The energy budget of cosmological firstorder phase transitions beyond the bag equation of state
Abstract
The stochastic gravitationalwave backgrounds (SGWBs) from the cosmological firstorder phase transitions (FOPTs) serve as a promising probe for the new physics beyond the standard model of particle physics. When most of the bubble walls collide with each other long after they had reached the terminal wall velocity, the dominated contribution to the SGWBs comes from the sound waves characterized by the efficiency factor of inserting the released vacuum energy into the bulk fluid motions. However, the previous works of estimating this efficiency factor have only considered the simplified case of the constant sound velocities in both symmetric and broken phases, either for the bag model with equal sound velocities or νmodel with different sound velocities in the symmetric and broken phases, which is unrealistic from a viewpoint of particle physics. In this paper, we propose to solve the fluid EoM with an iteration method when taking into account the soundvelocity variation across the bubble wall for a general and realistic equation of state (EoS) beyond the simple bag model and νmodel. We have found a suppression effect for the efficiency factor of bulk fluid motions, though such a suppression effect could be negligible for the strong FOPT, in which case the previous estimation from a bag EoS on the efficiency factor of bulk fluid motions still works as a good approximation.
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 October 2022
 DOI:
 10.1088/14757516/2022/10/047
 arXiv:
 arXiv:2206.01148
 Bibcode:
 2022JCAP...10..047W
 Keywords:

 cosmological phase transitions;
 particle physics  cosmology connection;
 physics of the early universe;
 High Energy Physics  Phenomenology;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 General Relativity and Quantum Cosmology
 EPrint:
 34 pages, 9 figures