Strong First Order Electroweak Phase Transition in Gauge-Higgs Unification at Finite Temperature

TL;DR

This paper investigates the electroweak phase transition in a gauge-Higgs unification model at finite temperature, deriving a general 1-loop effective potential and demonstrating a strong first-order transition consistent with the observed Higgs mass.

Contribution

It introduces a general formula for the 1-loop effective potential at finite temperature using ζ function regularization, applicable to higher-dimensional flat space models.

Findings

A strong first-order electroweak phase transition occurs in the model.

The effective potential formula simplifies calculations by requiring only the Kaluza-Klein spectrum functions.

The model reproduces the observed 125 GeV Higgs mass and viable fermion hierarchy.

Abstract

We analyze the electroweak phase transition at finite temperature in a model of gauge-Higgs unification where the fermion mass hierarchy including top quark mass, a viable electroweak symmetry breaking and an observed Higgs mass are successfully reproduced. To study the phase transition, we derive the general formula of the 1-loop effective potential at finite temperature by using the $\zeta$ function regularization method. It is remarkable that the functions determining the Kaluza-Klein mass spectrum have only to be necessary in calculations. This potential can be applicable to any higher dimensional theory in flat space where one extra spatial dimension is compactified. Applying to our model of gauge-Higgs unification, the strong first phase transition compatible with 125 GeV Higgs mass is found to happen.