First order electroweak phase transition triggered by the Higgs portal vector dark matter

TL;DR

This paper explores a Standard Model extension with a new U(1)' gauge symmetry and a complex scalar, demonstrating conditions for a strong first order electroweak phase transition compatible with dark matter stability.

Contribution

It introduces a U(1)' extension with a scalar singlet and Z2 symmetry, showing it can support both dark matter and a strongly first order EWPT.

Findings

Parameter space supports dark matter stability and strong EWPT

Gauge independent method used for phase transition analysis

Model compatible with electroweak baryogenesis requirements

Abstract

We investigate an extension of the Standard Model (SM) with a U(1)' gauge symmetry, which is spontaneously broken by a complex scalar singlet and where the new gauge boson is a stable dark matter candidate via a Z2 flavor symmetry. The possibility of generating a strongly first order electroweak phase transition (EWPT) needed for the electroweak baryogenesis mechanism in this model is studied using a gauge independent method. Our result shows a considerable parameter space where both successful dark matter phenomenologies and a strongly first order EWPT can be achieved.