QSimFP FVD Seminar: Bubble Clustering in Cosmological First Order Phase Transitions

Abstract: False vacuum decay in quantum mechanical first order phase transitions is a phenomenon with wide implications in cosmology and presents interesting theoretical challenges. In the standard approach, it is assumed that false vacuum decay proceeds through the formation of bubbles that nucleate at random positions in spacetime and subsequently expand. In our work, we investigated the presence of correlations between bubble nucleation sites using a recently proposed semiclassical stochastic description of vacuum decay. The procedure sampled vacuum fluctuations which were evolved using classical lattice simulations. We computed the two-point function for bubble nucleation sites from an ensemble of simulations, demonstrating that nucleation sites cluster in a way that is qualitatively similar to peaks in random Gaussian fields. I will comment qualitatively on the phenomenological implications of bubble clustering in early Universe phase transitions, which include features in the power spectrum of stochastic gravitational waves and an enhancement or suppression of the probability of observing bubble collisions in the eternal inflation scenario. I finish by explaining briefly how our results can be tested empirically using a table-top analogue of vacuum decay.

Biosketch: Dalila Pirvu is a second year PhD student at the Perimeter Institute and University of Waterloo in Canada. She did her undergraduate at Imperial College London. Her work is focused on dynamical lattice simulations of phase transitions in quantum field theories.

The seminar will last 1 hour including Q&A and be held at 3.00pm UK Time/10.00am Toronto Time.

This seminar will be held on Zoom. Details to follow