Electroweak phase transition in the presence of hypermagnetic field and the generation of gravitational waves

Abstract

We investigate the effects of a large-scale background hypermagnetic field on the electroweak phase transition (EWPT). We propose a model in which an effective weak angle varies during the EWPT and upon its use we show that, although for the majority of the parameter space the phase transition is a crossover, there are tiny regions in which the phase transition occurs in two steps and can be first-order. We obtain all of the important quantities characterizing the details of the first-order phase transition, including the latent heat, transition temperature and duration. We then calculate the gravitational wave energy spectrum generated during the first-order part of the EWPT and find that, for strong enough background hypermagnetic fields, these signals can be detected by the Ultimate-DECIGO interferometer.