Scientific Series

The gravitational memory problem is typically phrased in terms of the failure of constructing a (separable) Hilbert space for radiative gravitational modes at null infinity containing distinct memory states. There is, in a sense, a classical version of this problem: so far, there is no completely…

GW250114, with a signal-to-noise ratio of ∼80, enables the most precise single-event tests of strong-field gravity to date: setting the tightest constraints on deviations from general relativity, delivering the cleanest ringdown measurement yet, and placing stringent bounds on compact object…

Non-invertible symmetries have received a lot of attention in the last few years, with nontrivial applications in both high energy physics and condensed matter physics. I will discuss exact realizations of non-invertible symmetries on the lattice. Specifically, I will present a tensor network…

As particle physicists we usually think about small fluctuations of fields, but the phenomenology of our theories can depend crucially on the global structure of the symmetries and the topology of field space. First I'll discuss an ambiguity in the Standard Model gauge group, whose different…

Current pulsar timing array (PTA) analyses do not take full advantage of pulsar distance information, thereby missing out on improved angular resolution and on a potential factor-of-two gain in detection sensitivity for individual gravitational-wave (GW) sources. In this work, we investigate the…

In classical systems, the Kolmogorov–Arnold–Moser (KAM) theorem establishes that resonant tori of integrable Hamiltonians are destroyed by any nonintegrable perturbation, whereas nonresonant tori are only deformed up to a finite value of the perturbation parameter. In this seminar, we explore a…

Semisimple categorical symmetries, and their physical implications have been studied in great detail in the continuum and on the lattice. In particular, the nice properties of semisimple categories allows one to construct hamiltonians which enjoy this symmetry, and study its symmetric gapped phases…

The conformal bootstrap has been extremely successful for simple critical systems such as the 3D Ising model and vector models, where it has led to very precise determinations of critical exponents. However, obtaining similarly reliable nonperturbative data for more complicated theories, especially…

In this talk, I will formulate a new class of primordial perturbations called kinetic isocurvature perturbations, where the mass density of dark matter is constant relative to the photon number density while the kinetic energy of dark matter fluctuates in space. Such perturbations naturally arise in…