Triangle Seminars

Abstract:
Explaining the matter antimatter asymmetry of the universe requires a source of baryon number violation.
Baryon number is efficiently violated in the Standard Model of particle physics  at high temperature through  electroweak vacuum transitions,  the so-called sphaleron processes, which play a key role  in essentially all models of baryogenesis, whether at the electroweak scale or well beyond, as in leptogenesis.
I will show that these transitions can also be induced at zero temperature for large departure from equilibrium of the Higgs field.
In particular, we compute the rate of baryon number violation at T=0 arising from Higgs bubble collisions during a strong first-order electroweak phase transition. This opens up the possibility for a new mechanism of electroweak baryogenesis in the supercooled limit.

Abstract:
Conformal defects break part of the symmetry of a bulk CFT. The broken Ward identities lead to very general sum rules on the defect CFT data as well as on the data of bulk operators in the presence of a defect. We call these sum rules "defect soft theorems", and they hold generally for defects which break conformal symmetry, flavor symmetry, or supersymmetry. In this talk I will focus on line defects for which we can rewrite the constraints in dispersive sum rule form, and show how the defect soft theorems impose constraints on the defect spectrum and OPE coefficients.

This talk is based on https://arxiv.org/pdf/2509.26561 with B. Girault and M. Paulos, and on work in progress with G. Bliard, J. Julius, M. Paulos and N. Suchel.

Abstract:
The dynamics of QCD, unlike QED and gravity, is predominantly quantum in nature. We outline how a semi-classical regime emerges in the high energy Regge limit of the theory, where the dynamics is described by Yang-Mills equations, and multi-particle production is described by shockwave scattering. We demonstrate that trans-Planckian scattering in Einstein gravity can be understood similarly, with emergent double copy structures in gravitational radiation. We discuss possible consequences of this IR <-> UV correspondence in the two theories.

Abstract:
In this talk, we will present a unified Fermi-gas framework for computing BPS observables in ABJM theory on S^3. Supersymmetric localization reduces the problem to an interacting matrix model that can be interpreted as a one-dimensional ideal Fermi gas, whose dynamics is encoded in a set of TBA-like equations. We will show that these equations enable a non-perturbative bootstrap approach that systematically captures the instanton sectors of the free energy and winding Wilson loops. As applications, we will provide an analytic proofs of several previously conjectural formulas and derive closed-form expressions, valid at arbitrary winding number, for the leading membrane- and worldsheet-instanton corrections to the 1/6- and 1/2-BPS Wilson loops.

Abstract:
I will present a first principles rigorous derivation of gravitational charges in de Sitter using (suitably adapted version of) Noether’s theorem, and show that they satisfy a flux-balance law. The variational problem in de Sitter gravity requires that one specifies a conformal class up to diffeomorpshisms at future and past infinity. Gravitational radiation is possible only when the conformal class is non-trivial. I will illustrate the discussion with several exact solutions, including the radiative Robinson-Trautman-dS solution, which I will use to demonstrate the existence of conserved charges even in the absence of asymptotic (conformal) Killing vectors, and also the existence of monotonic charges, charges that are not conserved but rather change monotonically under time evolution. An example of a monotonic change is the Bondi mass.