Phase transitions and gravitational waves with supercooling

Models with classical scale invariance provide interesting candidates for GW signals from phase transitions, that could be observable with LISA. They typically feature a significant amount of supercooling, and correspondingly a very large phase transition strength. Computations of phase transition parameters often feature slow perturbative convergence, resulting in large errors. A remedy for this issue is to construct an appropriate effective theory for bubble nucleation, this is typically done in the framework of high-temperature dimensional reduction. In this talk, I discuss the first application of this procedure to a model with a large amount of supercooling, and compare the results to the frequently applied daisy-resummation. We will see that the gravitational wave predictions get affected significantly, confirming the importance of an appropriate use of effective field theories, including functional determinants for the gauge modes.