HYDRODYNAMIC STABILITY ANALYSIS OF BURNING BUBBLES IN ELECTROWEAK THEORY IN QCD

Assuming that the electroweak and QCD phase transitions are first orde r, upon supercooling, bubbles of the new phase appear. These bubbles g row to macroscopic sizes compared to the natural scales associated wit h the Compton wavelengths of particle excitations. They propagate by b urning the old phase into the new phase at the surface of the bubble. We study the hydrodynamic stability of the burning and find that for t he velocities of interest for cosmology in the electroweak phase trans ition, the shape of the bubble wall is stable under hydrodynamic pertu rbations. Bubbles formed in the cosmological QCD phase transition are found to be a borderline case between stability and instability.