FORMATION AND SURVIVAL OF ELECTROWEAK-SYMMETRIC NUGGETS IN THE EARLY UNIVERSE

Abstract

It is well established that electroweak symmetry is restored at high temperatures. As the Universe expands, it cools in the EWS phase until it reaches a critical temperature TC at which the broken phase also becomes favored. If the phase transition is first order the Universe always supercools and the bubbles of the broken phase start expanding and then coalesce till the entire Universe is filled with the broken phase. The baryons, however, prefer to remain in the EWS phase because of their zero mass in the symmetric phase, and thus isolated bubbles of the symmetric phase could have remained, which would then be stabilized by the surface tension at the time of formation and would shrink because of the vacuum energy difference. These nuggets normally will not survive and will die out either by evaporation from the surface or by bubble nucleation of the broken phase. We study their properties at the time of formation and their evolution and survival as the Universe cools to its present epoch. We estimate the maximum number of baryons that have to be present in the nugget for it to survive till the freezeout temperature.