Electroweak phase transition triggered by fermion sector

Abstract

To realize first-order electroweak phase transition, it is necessary to generate a barrier in the thermal Higgs potential, which is usually triggered by scalar degree of freedom. We instead investigate phase transition patterns in pure fermion extensions of the standard model, and find that additional fermions with mass hierarchy and mixing could develop such a barrier and realize a strongly first-order phase transition in such models. In the Higgs potential with polynomial parametrization, the barrier can be generated in the following two patterns by fermionic reduction effects: (I) positive quadratic term, negative cubic term and positive quartic term or (II) positive quadratic term, negative quartic term and positive higher dimensional term, such as dimensional 6 operator.

Global Electroweak Symmetric Vacuum

“…A lot of attention has been given to this ordinary EWPT story, because the EWPT could be a first-order one to realize the EW baryogenesis [11,12]. Recently, there has been also increased interests in exploring an alternative cosmological history of the universe [13][14][15][16][17], by reviving the old idea of SNR, which is also known as inverse symmetry breaking, where the EWPT doesn't occur at the temperature of the EW scale, but rather at a much higher temperature. There is an SNR in between them, such that the broken vacuum remains to be the one that the universe sits on even for the temperature much above the EW scale.…”

Electroweak phase transition triggered by fermion sector

“…We will discuss the different multi-scale effective potential among other renormalization schemes and several ways to get the effective potential at the LE scale in future work[17].…”