17–21 Aug 2026
University of Helsinki Main Building
Europe/Helsinki timezone

Bubble Wall Velocity from Plasma Viscosity

19 Aug 2026, 16:20
20m
F4050 (4th floor) (University of Helsinki Main Building)

F4050 (4th floor)

University of Helsinki Main Building

University of Helsinki Fabianinkatu 33 Finland
poster Early universe physics, inflation, electroweak phase transitions, and sources for gravitational waves Poster Session

Speaker

Nicklas Ramberg (SISSA)

Description

We attempt to reformulate the problem of the microscopic friction force exerted on a bubble wall, focusing on strongly interacting plasmas. Across the confinement transition, the loss of a quasiparticle description renders a conventional kinetic theory approach challenging, so that assuming local thermal equilibrium (LTE) can provide an upper bound on the wall velocity by neglecting the additional friction from out-of-equilibrium effects. In this talk, we suggest a hydrodynamic framework for computing the friction force exerted on the bubble wall, grounded in viscous hydrodynamics, circumventing microphysical scattering calculations. We demonstrate the utility of this approach by applying it to a secluded pure SU(N) Yang-Mills sector undergoing the confinement FOPT, obtaining self-consistent estimates of the terminal bubble wall velocity.

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