QSimFP FVD Seminar: Bubble velocities and oscillon precursors in first order phase transitions

Abstract: Metastable `false' vacuum states are an important feature of the Standard Model of particles physics and many theories beyond it. In this talk I will introduce new observables describing the dynamics of a phase transition out of a false vacuum via the nucleation of bubbles. We study vacuum decay at finite temperature by numerically evolving ensembles of field theories in 1+1 dimensions from a metastable state. We demonstrate that for an initial Bose-Einstein distribution of fluctuations bubbles form with a Boltzmann-distributed spread of centre-of-mass velocities and that bubble nucleation events are preceded by an oscillon - a long-lived, time-dependent, pseudo-stable configuration of the field. We describe why these features are theoretically expected, and find quantitative agreement between simulations and theoretical predictions. We directly measure the critical bubble configuration from simulations by stacking nucleation events in their rest frame, finding agreement with the theoretical prediction for the bubble solution. We compute the total energy of the stacked configuration and the prediction for the energy of the critical bubble given by the measured velocity distribution, and find good agreement in both cases with the expected energy of the theoretical critical bubble solution.

Bio: Dalila Pirvu is a graduate student in Cosmology at Perimeter Institute and University of Waterloo, Canada. She finished her undergraduate at Imperial College London. She works on lattice simulations of first order phase transitions in quantum field theories. She is also interested in dark matter and its interactions with large scale structure.