optical dump) @ LUXE, theory 20m
• 6:40 PM 7:00 PM
NPOD (NP searches with optical dump) @ LUXE, experiment 20m
Speaker: Noam Tal Hod (Weizmann Institute of Science (IL))
• 7:05 PM 7:25 PM
Dark sector particles at fixed target experiments 20m
Speaker: stefania gori (UC Santa Cruz)
• Wednesday, March 23
• 8:00 AM 8:20 AM
Searching for Axion Dark Matter Below 1 $\mu$eV with ABRACADABRA and DMRadio 20m
Speaker: Jonathan Ouellet (Massachusetts Institute of Technology)
• 8:25 AM 8:45 AM
The latest axion dark matter search result with ADMX 20m

The axion is a leading candidate for dark matter arising from the Peccei-Quinn solution to the Strong CP problem. The Axion Dark Matter eXperiment (ADMX) searches for axion dark matter with a cylindrical cavity immersed in a strong magnetic field. The previous ADMX results achieved sensitivity to the DFSZ axions in the 2.7-3.3 micro eV with ultra-low noise RF readout realized by quantum amplifiers and a dilution refrigerator. In this presentation, we will report the latest results from a search for the axion dark matter in the 3.3-4.2 micro eV mass range.

Speaker: Tatsumi Nitta
• 8:50 AM 9:10 AM
New Observational Constraints on Dark Sectors¶ 20m
Speaker: Tomer Volansky (Tel Aviv University (IL))
• 9:45 AM 10:05 AM
New horizons: Searches for scalar and vector ultralight dark matter 20m

The last decade has seen unprecedented effort in dark matter model building at all mass scales coupled with design of numerous new detection strategies. Transformative advances in quantum technologies have led to a plethora of new high-precision quantum sensors and dark matter detection strategies of ultralight (< 10 eV) dark matter. I will give a broad overview of searches for scalar and vector ultralight dark matter following the Snowmass community paper and focus on searches with atomic and nuclear clocks, optical cavities, and atom interferometers.

Speaker: Marianna Safronova
• 10:10 AM 10:30 AM
Optomechanical searches for dark matter 20m
Speaker: David Moore (Yale University)
• 10:35 AM 10:55 AM
Quantum noise limits and how to get around them in the search for new physics 20m

A rapidly increasing number of experimental programs in HEP are reaching the point where their sensitivity is limited by quantum mechanical noise in the readout systems. Key examples include various axion searches and searches for dark matter with mechanical sensors. I will give an overview of the theory of quantum limited measurements in these systems. In particular I'll give a pedagogical explanation of the so-called "Standard Quantum Limit", and discuss some methods to get to noise levels below this limit.

Speaker: Daniel Carney (Berkeley National Lab)
• 4:30 PM 6:30 PM
Public Talk 2h
Speaker: Lina Necib (California Institute of Technology)
• 6:40 PM 7:00 PM
Probing dark sector physics using Galactic Substructure 20m
Speaker: Oren Slone
• 7:05 PM 7:25 PM
Natural factories for dark portals and their signatures in neutrino observatories 20m

Nature provides us with a host of energetic astrophysical beams'' such as cosmic rays, solar and atmospheric neutrinos. When colliding with ordinary matter all of these astrophysical fluxes can act as a factory for light new physics. They will supply irreducible fluxes of BSM particles which can be searched for inside neutrino experiments (and dark matter detectors). In this talk I will outline how XENON-1T, Super Kamiokande, and future experiments like DUNE and JUNO can probe portals to a dark sector using existing and future data.

Speaker: Ryan Plestid
• Thursday, March 24
• 8:00 AM 8:20 AM
Scanning the X-ray Sky for Dark Matter 20m
Speaker: Kerstin Perez
• 8:25 AM 8:45 AM
Gravitational waves at frequencies above 10 kHz 20m

Gravitational waves (GWs) at frequencies higher than the LIGO band can bring us completely new information about the universe. Besides being the most-interesting frequency region for looking at cosmological phenomena, they can also convey signatures of ultralight bosons through blackhole superradiance and light primordial blackholes (PBHs). I will introduce a new global initiative to study GW sources and detectors at ultra-high-frequencies (MHz-GHz), as well as a new experiment at Northwestern University to look for GWs in the frequency band of 10 kHz to 300 kHz using levitated optomechanical sensors. I will summarize the design, the current experimental progress, as well as a path forward for future improvements.

Speaker: Nancy Aggrawal
• 8:50 AM 9:10 AM
Dark Matter in the Milky Way 20m
Speaker: Lina Necib (California Institute of Technology)
• 9:45 AM 10:05 AM
Compact Objects as a Universal Probe of  Bosonic Dark Matter 20m
Speaker: Devin Walker
• 10:10 AM 10:30 AM
Primordial gravitational waves boosted by the axion 20m

I will discuss how early dynamics of the axion can naturally induce a matter-kination era inside the standard radiation era. The matter-kination era imprints a smoking-gun gravitational-wave peak on the irreducible inflationary gravitational-wave background, whose position depends on kination's energy scale and duration. Remarkably, the gravitational-wave peak lies inside LISA, as well as ET, and CE sensitivity windows. Future gravitational-wave observatories will thus offer a new window on axion models.

Speaker: Geraldine Servant (Deutsches Elektronen-Synchrotron (DE))
• 10:35 AM 10:55 AM
An axion dark matter-induced echo of supernova remnants 20m

In the presence of radiation from bright astrophysical sources at radio frequencies, axion dark matter can undergo stimulated decay to two nearly back-to-back photons, meaning that bright sources could have a counterimage (''gegenschein'') in nearly the exact opposite spatial direction if axions comprise the dark matter. The counterimage will be spectrally distinct from backgrounds, taking the form of a narrow radio line centered at half the axion mass with a width determined by Doppler broadening in the halo. I will discuss how the axion decay-induced echoes of supernova remnants may be bright enough to be detectable with ongoing observations from the FAST radio telescope.

Speaker: Katelin Schutz (McGill University)
• 4:30 PM 4:50 PM
Asteroids as a microhertz gravitational-wave detector 20m

The science case for a broad program of gravitational wave (GW) detection across all frequency bands is exceptionally strong. At present, there is a dearth of coverage by existing and proposed searches in the GW frequency band lying between the peak sensitivities of PTAs and LISA, roughly 0.1-100 microhertz. In this talk, I will outline a conceptual mission proposal to access this band. I will demonstrate that a few carefully chosen asteroids which orbit in the inner Solar System can act as excellent naturally occurring gravitational test masses despite the environmental noise sources. As such, a GW detector can be constructed by ranging between these asteroids using optical or radio links. At low frequencies, I will discuss how gravity gradient noise arising from the combined motion of the other ~10^6 asteroids in the inner Solar System sharply cuts off the sensitivity of this proposal. Sensitivity in the middle of this band is mostly limited by various solar perturbations to the asteroid test masses, while the high-frequency sensitivity is limited by noise in the ranging link. The projected strain-sensitivity curve that I will present indicates significant potential reach in this frequency band for a mission of this type.

Speaker: Michael Fedderke (Johns Hopkins University)
• 4:55 PM 5:15 PM
Dark Matter from Axion Strings 20m

Axions are hypothetical particles that may explain the observed dark matter (DM) density and the non-observation of a neutron electric dipole moment. An increasing number of axion laboratory searches are underway worldwide, but these efforts are made difficult by the fact that the axion mass is largely unconstrained. If the axion is generated after inflation there is a unique mass that gives rise to the observed DM abundance; due to nonlinearities and topological defects known as axion strings, computing this mass accurately has been a challenge for four decades. Recent works, making use of large static lattice simulations, have led to largely disparate predictions for the axion mass, spanning the range from 25 microelectronvolts to over 500 microelectronvolts. In this talk, I will show that adaptive mesh refinement (AMR) simulations are better suited for axion cosmology than the previously-used static lattice simulations. Using dedicated AMR simulations we obtain an over three orders of magnitude leap in dynamic range and provide evidence that axion strings radiate their energy with a scale-invariant spectrum, to within ∼5% precision, leading to a mass prediction in the range (40,180) microelectronvolts.

Speaker: Malte Buschmann
• 5:20 PM 5:40 PM
Searching for Dark Particles with Light (and Quantum Technologies) 20m

New particles that interact feebly with ordinary matter could appear “dark” to us. Quantum sensors, given their low noise level, are promising devices to look for such new particles that feebly interact with photons. A well-known example is the axion (or axion-like-particle), which arises in many extensions of the Standard Model. We propose to use two superconducting radio-frequency cavities with resonant frequencies in the GHz range to look for axions. The search strategy is a broadband search using a light-shining-through-wall setup. Superconducting radio-frequency cavities have an exceptionally high quality factor, which both boost the number of photons stored in the emitter cavity, and enhance the signal power in the receiver cavity, and hence are ideal to search for light axion with mass below 10 micro eV. In the future, other quantum devices, such as thin-film lithium niobate microring resonators can search for axions at optical frequency.

Speaker: Christina Gao
• 6:15 PM 6:35 PM
Muon g-2 theory: status and prospects 20m
• 6:40 PM 7:00 PM
(g-2)_\mu - theory predictions by BMW 20m
Speaker: Zoltan Fodor (Wigner Research Centre for Physics (Wigner RCP) (HU))
• 7:05 PM 7:25 PM
(g-2)_\mu - experiment 20m
Speaker: Rebecca Chislett
• Friday, March 25
• 8:00 AM 8:20 AM
Hidden Naturalness in the Light of Precision Cosmological Data 20m
Speaker: Saurabh Bansal (University of Cincinnati)
• 8:25 AM 8:45 AM
Cosmological probes of dark matter interactions 20m
Speaker: Kimberly Boddy (University of Texas at Austin)
• 8:50 AM 9:10 AM
Precision Calculation of Inflation Correlators at One Loop 20m

We initiate a systematic study of precision calculation of the inflation correlators at the 1-loop level, starting in this paper with bosonic 1-loop bispectrum with chemical-potential enhancement. Such 1-loop processes could lead to important cosmological collider observables but are notoriously difficult to compute due to the lack of symmetries. We attack the problem from a direct numerical approach based on the real-time Schwinger-Keldysh formalism and show full numerical results for arbitrary kinematics containing both the oscillatory "signals" and the "backgrounds". Our results show that, while the non-oscillatory part can be one to two orders of magnitude larger, the oscillatory signal can be separated out by applying appropriate high-pass filters. We have also compared the result with analytic estimates typically adopted in the literature. While the amplitude is comparable, there is a non-negligible deviation in the frequency of the oscillatory part away from the extreme squeezed limit.
See arXiv:2109.14635 for more details.

Speaker: Yiming Zhong (University of Chicago)
• 9:45 AM 10:05 AM
Searching for Light (but Massive) Relics in Cosmology 20m

New light degrees of freedom are ubiquitous in extensions of the Standard Model. Even if feebly interacting, these new particles can be cosmologically populated as light relics, which allows for powerful searches using cosmology. In this talk I will describe how to leverage cosmological data sets to search for new light–but not necessarily massless–degrees of freedom. Massless relics act as a simple change in the number (N_eff) of effective neutrinos. Light but Massive Relics (LiMRs), however, can also affect the clustering of matter, similarly to massive neutrinos. I will show how to search for these relics, and present constraints using current CMB+LSS data, which can test a large part of the relic parameter space. As an example, we set the tightest upper limit on the gravitino mass at 2.5 eV.

Speaker: Julian Munoz (Harvard-Smithsonian Center for Astrophysics)
• 10:10 AM 10:30 AM
What microhalos can tell us about the origins of dark matter 20m

As remnants of the earliest stages of structure formation, the smallest dark matter halos provide a unique probe of the evolution of the Universe prior to the onset of Big Bang nucleosynthesis (BBN). I will discuss how the pre-BBN expansion history can enhance the microhalo population, thereby boosting the dark matter annihilation rate if dark matter is a thermal relic. The amplitude of this boost is highly sensitive to the size of the smallest halos, which provides an additional window into the dynamics and particle content of the early Universe. The nonthermal production of dark matter can even suppress halo formation on kiloparsec scales. It is therefore possible to use astronomical observations to learn about the origins of dark matter and the evolution of the Universe during its first second.

Speaker: Adrienne Erickcek (University of North Carolina at Chapel Hill)
• 10:35 AM 10:55 AM
Dark Photons and the Cosmic Radiation Background 20m

The dark photon is a well-motivated extension of the Standard Model which can mix with the regular photon. This mixing is enhanced whenever the dark photon mass matches the primordial plasma frequency, leading to resonant conversions between photons and dark photons. These conversions can produce observable cosmological signatures, including distortions to the cosmic radiation background. In this talk, I will discuss a new analytic formalism for these conversions that can account for the inhomogeneous distribution of matter in our universe, leading to new and revised limits on the mixing parameter of light dark photons derived from the COBE/FIRAS measurement of the cosmic microwave background spectrum.

Speaker: Hongwan Liu
• 4:30 PM 4:50 PM
Superfluid Effective Field Theory for Dark Matter Direct Detection 20m

I will present an effective field theory (EFT) framework for superfluid He4 to model the interactions among quasiparticles, helium atoms, and probe particles. The proposed EFT framework and results can be used to understand the dynamics of thermalization in the superfluid. They can be further applied to sub-GeV dark matter direct detection with superfluid 4He.

Speaker: Wei Xue (University of Florida (US))
• 4:55 PM 5:15 PM
Standard Model Physics for BSM Searches in Neutrino Experiments 20m
Speaker: Shirley Li (Fermilab)
• 5:20 PM 5:40 PM
Rydberg atom photon detectors for axion searches 20m

Astrophysical observations give overwhelming evidence for the existence of dark matter. Several theoretical particles have been proposed as dark matter candidates, including axions and weakly interacting massive particles (WIMPs). Dark matter axions may be detected through their conversion into photons in the presence of a magnetic field. At Yale, we are searching for axions in the 10 − 50 μeV mass range with the HAYSTAC experiment and developing new a technique for detecting photons based on Rydberg atoms that will enable searches up to 500 μeV, following the proof-of-principle developed for the CARRACK experiment. Rydberg atoms are efficient single-photon counters in the microwave regime to their large electric dipole moment between adjacent levels. The transitions can reach frequencies above which qubits can reliably operate. I will discuss status of HAYSTAC and the development of the Rydberg atom effort.

Speaker: Reina Maruyama
• 5:45 PM 6:05 PM
Challenging the Standard Model with IceCube 20m

The IceCube Neutrino Observatory located near the geographical South Pole has measured the spectra of high-energy atmospheric and astrophysical neutrinos. Using the data collected over more than ten years, IceCube has performed searches for new neutrino forces, partners, and space-time symmetries have been performed. This talk will review recent results on beyond Standard Model measurements with IceCube.

Speaker: Carlos Arguelles (MIT)