General information:

1. The seminar usually takes place in person at Knudsen 5-142 and sometimes via Zoom.
2. For other related seminars hosted by the UCLA Department of Physics & Astronomy, please refer to the department events page: Department Events.
3. We also actively participate in seminars offered by the Nuclear Science Division at Lawrence Berkeley National Laboratory: Hadron Ion Tea (HIT).
4. For travel information, including flights, directions, and parking, please visit our Visiting page.
5. For seminars in previous years, please refer to:
2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017

06/12/2026

Positive Smeared Matrix Elements at NLO

Andrew Larkoski, APS
12:00 PM Friday, Knudsen 5-142

The issue of negative weights in the simulation of particle collider events at higher orders in perturbation theory can significantly reduce numerical precision, for a given statistical sample size. Several methods for reducing negative event weights have been proposed, including resampling techniques that involve summing or "smearing over" nearby events on phase space to ensure positivity. Such methods have typically used machine learning algorithms to perform the resampling of the data ensemble, but effectively use no physics to inform it. In this talk, I will introduce an event smearing algorithm that exploits the universality of soft and collinear divergences in quantum chromodynamics, explicitly calculating all necessary components at next-to-leading order.

06/08/2026

One Point Charge Correlations in Deep-Inelastic Scattering

Haotian Cao, Northwestern
11:00 AM Monday, Knudsen 5-142

In this talk, I will present a charge correlation observable in deep-inelastic scattering, defined as the charge deposit measured at a fixed polar angle relative to the incoming proton. Using soft-collinear effective theory, we derive factorization theorems for both the target and current fragmentation regions. In the forward limit, the nucleon charge correlator encodes detailed nucleon structure, while in the back-to-back limit the observable reduces to standard TMD factorization. This establishes a charge-and-angle measurement paradigm for spin physics at a future Electron-Ion Collider.

05/20/2026

Real-time correlation functions on ancilla-free quantum computers

Xiaoyang Wang, RIKEN
3:30 PM Wednesday, Knudsen 5-142

The n-time correlation function is pivotal for establishing connections between theoretical predictions and experimental observations of a quantum system. Conventional methods for computing n-time correlation functions on quantum computers generally require an ancilla qubit that controls the entire system -- an approach that poses challenges for digital quantum devices with limited qubit connectivity, as well as for analog quantum platforms lacking controlled operations. Here, we introduce a method to compute n-time correlation functions using only unitary evolutions on the system of interest, thereby eliminating the need for ancillas and the control operations. We demonstrate our protocol on IBM quantum hardware up to 12 qubits to measure the single-particle spectrum of the Schwinger model and the out-of-time-order correlator (OTOC) in the transverse-field Ising model, where the noiseless simulation results are successfully reproduced from the noisy hardware. Additionally, I will talk about our recent work on predicting the long-time dynamics of the correlation function from its short-time training data.

05/13/2026

Decoherence in high energy collisions

Dingyu Shao, Fudan University
3:30 PM Wednesday, Knudsen 5-142

In this talk, I present a new framework for calculating spin decoherence due to final-state radiation by merging soft-collinear effective theory with the open quantum system formalism. Our central discovery reveals that the renormalization group evolution of the density matrix is naturally interpreted as a quantum channel, wherein the flow of energy scales governs a Markovian loss of quantum information. This insight enables us to derive the first analytical, all-orders prediction for entanglement suppression as a function of detector resolution. By directly linking the resolution of an experimental apparatus to the preservation of coherence, our work establishes a rigorous theoretical tool for quantifying and controlling quantum information at the energy frontier.

04/13/2026

Axial vector form factors and the scalar charge of nucleons from lattice QCD

Rajan Gupta, LANL
11:00 AM Monday, Schwinger Lounge
Special TEP Seminar

This talk will motivate the need for large scale simulations of lattice Quantum Chromodynamics (lattice QCD) to calculate two phenomenologically interesting properties of nucleons: (i) the axial vector form factors needed for the analysis of neutrino oscillation experiments (in fact, we will ultimately need quantum computing), and (ii) the scalar charge--important to direct detection of dark matter experiments and in the pion-nucleon sigma term, an important parameter in nuclear physics. Today, with growing computing power and novel algorithms, lattice QCD is providing increasingly precise results at multiple values of the pion mass close to the physical one and on increasingly fine large volume lattices needed to control the chiral, continuum and finite volume (CCFV) extrapolation needed to match to experiments. A major additional systematic in these calculations is the contributions of excited states, especially multiparticle states such as the N\pi and N\pi\pi with the quantum number of the nucleons. A brief discussion of this systematic and methods pioneered by the Los Alamos team to understand and remove them will be given. The talk will conclude with a summary of the current state of the calculations and prospects for improvements.

03/22/2026 - 03/27/2026

The 22^nd International Conference on Strangeness in Quark Matter (SQM 2026)

Physics and Astronomy Building

02/25/2026

Eigen-microstate Signatures of Criticality in Relativistic Heavy-Ion Collisions

Yuanfang Wu, CCNU
11:00 AM Wednesday, Knudsen 5-142

We develop the eigen-microstate framework as a new approach to identify criticality in relativistic heavy-ion collisions. We construct the original microstate, defined as the final-state particle fluctuations of a single event. By examining ensembles of such original microstates with and without critical signals, we demonstrate that the corresponding eigen-microstate can extract and reveal the dominant critical mode, with the largest eigenvalue serving as a robust order parameter. We also present a comprehensive model study of the eigen-microstate approach (EMA) for identifying critical fluctuations in relativistic heavy-ion collisions. Using UrQMD and two stochastic baseline models, we demonstrate that EMA is insensitive to conventional short-range correlations and effectively filters out non-critical backgrounds。These results demonstrate that EMA offers a robust and background-independent method for critical-point searches. This framework avoids equilibrium assumptions and the approach is directly applicable to RHIC Beam Energy Scan data, offering a powerful new tool in the search for the QCD critical point.

02/24/2026

The Structure of Quantum Resources in Fundamental Physics

William Munizzi, UCLA
1:00 PM Tuesday, Knudsen 5-142

Entanglement and magic are complementary quantum resources that constrain the computational power of quantum systems, as well as the interactions they can fundamentally realize. In high-energy physics, these resources extend beyond computational measures: entanglement underlies emergent features of holographic dualities, black hole thermodynamics, and the organization of correlations across spacetime, while magic captures non-stabilizer structure, probing aspects of interacting field theories and quantum gravity that evade a semiclassical description. In this talk, I will discuss how entanglement and magic constrain physical phenomena in contexts such as AdS/CFT, particle interactions, and topological quantum field theories. I will also present mathematical techniques for bounding the dynamics of these resources, including an operator-level framework for tracking the generation of both under quantum evolution. Together with data-driven machine-learning methods, we develop a unified framework for studying how quantum information structure can impact emergent physics and quantum dynamics.

02/11/2026

AI-Accelerated Rare Event Search: From Optimization to Discovery

Aobo Li, UCSD
11:00 AM Wednesday, Knudsen 5-142

Rare event searches, including the experimental hunt for neutrinoless double beta decay and dark matter, address some of the most fundamental questions in physics. However, detecting these extremely rare signals requires overcoming significant computational and background challenges. This seminar highlights two of our recent AI-driven solutions designed to accelerate this field: surrogate modeling and time series denoising. First, I will present an uncertainty-aware surrogate modeling framework that replaces expensive simulations to enable fast detector optimization with rigorous uncertainty quantification. I will discuss its successful deployment in the LEGEND experiment, where it reduced neutron backgrounds by 66.7%, as well as its broader application in the COHERENT, XENONnT, and DUNE experiments. Second, I will introduce TIDMAD, a benchmark dataset for dark matter discovery, demonstrating how machine learning-based denoising algorithms can dramatically enhance signal sensitivity in realistic, noisy detector environments. Both works were recognized as Spotlight papers at top AI conferences.

01/27/2026

Recent Advances in Multimodal Foundation Models and Grounded Visual Reasoning

Bryan Zhou, UCLA
1:00 PM Tuesday, Knudsen 5-142

Over the past few years, transformers and autoregressive foundational models have revolutionized nearly every sub-field of machine learning, from language generation and speech processing to robotics control and video understanding. In this talk, I will first introduce the recent advancements in transformers and multimodal foundation model research, along with their applications and limitations. Then, I will discuss my recent work on training such multimodal foundation models and applying them for grounded visual reasoning, based on our recent paper SAM 3: Segment Anything with Concepts. I will also discuss post-training and reinforcement learning techniques to elicit agentic reasoning capabilities in multimodal large language models, as seen in SAM 3 Agent.

01/21/2026 - 01/23/2026

Quantum Winter School 2026: Quantum Simulation

Institute for Pure & Applied Mathematics