Bubble wall dynamics from nonequilibrium quantum field theory

by Matthias Carosi

Thursday 29 May 2025, 12:00 → 13:00 Europe/Madrid

IFAE Seminar Room (In-Person)

First-order phase transitions (FOPT) in the early universe are a unique probe of physics beyond the Standard Model, playing a key role in electroweak baryogenesis, the formation of primordial black holes, magnetogenesis and the production of dark matter. Future gravitational wave detectors will allow us to see the signature of possible FOPT, but to extract theoretical value from it, we need a precise understanding of their dynamics. In this talk, I demonstrate how the language of non-equilibrium quantum field theory, together with the two-particle-irreducible effective action, offers a natural framework to describe the dynamics of a bubble after nucleation. After a brief introduction to the closed-time-path formalism, I derive the dynamical equations for the bubble and the plasma, and identify all sources of friction for the bubble expansion. In the ultrarelativistic regime, I show how to derive the friction induced by the pair production of heavy scalar particles, and outline how the contribution of particle mixing and transition radiation can be obtained.