Mitchell Conference on Collider, Dark Matter, and Neutrino Physics 2026

May 27, 2026, 8:00 AM → May 30, 2026, 10:40 PM America/Chicago

Hawking Auditorium (Texas A&M University Mitchell Institute)

In association with the Physics Department at Sam Houston State University, the 2026 Mitchell Conference on Collider, Dark Matter, and Neutrino Physics will be held on May 27-30, 2026 at the George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University. The conference will focus on recent developments in the fields of colliders, dark matter, and neutrino physics. The conference will be attended by experimental and theoretical experts from these fields, and plenty of time will be allocated for interaction, discussion, and collaboration.

Venue
Texas A&M University, College Station, Texas
Mitchell Institute (MIST), Hawking Auditorium

Internet Access
Guest internet instructions will be provided with your welcome packet. Some guests have had connectivity issues in the past, so we highly recommend that you set up Eduroam if your home institution supports it. The setup requires an internet connection, so it needs to be done beforehand. Once done it will allow you hassle-free internet access at more than 400 academic institutions around the US. Please contact your IT support for assistance.

Conference Website
More details on transportation, lodging, and parking are available at the conference website. 

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Organizers
Amanda Kabella (Admin)

Aashwin Basnet

Stephane Cooperstein

James Dent

Bhaskar Dutta

Isabelle Goldstein

Teruki Kamon

Kevin Kelly

Mudit Rai

Deepak Sathyan

Austin Schneider

William Shepherd

Louis Strigari

Joel Walker

Wed, May 27

1 Welcome

Speaker: Kevin Kelly (Texas A&M University)

Mitchell_Intro_2026.pdf

Wednesday Morning: Wednesday Morning 1

Convener: Dr Deepak Sathyan

2 Neutrino-Dark Matter Interactions: From EFT to UV Completions

Abstract pending

Speaker: Ks Babu (Oklahoma State University)

Mitchell_2026_Babu.pdf

3 Quantum Information Science and the S-matrix

To what extent can quantum information science (QIS) tell us new things about the S-matrix? For example, can you derive the symmetries of the S-matrix from QIS principles? Conversely, can known properties of the S-matrix: the language of gauge invariance, flavor symmetries, Ward identities, etc. - be reframed in equivalent QIS terms? I will review some recent work done by our community on this frontier, with an emphasis on my own work on Yang Mills theories: https://arxiv.org/abs/2511.09623 . Specifically, I will look at the S-matrix in Yang Mills as an SU(N)-equivariant kernel, and analyze the entanglement it generates.

Speaker: Kuver Sinha (University of Oklahoma)

Sinha_Mitchell_2026.pdf

4 Quantum Observables and Higher-Order effects in $h \to VV^*$ Decays

Angular correlations in Higgs decays to electroweak gauge bosons, $h\to ZZ^*, WW^*$, provide a powerful probe of both new physics effects and quantum information observables. We present a systematic study of these Higgs decays, including NLO QCD and NLO electroweak corrections. We find that QCD effects induce modest percent-level shifts in the angular observables, while electroweak corrections can significantly reshape the angular structure, particularly in the $h\to ZZ^*$ channel. We then assess how these effects impact the validity of the effective two-qutrit description and the associated entanglement measures.

Speaker: dorival Gonçalves (Oklahoma State University)

Dorival_Texas_2026.pdf

5 Electromagnetic properties of neutrions: magnetic moments and neturino polarizibility

In this talk, I first present a mechanism for generating neutrino magnetic moments without generating corresponding neutrino mass. With a careful choice of $SU(2)_L$ representations for the fields running in the loop, only the dipole operator involving the neutral $SU(2)_L$ gauge boson is generated. The corresponding mass diagram, obtained by removing the external gauge boson, simply vanishes. I will show explicit UV completions that realize this idea and give magnetic moments within reach of current and upcoming experiments.

In the second part I turn to neutrino polarizability, a dimension-7 operator that couples two neutrinos to two photons. I also consider the case where one of the active neutrinos is replaced by a sterile state, and derive new constraints on the active-sterile polarizability using single-photon neutrino-nucleus scattering. Interestingly, a light-mediator realization of this operator can accommodate the MiniBooNE low-energy excess while remaining consistent with existing limits.

Speaker: Anil Thapa (Colorado State University)

nmm_Mitchell_anil_2026.pdf

Coffee Break

Wednesday Morning: Wednesday Morning 2

Convener: Shirley Li (UC Irvine)

6 Quantum uncertainty and the expansion of the universe

I will discuss a new approach to understanding the accelerated expansion of the universe that connects quantum mechanics and general relativity at the level of horizon kinematics. This idea gives rise to a geometric modification of the Friedmann equation with no new particles or fields and makes testable predictions with current and next-generation surveys.

Speaker: Savvas Koushiappas

7 Primordial Black Hole Dark Matter from Accretion During Early Matter Domination

We present a scenario where primordial black holes (PBHs) formed in a radiation-dominated (RD) phase undergo significant accretion during a period of early matter dominated (EMD), as a result of which their mass can grow by up to two orders of magnitude. Restricting to the linear perturbation regime, we compute the gravitational wave (GW) spectrum that features two peaks: a high-frequency peak associated with the PBH formation in the RD phase, and a low-frequency peak due to the sudden transition from EMD to the standard RD phase. We show that one or both peaks can be observed by a combination of different GW detectors for PBHs in the asteroid mass window, where they could comprise the totality of dark matter.

Speaker: Rouzbeh Allahverdi (University of New Mexico)

Allahverdi_Mitchell26.pdf

8 Neutrino BSM: The good, the bad, and the unlikely

Abstract pending

Speaker: Ian Shoemaker (Virginia Tech)

Mitchell 2026.pdf

9 The String Axiverse Under Pressure: Calabi-Yau Geometry Meets Experimental Data

String compactifications generically predict many axion-like fields, but their properties are not arbitrary: in type IIB Calabi-Yau compactifications, axion masses, decay constants, and relic abundances are controlled by divisor volumes, intersection numbers, and the Kähler metric. I will work with explicit Calabi-Yau hypersurfaces from the Kreuzer-Skarke database, using CYTools to extract the geometric inputs needed for the four-dimensional axion theory.

I will first describe results on fuzzy axions and associated relics in explicit compactifications. I will then turn to a more systematic framework for Bayesian inference on Calabi-Yau moduli spaces, where a key step is the ability to robustly sample the Kähler cone of a given geometry using MCMC walkers. Repeating this geometry by geometry allows us to explore how string-derived axion priors vary across explicit compactifications and how cosmological data constrains them. I will close with ongoing work on the instanton consistency conditions needed to generate axion potentials, including Freed-Witten quantization, rigidity, and intersection-curve constraints.

Speaker: Dr Mudit Jain

MJ_talkMay2026@MitchellTAMU_2.pdf

Lunch

Wednesday Afternoon: Wednesday Afternoon 1

Convener: Aashwin Basnet (Texas A & M University (US))

10 Electroweak Restoration: SMEFT and HEFT

Colliders continue to push our understanding of electroweak (EW) interactions to ever higher energies. At high energies, the broken EW theory measured is expected to converge to the unbroken theory. This is the electroweak restoration regime. In this talk we investigate how linear and non-linear realizations of the EW symmetry can be probed by comparing the relative longitudinal di-boson production rates: $f\bar{f}'\rightarrow V_LV'_L$ and $f\bar{f}'\rightarrow V_Lh$, where $V_L,V'_L$ are longitudinal gauge bosons, $h$ is the Higgs boson, and $f,f'$ are SM fermions. For the linear beyond the SM theory we use the Standard Model Effective Theory (SMEFT) and for the non-linear BSM theory we us Higgs Effective Field Theory (HEFT). We give a general discussion of these amplitudes and partonic cross sections in the SM, SMEFT, and HEFT. In particular, we investigate how the ratios of these different rates are sensitive to linear vs. non-linear EW symmetry. We find that the ratios of $W^\pm_LZ_L$ and $W^\pm_L h$ rates are particularly theoretically clean since these are expected to converge to one for the SM and SMEFT but not necessarily HEFT. Additionally, $W^\pm Z$ provides a particularly experimentally clean channel to measure the gauge boson polarizations.

Speaker: Ian Lewis (The University of Kansas)

IML_Mitchell.pdf

11 Searching for axinos and displaced vertices with the ATLAS detector

Collider searches for long-lived particles (LLPs) that travel an observable distance inside a detector before decaying have become increasingly common in the past decade. Many theories of Beyond the Standard Model physics predict such particles with a variety of potential lifetimes, and searches for these particles have required the introduction of new, innovative experimental techniques. In this talk, I will present recent results from a search performed by the ATLAS experiment with data taken during run 2 of the Large Hadron Collider looking for one particularly distinctive signature: a reconstructable displaced vertex from the decay of a LLP in the charged particle tracker, plus missing transverse momentum from an invisible particle escaping the detector. I will discuss some of the potential interpretations of this result, including limits set on a new supersymmetric model containing the QCD axion, and I will show how a search like this one can be used to constrain the parameter space for the axion itself.

Speaker: Benjamin John Rosser (University of Chicago (US))

bjr_mitchell_dvmet_axinos.pdf

12 Di-Higgs searches at the LHC

Higgs boson pair production (HH) plays a central role in probing the Higgs boson self-interactions, which are key to understanding the shape of the Higgs potential and the mechanism of electroweak symmetry breaking. This talk presents the latest results from the ATLAS and CMS experiments on non-resonant Higgs boson pair production, based on the full Run 2 dataset collected at $\sqrt{s}$ = 13 TeV, with the inclusion of available Run 3 results where available. These analyses provide sensitivity to the Higgs boson self-coupling and the quartic VVHH coupling, offering key tests of the Higgs sector beyond single-Higgs measurements. The talk further includes projections for future sensitivity at the High-Luminosity LHC, outlining the expected improvements and challenges ahead.

Speaker: Rachel Jordan Hyneman (University of Arizona (US))

Mitchell2026_HHSearches_Hyneman.pdf

13 Expanding Discovery Potential through Novel Trigger Strategies at the Energy Frontier

The absence of significant excesses at the LHC underscores the imperative to expand sensitivity to uncovered and unexplored regions of phase space, which is often trigger-limited. This talk will focus on the development of novel trigger techniques for long-lived particles and anomaly detection deployed at the CMS experiment in LHC Run 3, and how these approaches enable significant physics gains. I will also examine how these strategies must evolve to meet the challenges of the High-Luminosity LHC and future collider environments.

Speaker: Kiley Elizabeth Kennedy (Princeton University (US))

Mitchell_KKennedy_05.27.2026.pdf

Coffee Break

Wednesday Afternoon: Wednesday Afternoon 2

Convener: dorival Gonçalves (Oklahoma State University)

14 Electromagnetic Dirac Cogenesis

We propose a novel cogenesis mechanism by utilising the two-body decay of heavy vector-like fermions to dark matter (DM) $\chi$ and right chiral part of light Dirac neutrino $\nu_R$ via the electromagnetic dipole operator. This leads to generation of asymmetry in dark fermion $\chi$ as well as $\nu_R$ with the latter getting transferred to left-handed lepton doublets via Yukawa interactions with a neutrinophilic Higgs doublet. While lepton asymmetry is converted into baryon asymmetry of the Universe via electroweak sphalerons, the dark fermion asymmetry results in asymmetric dark matter. Since CP asymmetries in lepton and dark sector are equal and opposite due to net lepton number conservation, DM mass is restricted to a fixed value $\sim O$(1) GeV. Long-lived nature of DM keeps indirect detection prospects at gamma-ray telescopes alive while thermalised light Dirac neutrinos lead to observable dark radiation at cosmic microwave background (CMB) experiments. Heavy vector-like fermions can be probed at terrestrial experiments via their electromagnetic dipole interactions.

Speaker: Dr Arnab Dasgupta (PITT-PACC)

arnab_asymmetry Texas A&M.pdf

15 Reviving WIMP dark matter with temperature-dependent couplings

The persistent null results at dark matter (DM) direct-detection experiments have pushed the popular weakly interacting massive particle (WIMP) DM to tight corners. Generic WIMP models with direct-detection rate below the current upper limits often lead to a thermally overproduced relic abundance after freeze-out. To resolve this conundrum, we propose a novel scenario where DM has temperature-dependent couplings with the standard model (SM) bath. A scalar field having a large vacuum expectation value (VEV) at high temperatures generates sizeable DM-SM interactions leading to efficient DM annihilations responsible for generating the desired thermal relic. At lower temperatures, the scalar field VEV settles down to a small value as a result of a phase transition which can generically be of first order, effectively leading to suppressed DM-SM interaction rate at low temperature, consistent with null results at direct-detection experiments. Upper bound on thermal DM mass forces the first-order phase transition (FOPT) to occur at scales such that the corresponding gravitational wave signal remains within reach of future experiments like LISA.

Speaker: Dr Debasish Borah (Indian Institute of Technology Guwahati)

Mitchell26_dborah.pdf

16 Physics Reach and the Status of DUNE

The neutrino flavor oscillation, discovered and confirmed through mid-2000s is a firmly established phenomenon. Since the flavor oscillation occurs due to the fact that the flavor and mass eigenstates differ, it requires the Standard Model to be modified. Precision measurements of the neutrino properties to reflect their non-zero mass into the Standard Model require high statistics samples of neutrino interactions. To provide the essential information for the modifications of the Standard Model, two next-generation long baseline neutrino experiments are under construction on either side of the Pacific. The Deep Underground Neutrino Experiment (DUNE) in the U.S. and the Hyper-Kamiokande (HK) experiment in Japan utilize high-power proton beams of energy 120GeV and 30GeV, respectively, together with the large mass far detectors and powerful near detectors. This talk will cover DUNE’s latest expected physics reach for neutrino oscillation properties, including the potential for the discovery of CP violation in the neutrino sector, the potential for supernova neutrino measurements, and the expanded physics reach going beyond the oscillation measurements, which becomes possible thanks to the powerful facilities these next-generation neutrino experiments utilize. This talk will also cover the status of the experiment and its latest timeline.

Speaker: Prof. Jae Yu (University of Texas at Arlington (US))

yu-dune-mitchell2026-short.pdf

yu-dune-mitchell2026-short.pptx

Wednesday Evening Reception: Reception

Thu, May 28

Thursday Morning: Thursday Morning 1

Convener: Isabelle Goldstein (Texas A&M University)

17 A likelihood analysis for gamma-ray background models

Indirect searches for dark matter using dwarf spheroidal galaxies are limited by systematic uncertainties in modeling diffuse gamma-ray backgrounds. We present a likelihood-based comparison of locally constructed empirical background models and theoretically-motivated models which incorporate the Fermi-LAT diffuse background. The empirical models include both an independent-binning approach and a covariance-based model that captures cross-energy correlations. Using ensembles of blank-sky regions and information criteria to account for model complexity, we find that empirical background descriptions provide a statistically competitive fit to gamma-ray data on degree scales in high-latitude regions.

Speaker: Jason Kumar

Mitchell2026a.pdf

18 The Precision Frontier of Dark Matter Constraints from Direct Acceleration Measurements

For over a century, our understanding of dark matter has hinged on kinematic estimates of accelerations derived from static snapshots of stellar positions and velocities. However, kinematic methods can be inaccurate for a time-dependent potential, and there are now many lines of observational evidence that show that our Galaxy has had a highly dynamic history. Over the last several years, we have developed techniques to carry out extreme-precision time-series measurements of the accelerations of stars that live within the gravitational potential of our Galaxy.

I will discuss our comprehensive observational strategy to directly measure Galactic accelerations. Central to this discussion is our recent analysis of compiled pulsar timing data from which we were able to measure the Galactic acceleration for the first time, and derive fundamental Galactic parameters. Discernible differences in sub-structure exist among popular dark matter models on small scales, presenting testable nuances. We have recently obtained the first constraints on a dark matter sub-halo near the Sun from pulsar timing. In the near future, we expect that our ongoing observational campaigns using pulsar timing, eclipse timing, and extreme-precision radial velocity observations should help to determine the dark matter sub-halo mass function in the Milky Way.

Speaker: Sukanya Chakrabarti

19 Mapping out the Dark Matter in the Milky Way with Stars

In this talk, I will explore the interfacing of simulations, observations, and machine learning techniques to construct a detailed map of Dark Matter in the Milky Way, focusing on the Galactic Center/Halo and dwarf galaxies. For the Galactic Halo, I will present a recent work leveraging Gaia DR3 that reveals a decline in the stellar circular velocity, inducing tensions with established estimates of the Milky Way's mass and Dark Matter content. I will discuss how the underestimated systematic errors in such a common methodology necessitates a revised approach that combines theory, observations, and machine learning. In dwarf galaxies, I will present a novel Graph Neural Network methodology that facilitates the accurate extraction of Dark Matter density profiles, validated against realistic simulations, and applied to two dwarf galaxies. I will conclude with a discussion on the future trajectory of astroparticle physics, emphasizing the need for the integration of astrophysical probes, particularly those of stellar dynamics, with our understanding of Dark Matter in the Galaxy and its connection with Dark Matter detection experiments.

Speaker: Lina Necib (MIT)

Necib.pdf

Necib.pptx

20 The Large Magellanic Cloud and dark matter direct detection across mass scales

The Large Magellanic Cloud (LMC) can significantly impact the dark matter halo of the Milky Way, and modify the dark matter velocity distribution in the Solar neighborhood. Cosmological simulations that sample potential Milky Way formation histories provide a powerful framework to characterize the dynamical imprint of the LMC-Milky Way interaction on the local dark matter distribution. I will discuss the impact of the LMC on the local dark matter distribution in state-of-the-art cosmological simulations. I will then present the implications for dark matter direct detection, considering both standard and non-standard dark matter interactions, and covering light and heavy dark matter searches.

Speaker: Nassim Bozorgnia

Bozorgnia-Mitchell2026.pdf

Coffee Break

Thursday Morning: Thursday Morning 2

Convener: Aparajitha Karthikeyan (Department of Physics and Astronomy, Texas A&M University)

21 The Dark Side of the Muon

High-energy muon colliders represent a compelling option for a future collider program, offering unique and rich physics opportunities. At sufficiently high energies, the muon can be thought of as having constituents described by muon parton distribution functions (PDFs). In this seminar, I present an analysis strategy for probing Beyond the Standard Model (BSM) physics through modifications to the muon PDFs induced by BSM physics, leading to observable signatures at a future muon collider. As a concrete case study, I apply this framework to an $L_\mu-L_\tau$ gauge boson and demonstrate that, for masses in the range of approximately 50–100 GeV, this indirect PDF-based approach outperforms traditional searches relying on direct gauge-boson production. These results highlight muon-PDF probes as a powerful and promising avenue for BSM physics searches at a future muon collider.

Speaker: Tien-Tien Yu (University of Oregon (US))

MuonPDFs.pdf

22 Neutrino Physics at a Muon Collider

In this talk I will present some unique opportunities that a high-energy muon collider offers in answering key neutrino-related questions. There is a community effort trying to identify questions that cannot be addressed by current or near-future experiments, with an emphasis on exploring new physics through neutrino interactions at such a collider. I will summarize some benchmark physics cases within the SM and beyond that have been studied in the recent years. Furthermore, I will summarize the current designs for various detector options and demonstrate the neutrino fluxes at different stages of the experiment. I will demonstrate the results of some SM as well as BSM cases studied so far, including non-standard neutrino interactions, neutrino cross section measurements, etc..

Speaker: Zahra Khajeh Tabrizi

MitchelConference_May2026.pdf

23 Neutrinos in Muon Collisions

Future muon colliders offer direct access to neutrino interactions at TeV scales. At high energies, electroweak radiation qualitatively reshapes lepton collisions: energetic muons can radiate W bosons, generating an intense flux of neutrinos within the beam and effectively turning the collider into a source of neutrino–lepton collisions. In this talk, I introduce an electroweak parton framework to describe this regime and show that these neutrino-initiated processes provide qualitatively new probes of leptonic interactions. I demonstrate that these measurements complement both traditional collider observables and low-energy neutrino scattering, enabling order-of-magnitude gains in sensitivity to effective operators, including previously unexplored flavor structures. This establishes muon colliders as a powerful new laboratory for neutrino-coupled new physics at high energies.

Speaker: Dr Innes Bigaran (Fermilab and Northwestern University)

Mitchell_Bigaran.pdf

24 New interpretations of the cosmological preference for a negative neutrino mass

Recent observations of the cosmic microwave background and baryon acoustic oscillations show some tension with the expectations of LCDM cosmology, favoring a non-standard expansion history and placing uncomfortably strong constraints on neutrino mass. Both effects can be interpreted as a negative neutrino mass parameter, one describing the change to the expansion history and the other one describing enhanced lensing. I will show how these tensions can be solved with a single change either to the lensing of the CMB or the expansion of the universe. I will discuss several examples of new physics which could account for the preference for negative neutrino mass, and which all illustrate the pattern that additional signals should appear if these tensions are explained by beyond the Standard Model physics.

Speaker: Joel Meyers (Southern Methodist University)

New Interpretations of the Cosmological Preference for Negative Neutrino Mass - Mitchell Conference.pdf

Lunch

Thursday Afternoon: Thursday Afternoon 1

Convener: Ian Lewis (The University of Kansas)

25 Exploring the Neutrino Sky With TAMBO

I will present the status of TAMBO.

Speaker: Prof. Carlos Arguelles Delgado (Harvard University)

TAMBO-Mitchell-2026.pdf

26 Leveraging EFTs to look for new physics in the electroweak sector at the LHC

Despite the spectacular success of the Standard Model (SM), the fundamental nature of physics beyond it (BSM) remains elusive. With the absence of direct discoveries at the LHC, I posit that precision measurements are a pathway to new physics. Standard Model Effective Field Theory (SMEFT) offers a robust framework to systematically parameterize and constrain the indirect, low-energy footprints of heavy new physics. In this talk, I will focus on the application of EFTs to probe the electroweak sector at the LHC. I will discuss how processes such as vector boson scattering (VBS), di- and triboson production, and Higgs-gauge boson interactions serve as highly sensitive probes for higher-dimensional operators. I will review recent experimental highlights from the ATLAS and CMS collaborations, addressing the theoretical and experimental challenges associated with global SMEFT measurements. Finally, I will outline the future prospects for electroweak EFT studies as the LHC progresses through Run 3 toward the High-Luminosity era, highlighting how these growing global constraints will help map the landscape of new physics.

Speaker: Saptaparna Bhattacharya (Southern Methodist University (US))

Mitchell_Final.pdf

27 Bump hunting with Energy Correlators

Energy correlators (ECs) provide a powerful tool to study QCD dynamics. On the one hand, they are infrared safe and precisely calculable in perturbation theory. On the other hand, they encode rich information about the underlying partonic dynamics. In this talk, I discuss their potential as probes of new physics, focusing on the case of a boosted light resonance hiding within SM jets. I show that the decay products of such a resonance imprint a characteristic bump in the EC spectrum, and present projected sensitivity demonstrating that this approach offers a theoretically clean and experimentally accessible handle on new physics searches at colliders.

Speaker: Lorenzo Ricci

EECMitchel.pdf

28 Shedding light on dark matter with mono-Higgs signature

Astrophysical evidence supports the existence of dark matter based on its gravitational interaction, and also suggests that dark matter interacts at most very weakly with the Standard Model particles. Many BSM theories predict the existence of dark matter particle candidates that can be produced and detected at high energy colliders, driving  experimental searches at the CERN LHC. After the discovery of the Higgs boson, we can probe the dark matter sector using this handle. In this talk, I will present a search for dark matter produced in association with the Higgs boson decaying to a pair of bottom quarks, using 13 TeV data collected by the CMS experiment at LHC.

Speaker: Shivani Lomte (University of Wisconsin Madison (US))

monoHiggsBB_CMS_MitchellConference_ShivaniLomte.pdf

Coffee Break

Thursday Afternoon: Thursday Afternoon 2

Convener: Joel Meyers (Southern Methodist University)

29 i-incidental N-naturalness

N-naturalness addresses the electroweak hierarchy problem by introducing N Standard Model copies with different Higgs mass-squared parameters. Reheating via a “reheaton” deposits most energy into one sector and smaller fractions into the others. While the Standard Model is usually identified with the sector having the lightest negative Higgs mass-squared, we show that resonant reheaton–Higgs mixing can preferentially reheat a heavier sector, allowing it to be identified as the Standard Model. This scenario satisfies current cosmological bounds, remains testable by future CMB and high-redshift surveys, and may produce a novel stochastic gravitational-wave signal from first-order QCD phase transitions across the other sectors.

Speaker: Brian Thomas Batell

Batell-Mitchell-2026.pdf

30 Fun with Gravitational Particle Production in Standard and Non-Standard Cosmologies

Since the pioneering work of Leonard Parker and collaborators in the 1960s, it has been known that the evolving cosmological spacetime can result in the production of particles in the frame of comoving observers. I will review how gravitational particle production works in a manner accessible to a broad audience. I will then describe a study of non-adiabatic particle production during the transition from inflation to reheating. In the limit of instantaneous reheating this calculation can be carried out analytically. I show that it is possible for the relic density of such particles to match the observed dark matter abundance for a scalar particle, minimally coupled to gravity, with a mass of ~ 10^-5 eV. I will then discuss the interesting ways in which this particle production may be altered in non-standard cosmological scenarios. Lastly, time permitting, I will discuss a variety of open and subtle questions regarding cosmological particle production in these scenarios, including the constraints on such models and, in particular, the generation of isocurvature perturbations.

Speaker: Prof. Andrew Zentner (University of Pittsburgh)

31 Gravity’s Gift: Baryons from the Big Bang

This talk is based on a recent paper in which my collaborators and I have explored how the cosmological excess of matter over antimatter can arise through the phenomenon of cosmological gravitational particle production at the end of inflation in a Type-I Seesaw model of nonthermal leptogenesis. From a model-building standpoint, this scenario is appealing for being minimal and economical, since some amount of gravitational production is unavoidable. From the phenomenological perspective, this scenario links the observed baryon asymmetry to the energy scale of inflation and the amplitude of inflationary gravitational waves. A non-detection of in measurements of CMB polarization would rule out this model.

Speaker: Andrew Long (Rice University)

Andrew_Long_Mitchell_2026--v1.pdf

Excursion

Fri, May 29

Friday Morning: Friday Morning 1

Convener: Andrew Long (Rice University)

32 Fractionally Charged Particles at the Energy Frontier

The pattern in the Standard Model (SM) charges can be traced to an ambiguity in the gauge group of the SM. The easiest way to resolve this ambiguity would be to discover a particle with electric charge that is an integer multiple of e/6 (beyond +/- e, 0). The discovery of such fractionally charged particles would also challenge and potentially rule out many minimal unification models. In this talk I will review the connection between the `global structure' of the SM and the charges (color singlet) particles can have, then explore the phenomenology of fractionally charged particles, focusing on the constraints provided by current searches at the Large Hadron Collider (LHC). By reinterpreting existing results, we assess the bounds on various fractionally charged representations, uncovering scenarios where collider limits are unexpectedly weak or entirely absent.

Speaker: Adam Martin (University of Notre Dame)

FCP_amartin_mitchell2026.pdf

33 Millicharged Particle Searches at the LHC with the MilliQan Experiment

Millicharged particles (mCPs) represent a striking example of exotic phenomenology stemming from a relatively simple hidden sector Dark Matter model. Moreover, fractionally charged particles remain subject to relatively few constraints from either indirect or direct observations at masses close to the electroweak scale. The milliQan experiment at the Large Hadron Collider is a subdetector of CMS whose aim is to search for mCPs at the energy frontier. This talk will present updated results from the milliQan bar detector’s Run 3 dataset at $\sqrt{s}$ = 13.6 TeV and $\mathcal{L}$ = 214.8$~\mathrm{fb}^{-1}$. In addition, the status of the slab detector’s ongoing data taking and projected future sensitivity to high mass mCPs will be discussed.

Speaker: Dariush Garvin Imani (Univ. of California Santa Barbara (US))

DariushImani_MitchellPresentation.pdf

34 Data-Driven Predictions for Dark Sector Particle Production

Accurate signal predictions are essential for interpreting and optimizing fixed-target searches for new physics. Even in minimal models such as the dark photon ($A'$) or millicharged particles (mCPs), theoretical uncertainties in hadronic production can be substantial. We introduce a data-driven framework that predicts both the rate and kinematic distributions of $A'$ and mCP production directly from measured dilepton events, without relying on specific theoretical production models. This method uses the close correspondence between amplitudes for emission of $A'$ or mCPs, and for off-shell Standard Model photon production, the latter being experimentally measurable in full differential form. We demonstrate that normalizing flow models can learn these distributions from data and serve as a fast, realistic Monte Carlo generator for dark sector signal simulations.

Speaker: Nikita Blinov (York University)

pres.pdf

35 Jeff Dror Talk

Abstract pending

Coffee Break

Friday Morning: Friday Morning 2

Convener: Jason Kumar

36 Improved supernova bounds on CP-even scalars from production and decay

Light scalars mixing with the Higgs boson are one of the few renormalizable dark sector portals, and are featured in many BSM models. Considering scalars produced in core-collapse supernovae allows one to extend sensitivity to far smaller couplings than can be probed at accelerators, which are fundamentally limited by luminosity. However, existing supernova bounds have left a substantial gap relative to accelerator constraints. I will present improved bounds on CP-even scalars that close this gap and extend the bounds to even lower couplings, combining an updated treatment of the trapping regime with new constraints derived from the visible products of scalar decays --- specifically the galactic 511 keV positron flux and energy deposition in low-energy supernovae. Together, these probes reach mixing angles as small as $\sin\theta \sim 10^{-9}$, more than five orders of magnitude below current collider limits, covering over nine orders of magnitude in coupling when combined with accelerator searches. I will also briefly present the extension of these results to a hadrophilic scalar model.

Speaker: Gustavo Marques-Tavares (University of Utah)

marquestavares_mitchell26.pdf

37 Searching for Ultralight Dark Matter with Pulsar Timing

Pulsar timing array experiments use high-precision timing of millisecond pulsars in the Milky Way to search primarily for nHz-frequency gravitational waves. Timing data is also sensitive to the presence of ultralight dark matter (ULDM) in the Galaxy: the ultralight field behaves as a classically oscillating wave that creates metric perturbations, imprinting a deterministic oscillatory signature in the pulse times of arrival. If ULDM is coupled to the Standard Model, it can also induce an oscillatory variation of fundamental constants that affect the pulsar rotational period and/or the atomic clocks used to establish times of arrival. The coherence region of oscillation varies with the ULDM mass, and existing analyses do not properly account for spatial correlations of the ULDM signal. In this talk, I will present the theoretical ground work and the first practical implementation of a self-consistent analysis of ULDM for pulsar timing.

Speaker: Prof. Kimberly Boddy (University of Texas at Austin)

kboddy-Mitchell-2026.pdf

38 Neutron Star Eclipses as Axion Laboratories

Axion-like particles (ALPs) appear in many beyond-the-Standard-Model theories, either as candidates for dark matter or as partners of the axion that explains the apparent conservation of charge-parity symmetry, known as the strong CP problem. In this talk, I will present a novel method for probing ALPs using eclipsing binary systems which can serve as an astrophysical realization of light-shining-through-walls experiments. Such systems are composed of a neutron star that is bright in X-rays and a larger companion star, through which ALPs produced via conversion in the neutron star's magnetosphere can pass during the eclipse. The ALPs then partially reconvert into photons in the interstellar medium on their way to Earth, and the resulting X-rays are detectable by space observatories such as XMM-Newton.

Speaker: Vedran Brdar (Oklahoma State University (US))

Vedran.pdf

39 Discovering Isolated Neutron Stars with the Vera Rubin Observatory

Isolated neutron stars (INS) are the simplest kinds of neutron stars, but only seven have been discovered and confirmed. We show that in the near future, the Vera Rubin Observatory (VRO) will be able to identify new INS candidates. In this talk, we outline a proof of concept for predicting the signals from INS as seen by VRO, as well as a method for separating those signals from backgrounds. We show that there are opportunities not only for the discovery of new objects, but also for constraining the microphysics of degenerate nuclear matter.

Speaker: Shirley Li (UC Irvine)

Mitchell_Li.pdf

Lunch

Friday Afternoon: Friday Afternoon 1

Convener: Kevin Kelly (Texas A&M University)

40 The future of lepton flavor

The flavor puzzle remains one of the biggest open questions in particle theory and upcoming results from neutrino experiments will provide a large impact on its solution. While it is difficult to constrain many classes of leptonic flavor models at the moment, this will change in coming years as several yet unknown quantities will be measured with some precision. Combined with expected improvements on the absolute neutrino mass scale from the combination of cosmology data sets or beta decay endpoint spectrum measurements will lead to a refined picture of our understanding of flavor in the lepton sector.
Here I will show how flavor model predictions relate to expected measurements and discuss correlations, degeneracies, and discrimination capabilities in the context of the expected measurements from upcoming experiments.

Speaker: Julia Gehrlein (Colorado State University (US))

flavor_mitchell.pdf

41 Antineutrino Signals of Ultralight Vector Dark Matter

Neutrinos oscillate into antineutrinos in a background of ultralight vector dark matter coupled to lepton number, such as the gauge boson of B-L. This effect is suppressed by the small neutrino mass, but the enhancement by long astrophysical baselines can enable uncharted parameter space to be explored by future searches for solar and supernova antineutrinos. For instance, the observation of a supernova neutrino burst at DUNE and Hyper-Kamiokande would probe new regions of parameter space for B-L dark matter that are beyond the capability of other future proposals.

Speaker: Asher Berlin (Fermilab)

Berlin_TAMU.pdf

42 Open system approach to neutrinos propagating in an ultralight scalar background

We examine decoherence in neutrino oscillations induced by an ultralight scalar field coupled to neutrinos. The scalar induces time- and position-dependent shifts in the neutrino mass matrix. Neutrinos sample different field configurations throughout an experimental data-taking period, which leads to damping effects in the oscillation pattern in the form of decoherence. By recasting the neutrino-scalar dynamics within the open quantum systems framework, we establish a mapping between a complete model and phenomenological decoherence approaches. We find that the parameter driving decoherence scales as $L^2/E^2$, where $L$ is the baseline and $E$ is the neutrino energy, as opposed to $L/E$ typically assumed in phenomenological studies of open system approaches to neutrino oscillations.

Speaker: Gustavo Alves

Alves_Gustavo_Mitchell_2026.pdf

43 Signatures of not-so-cold dark matter

If dark matter is not completely cold, the random motions of dark matter particles erase density fluctuations on scales smaller than their free-streaming length. This suppression contributes to the cosmological upper bound on the sum of the neutrino masses, which is uncomfortably close to the minimal value allowed by measurements of neutrino oscillations. It would seem that reducing the cosmological neutrino abundance by injecting photons after neutrino decoupling would loosen this constraint, but I will show that the unintended consequences of such a modification make the cosmological bound on the neutrino masses surprisingly robust. I will also present an alternative approach to computing how dark matter free streaming suppresses the matter power spectrum that is faster and more computationally stable than solving a truncated Boltzmann hierarchy. This new method also helps us understand what the matter power spectrum can reveal about the thermal history of dark matter.

Speaker: Adrienne Erickcek

Mitchell26_erickcek.pdf

Coffee Break

Friday Afternoon: Friday Afternoon 2

Convener: Nikita Blinov (York University)

44 General Chiral Couplings and the X17

In recent years, the ATOMKI collaboration has performed a series of measurements of excited nuclei, observing a resonant excess of electron-positron pairs at large opening angles compared to the Standard Model prediction. The excess has been hypothesized to be due to the production of a new spin-1 or spin-0 particle, X17, with a mass of about 17 MeV, implying a possible fifth force. Recently, the PADME experiment has reported an excess in the $e^+e^-$ cross section at center-of-mass energies near 17 MeV, perhaps further hinting at the existence of a new state. Studies of the spin-1 case have hitherto focused on either vector or axial-vector couplings to quarks and leptons, whereas UV theories more naturally produce both vector and axial-vector (i.e. chiral) couplings, analogous to the Standard Model weak interactions. We consider the ATOMKI anomalies in the context of an $X$ with chiral couplings to quarks and explore the parameter space that can explain the ATOMKI anomalies, contrasting them with experimental constraints. We find that it is possible to accommodate the reported ATOMKI signals. However, the $99\%$ CL region is in tension with null results from searches for atomic parity violation and direct searches for new low mass physics coupled to electrons. This tension is found to be driven by the magnitude of the reported excess in the transition of $^{12}{\rm C}(17.23)$, which drives the best-fit region towards excluded couplings.

Speaker: Dr Toni Makela (University of California, Irvine)

general_chiral_couplings_X17.pdf

45 Composite Ultralight Scalars, Fifth Forces, and Atomic Clocks

I discuss fifth forces mediated by an ultralight scalar that arises as a composite pseudo-Nambu-Goldstone boson from a strongly coupled hidden sector. In this framework, the scalar couples to the Standard Model through the hypercharge portal, and its interactions are softened above the compositeness scale by form factors. This can significantly weaken the bounds from equivalence principle (EP) tests when the compositeness scale lies between the atomic and nuclear scales. We find that clock-based searches can become the most sensitive probe of this scenario, with atomic clocks already competitive with traditional EP tests in certain regions of parameter space. These results highlight atomic clock experiments as a powerful, broadly motivated approach to searching for fifth forces.

Speaker: Zackaria Chacko (University of Maryland, College Park)

fifth_force_composite_Mitchell.pdf

46 Novel Signals from a Couple of Portals

Portal models, where new physics lives in a hidden sector neutral under the SM gauge groups provide a relatively weakly constrained way to extend the SM at the GeV-to-TeV scale. In this talk I will focus on some novel experimental signatures of the neutrino portal to a non-minimal hidden sector, as well as the phenomenology of a Z-prime model coupled to a non-anomalous and flavor-universal current in the SM.

Speaker: Can Kilic

Kilic portals Mitchell 2026.pdf

Conference Dinner

Sat, May 30

Saturday Morning: Saturday Morning 1

Convener: Prof. Kimberly Boddy (University of Texas at Austin)

47 Signatures of Composite Quarks and Leptons

A confining $SU(15)$ chiral gauge theory has recently been proposed in which the Standard Model fermions and Higgs emerge as composite bound states. After reviewing the model and the proton-decay constraints that place its compositeness scale in the $10^3$–$10^5$ TeV window, I will discuss the flavour signatures that the same dynamics predicts: a benchmark fit reproduces the SM masses and CKM matrix at per-mille accuracy and identifies $\epsilon_K$, the electron EDM, and $\mu$–$e$ processes as the leading low-energy probes.

Speaker: Benoit Assi (Fermilab)

Mitchell-Assi.pdf

48 Machine Learning Does It and Does It Better: Unearthing Primordial Dark-Matter Velocities from the Matter Power Spectrum

One effective way of learning about the production and properties of dark matter in the early universe is by extracting information about the primordial dark-matter phase-space distribution from the matter power spectrum. Recently a simple empirical formula was introduced which is capable of reproducing most of the salient features of the dark-matter phase-space distribution — even in situations in which this distribution is non-thermal, multi-modal, or exhibits other complicated features. In this talk, I examine the extent to which machine-learning techniques can improve upon this analytic approach and demonstrate that these techniques not only succeed in reconstructing the dark-matter phase-space distribution with greater accuracy, but are also applicable to a broader range of matter power spectra.

Speaker: Brooks Thomas

Mitchell-Conference-2026 (20 minutes).pdf

49 Dark Matter During First-Order Phase Transitions

We consider a dark sector consisting of fermionic dark matter (DM) charged under a broken dark $U(1)_D$ gauge symmetry, interacting with the Standard Model through kinetic mixing. In such models, the DM annihilation cross section is typically suppressed by the small kinetic mixing and or a heavy mediator, often leading to an overabundant relic density. We show that the observed DM abundance can be achieved if the dark Higgs undergoes a strong first order phase transition after DM freeze-out. In this scenario, the relic abundance is set by thermal freeze-out in the symmetric phase and subsequently reduced by entropy injection from the phase transition, rather than by annihilation in the broken phase. We find that to reproduce the observed relic abundance, the required phase transition is generically supercooled. The resulting stochastic gravitational wave signal lies within the sensitivity of future experiments, providing a complementary probe of this framework. Moreover, a strongly supercooled phase transition can potentially account for the NANOGrav signal for DM masses below $O(10)$ GeV.

Speaker: Peisi Huang

Huang.pdf

50 Searching for Ultraheavy Dark Matter with Magnetically Levitated Sensors

There are numerous theoretical candidates for dark matter significantly heavier than the WIMP scale ($\sim 100$ GeV), yet such models are less explored by experimental efforts. In this talk, I will discuss our progress searching for ultraheavy dark matter above 1 PeV in mass using a magnetically levitated setup with a 0.3 mg test mass and less than 100 aN/$\sqrt{\text{Hz}}$ of force noise. I will present the estimated sensitivity and discuss our on-going experimental campaign and data analysis. We expect to have leading sensitivity in parts of the parameter space, and our work represents the first time a maglev sensor is being used to search for ultraheavy dark matter.

Speaker: Dr Juehang Qin

Searching for Ultraheavy Dark Matter with Magnetically Levitated Sensors.pdf

Coffee Break

Saturday Morning: Saturday Morning 2

Convener: Peisi Huang

51 Light KK Gravitons from Extended Warped Extra Dimensions at DUNE

We study extended warped extra-dimensional models in which gravity propagates to a deep infrared brane with warped scale $\Lambda_{IR} \sim \mathcal{O}(\mathrm{MeV})$, leading to a dense KK graviton tower with MeV-scale spacing. We present a DUNE-motivated model realization of the photon portal to this tower. The visible electroweak gauge sector extends to an intermediate GeV brane, and brane-localized kinetic terms are used to control precision-electroweak constraints while preserving an enhanced coupling between KK gravitons and the photon. Primakoff-like production at DUNE then can produce GeV-scale KK gravitons, which then cascade down the tower to the lightest mode. If the radion channel is kinematically closed for the terminal state, the lightest KK graviton becomes long lived and decays visibly to diphotons. We discuss the resulting rich phenomenology of production, cascade decays, and signals at DUNE, and outline the main theoretical and precision constraints relevant for this extended warped scenario.

Speaker: Ankur Verma (University of South Dakota)

Mitchell_Ankur.pdf

52 Atmospheric CP Violation Probes

We propose a new approach to measure the CP-violating phase in neutrino mixing using atmospheric neutrinos, improving upon prior work. Because it is subject to systematic uncertainties that differ from those affecting accelerator-based measurements, the two approaches are complementary, and their combination can yield stronger constraints on δ₍CP₎. In particular, the differing energy ranges, baselines, and matter effects provide sensitivity that is not fully shared between the two methods. Realizing this potential will require further, but feasible, reductions in theoretical uncertainties. If achieved, this framework would provide an independent and robust probe as the next generation of neutrino experiments comes online to search for signals of CP violation.

Speaker: Stephan Meighen-Berger (University of Iowa)

2026_CP_Slides_Mitchell.pdf

53 Kaon Factories and Vectors Coupled to Non-conserved Currents

We study rare three- and four-body kaon decays as a probe of light vector and axial-vector bosons coupled to non-conserved currents. We find that searches for $K_L \to \pi^0 \pi^0 (X\to e^+e^-)$ decays constrain the couplings of light $X$ bosons to light quarks to be as small as $\mathcal{O}(10^{-5})$. The charged-pion modes $K^+ \to \pi^+ \pi^0 (X \to e^+e^-)$ and $K_L \to \pi^+ \pi^- (X \to e^+e^-)$ provide weaker limits, but constrain complementary combinations of couplings to the $u$, $d$, and $s$ quarks at the level of $\mathcal{O}(10^{-4})$. Finally, we also find that double emission of $X$ in $K \to \pi XX$ decays can provide yet additional constraints on the parameter space of light $X$ bosons due to a double $(m_K/m_X)^2$ enhancement to the rate. For a 17 MeV boson, these limits add to the known tension between spin-1 bosons coupled to vector and axial-vector currents interpretations of the results of the ATOMKI experiment with meson decay data. Finally, we also comment on negative pion capture on hydrogen and deuterium as a source of light particles and discuss the prospects for testing the 17 MeV boson hypothesis.

Speaker: Adrian Thompson

kaons_mitchell.pdf

54 Closing

Speaker: Kevin Kelly (Texas A&M University)