PGSS 2026

PGSS Invited Faculty Lecture: Shedding Light on Dark Matter with Particle Accelerators

Christian Herwig

Assistant Professor, Department of Physics

What is the nature of dark matter (DM)? Thermal relics provide an excellent candidate, predicting DM masses within a few orders of magnitude of the proton, and small couplings to the known Standard Model (SM) particles. Particle accelerators are critical instruments in this search, where machines that achieve the highest energies and intensities are deeply complementary in exploring the full range of allowed masses. I will start by discussing a two-fold strategy that leverages datasets collected by the ATLAS Experiment at the Large Hadron Collider and the Light Dark Matter Experiment at the SLAC LCLS-II, before pivoting to a few recent developments and ideas for the future.

A Simple Quantum System With Universal Black Hole Features

Loki Lin

Department of Physics

Could a cloud of electrons in a magnetic field and a charged black hole ever look the same? Any sane person would say of course not -- one is an ordinary condensed-matter system, while the other is an exotic object in gravity. But under specific circumstances, they can share the same low-energy dynamics. In this talk we will set up the two sides of this correspondence. We will introduce the problem of black hole entropy and the idea of holography, argue that the near-horizon physics of charged black holes reduces to quantum gravity in two dimensions, and write down a simple quantum mechanical model of electrons on a sphere which surprisingly realizes the same spectrum as 2d quantum gravity. This is an example of universality: the fact that very different microscopic systems often end up behaving the same way when the details are blurred out. The talk is based on arXiv:2601.08908 with Anna Biggs and Juan Maldacena. We will assume knowledge of only undergraduate-level quantum mechanics and statistical mechanics.

How Deep Are the Cracks in Cosmology? Insights from DESI

Prakhar Bansal

Department of Physics

For more than two decades, the standard cosmological model, ΛCDM, has provided a remarkably successful description of observations ranging from the cosmic microwave background to the large-scale structure of the Universe. However, the increasing precision of modern surveys has revealed a number of intriguing anomalies, including the Hubble tension, hints of dynamical dark energy, and the cosmological constraints on neutrino masses. Determining whether these discrepancies are statistical fluctuations, unresolved systematics, or evidence for new physics has become one of the central challenges in cosmology. In this talk, I will discuss how recent measurements from the Dark Energy Spectroscopic Instrument (DESI) are helping to address these questions. I will present several complementary analyses that use DESI data to test extensions of ΛCDM and assess the significance of current cosmological tensions. I will also highlight ongoing efforts toward DESI full-shape analyses using joint power-spectrum and bispectrum measurements. Together, these studies provide a broad perspective on the current status of cosmological tensions and the extent to which DESI data support extensions beyond ΛCDM.

Why 3D Is So Frustrating: Understanding Structural Complexity Through Curved-Space Packings

Michelle Thran

Department of Physics

Whether synthetic or natural, nanoparticles in our three-dimensional universe self-assemble into structures with a remarkable degree of complexity. However, it is difficult to predict assemblies for all but the simplest shapes and pair potentials. Part of this challenge lies in the fact that most particle environments which are favored locally are incommensurate with the global geometry, a situation known as "geometric frustration". The purpose of this work is to study the extent to which this emergent complexity can be understood as resolved geometric frustration. Geometric incommensurability can be resolved by curving space; Curved spaces offer new compatible particle arrangements and can therefore “relax” geometric frustration in assemblies. In many cases, features of assembled structures can be interpreted as topologically necessary defects of curved-space assemblies.

Are Giant Gravitons the Atoms of Quantum Gravity?

Sabarenath Jayaprakash

Department of Physics

One of the most striking ideas in modern theoretical physics is that gravity in a curved spacetime can be secretly equivalent to a QFT living on its boundary. This equivalence, AdS/CFT, lets us study the same physics from two radically different perspectives. The superconformal index, a supersymmetry-protected fingerprint of a theory's spectrum, is an elegant tool for testing this. For a long time, matching was only understood in an idealized limit. The frontier is understanding what happens when this idealization is relaxed. 

I will show that corrections to the index have a beautiful gravitational interpretation. When a graviton carries too much angular momentum, it inflates into an extended object, a giant graviton, stabilized by its own spin. Quantizing these giants reduces to a harmonic oscillator problem, letting us directly count states and recover the index. I will close with a tantalizing idea: giant gravitons appear to be universal building blocks, independent of the field theory's details, suggesting black holes may be assembled from these fundamental gravitational atoms.

Bootstrapping Quantum Chromodynamics at Low-Energies

Aditi Chandra

Department of Physics

How much of what we see in the physical world is explained simply by consistency with quantum mechanics and special relativity? The bootstrap program is a recently revived effort to answer this question by carving out the space of allowed theories compatible with such basic physical principles. In this talk, we'll explore the bootstrap for quantum chromodynamics at low energies, the theory of the strong force. At low energies, the strong interactions are best described in terms of bound states of quarks and gluons - such as mesons - but this low energy theory cannot be derived from QCD perturbatively. Might the bootstrap help? In the talk, we'll explain how the bootstrap works, provide an introduction to QCD, and highlight what the bootstrap can teach us about the strong force. 

Imprints of Mass Accretion History on Galaxy Cluster Stellar Density Morphology

Kabelo Tsiane

Department of Physics

Variations in dynamical states of galaxy clusters can introduce biases and scatter in observable-mass relations and reduce detectability in cluster-finding algorithms. The dynamical state of a cluster is an emergent feature of its mass accretion history (MAH), it is therefore of interest to constrain the MAH of the cluster to account for these errors. In this talk, I will characterize 305 massive clusters from The300 project, connecting features from their projected stellar distributions to their mass accretion histories. As a baseline, I first connect host dark matter halo dynamical state indicators at z = 0 with their MAHs. I repeat this exercise with morphological measurements of projected stellar density maps. We further quantify the MAH prediction power using Multivariable Conditional Abundance Matching (MultiCAM), a novel framework for connecting galaxy/halo properties with their formation history. I conclude with example applications of my results, and future observational efforts with Rubin LSST and LoVoCCs.

Probing Ideal Quantum Wires in Topological Materials

Joseph Essman

Department of Applied Physics

Since the discovery of the quantum Hall effect in 1980, topological materials (defined by their bulk insulation and edge conductivity) have been one of the most active fields of research in condensed matter physics. The quantum Hall effect in particular exhibited "perfect" conduction along its edges, at a value so precise and reliable as to define the Ohm. These "ideal quantum wire" edge states are possible when electrons are forbidden from backscattering. In this talk, I discuss approaches to measuring two different systems featuring (or predicted to feature) such states: the fractional quantum Hall effect in graphene, and conducting dislocations in topologically insulating Bismuth Antimony Alloys. I will give a brief overview of the theory of both of these topics, as well as the fabrication and measurement methods necessary for transport measurements, and the preliminary data for these projects.

Ancient Minerals as Paleo-Detectors for Neutrino and Dark Matter Detection

Emilie LaVoie-Ingram

Department of Physics

The use of ancient minerals as “paleo-detectors” is a new experimental technique for neutrino and dark matter detection, preserving nuclear recoil damage tracks induced by these particles for upwards of a billion years. Competitive with real-time detection experiments, one milligram of crystal dated at one billion years old has the same exposure as a one ton experiment operating for one year. The Spitz Group at the University of Michigan looks for these defects in promising olivine and quartz crystal paleo-detectors, and works to navigate the challenges associated with using natural minerals and finding the microscopy needed to reach competitive exposure limits. This talk explores the physics behind damage formation in geological samples, the complexities of using paleo-detectors, and the impacts of material properties, depth, thermal history, and age on dark matter detection sensitivity.

Full speaker list coming soon!