Gravitational waves (GWs) produced during a first-order phase transition are a favourite candidate as a probe of beyond the standard model physics at future space-based experiments. The spectrum of produced GWs depends strongly on the terminal velocity at which bubbles of the broken phase expand in the plasma, and in particular on whether this velocity can become ultrarelativistic.
In this...
Focusing on supercooled phase transitions in models with classical scale symmetry, we investigate the limitations of derivative expansions in constructing a thermal EFT description for bubble nucleation. We demonstrate that derivative expansions for gauge field fluctuations diverge after the two leading orders because the gauge field mass varies strongly between the high- and low-temperature...
