Speaker
Description
First-order phase transitions are common in many beyond the Standard Model theories. Nucleating transitions are particularly interesting, since they leave behind a gravitational wave background (GWB) that could be observable in many near-future experiments. The nucleation rate determines how fast the transition completes and is needed for precision predictions of the GWB.
Typically, the metastable system is assumed to be spatially homogeneous. In contrast, in the seeded case the nucleation probability is locally enhanced by some impurity in the system, such as a topological defect. We consider a system of two scalar fields in two spatial dimensions with a domain wall as the impurity. The scenario is that of a two-step transition in which the first transition leaves behind a system of domain walls that in turn seed the second transition to the true vacuum.
For very slow nucleation the rate is estimated using multicanonical MCMC to determine the probability of critical bubble configurations. For faster nucleation, as in our case, we can simply evolve the system in time and wait for the nucleation to occur. We compare the simulation results to analytic estimates computed in a dimensionally reduced effective field theory living on the domain wall and find good agreement.