Seminarium "Teoria cząstek elementarnych i kosmologia"

According to the Higgs mechanism, violation of the electroweak symmetry is the reason particles we observe have non-zero masses. In the early universe thermal corrections restore this symmetry and we investigate the dynamics of its breaking. We focus on models predicting a first order phase transition proceeding through nucleation of bubbles. Such transitions are known to be able to facilitate production of the observed baryon asymmetry through electroweak baryogenesis as well as leaving a gravitational wave signal which will be one of the prime targets of upcoming GW experiments.We find that only weak transitions can result in slow expansion of the symmetry breaking bubbles for which we can test baryogenesis. For stronger transitions we never find the plasma is able to slow down the wall sufficiently to predict successful baryogenesis as the fluid approximation we employ breaks down. We find the weak transitions typically produce GW signals too weak to be observed in LISA which leads us to conclude that visible signals are likely to only be produced in strong transitions with highly relativistic wall velocities thus despite progress the tension between baryogenensis and strong GW signal remains. Finally, we also provide a simple analytical approximation for the wall velocity which only requires calculation of the strength and temperature of the transition and works reasonably well in all models tested.

slides: https://mycloud.fuw.edu.pl/index.php/s/5EfkZpMqWDJo6AK