Research

Protons and neutrons (collectively, hadrons) are the building blocks of everything around us, yet their internal structure remains an enigma. We can pull an atom out of a molecule and from that atom isolate a proton, but inside that proton, quarks and gluons are almost inextricably confined, making them challenging to study. One key goal of my work is to map out the complicated, intricate inner quark and gluon structure of hadrons.

Everyday substances come in three phases: solid, liquid, and gas. Quark/gluon matter also comes in phases. We typically see quarks and gluons confined in hadrons. However, under extreme temperatures or pressures, quarks and gluons can break free from hadrons and form new phases of matter like quark-gluon plasma. One objective of my work is to map out the phases of quark/gluon matter and how they transition into one another as we vary temperature and density. This area has many synergies with condensed matter.

When you turn on a flashlight, a beam of white light illuminates the wall in front of you. When you shine that same light through a glass prism, a rainbow comes out. The field of optics explores the principles behind how light waves propagate through various materials and are impacted by electromagnetic forces. One of my interests is developing techniques that help us better harness the power of time-periodic (Floquet) driving forces to control wave systems.  

Overview

Diffractive processes comprise nearly half the cross-section at the Large Hadron Collider and are a key probe of phenomena ranging from Regge (forward) physics, to the behavior of cosmic ray showers, to the saturation of nuclear matter. Diffractive processes exhibit unique properties, like forward scattering and large ​“rapidity gaps” of the detector devoid of particles, that have so far defied a systematic field theory description. We use effective field theory techniques to describe diffraction from first principles, opening up new frontiers for exploration at the dawn of the Electron-Ion Collider (EIC), High-Luminosity Large Hadron Collider (HL-LHC) and Facility for Antiproton and Ion Research (FAIR) accelerators.

Links

• Article on factorization of diffraction

• Seminar on diffraction, May 2025

Overview 

In the coming years, the FAIR accelerator will come online at GSI, opening up a new window into QCD phase structure. Now is the time to develop a better understanding of what the CBM experiment at FAIR may find, with particular attention to signals of new physics. Lattice simulations can provide us first-principles information about QCD at zero density, but at nonzero density a sign problem arises from non-Hermiticity of the Dirac operator, obstructing progress. We bring insights from the field of non-Hermitian physics (which is widely studied in optics and condensed matter) to bear on nuclear and particle physics, helping us develop new analytic and numerical tools for QCD phase structure. We show how in the vicinity of a critical point, non-Hermiticity can give rise to a "moat regime,'' a term that originates in condensed matter. We propose experimental signatures for these phenomena at FAIR.

Links

• Article on signatures of exotic phases

• Article on Z3 spin and gauge models

• Article on pattern formation

• Seminar for non-Hermitian physicists

• Seminar for a general physics audience

Overview

Transverse momentum distributions (TMDs) encode the 3D momentum structure of quarks and gluons inside hadrons. TMD fits to experimental data exhibit large uncertainties for non-perturbative parton momenta, a kinematic region which lattice QCD is typically well-positioned to probe. Unfortunately, TMDs are defined by time-dependent Wilson lines, causing a sign problem, an obstacle to numerics that is NP (exponentially) hard in general. To circumvent this issue, one can define a new lattice-calculable quasi-TMD by projecting the original Wilson lines onto a time-independent slice. We derive a factorization formula connecting these quasi-TMDs to physical TMDs. This formula holds at leading power, to all orders in αs, and for all spins and parton flavors. This factorization establishes that lattice and physical TMDs share the same underlying physics, and opens the path towards computing gluon TMDs.

Links

• Article on lattice TMD factorization

• Seminar on TMDs, October 2022

Overview

Energy correlators are a class of observables that are of wide interest in collider physics due to their compelling theoretical properties, their novel features for experimental studies, and the breadth of physical information they encode, ranging from the value of the QCD coupling constant αs to the behavior of TMDs. We significantly improve the theoretical prediction of the two-point energy correlator (EEC) by removing its leading renormalon, a type of singularity that causes poor perturbative convergence and provides information on nonperturbative effects. Our results lay the groundwork for improving predictions of related correlators and the precision of the physical information we extract from these observables.

Links

• Article on renormalons in the EEC

Overview

In Floquet engineering, we apply a time-periodic modulation to change the effective behavior of a wave system. We generalize Floquet engineering to more fully exploit spatial degrees of freedom, expanding the scope of effective behaviors we can access. We develop a perturbative procedure to engineer space-time dependent driving forces that effectively transform broad classes of tight-binding systems into one another. We demonstrate several applications, including removing disorder, undoing Anderson localization, and enhancing localization to an extreme in spatially modulated waveguides. This procedure straightforwardly extends to other types of physical systems and different Floquet driving field implementations, and we foresee its use in a range of atomic, optical, and condensed matter systems.

Links

• Article on Floquet engineering