Non-equilibrium effective field theory for early-universe cosmology

by Thomas Colas

Wednesday 28 Oct 2026, 11:30 → 12:30 Europe/Zurich

4/2-011 - TH common room (CERN)

Dissipation and noise arise when observable degrees of freedom interact with an environment, from condensed matter systems to the early universe. The Schwinger–Keldysh formalism provides a systematic framework for incorporating these effects into effective field theory. In this talk, I present a cosmological approach that combines general relativity with this framework. Drawing on techniques developed in fluctuating hydrodynamics, I show how symmetry, locality, and unitarity constrain dissipation and noise, and how these effects can generate distinctive signatures in primordial non-Gaussianity. I then discuss the radiative stability of these theories and the prospects for extending this approach to non-thermal fixed points and far-from-equilibrium dynamics in cosmology.