Electroweak phase transitions in the secluded U(1)-prime-extended MSSM

TL;DR

This paper investigates the electroweak phase transition in the secluded U(1)'-extended MSSM, identifying conditions for a strong first order transition and analyzing Higgs mass constraints and CP violation effects.

Contribution

It provides the first detailed analysis of the EWPT in the sMSSM, including parameter scans and Higgs mass limits for a strong first order transition.

Findings

Higgs boson masses compatible with strong EWPT are m_{H_1}<160 GeV and m_{A_1}<250 GeV.

Light stop mass can be larger than the top quark mass in this scenario.

CP violation at tree level does not hinder the strong first order EWPT.

Abstract

The electroweak phase transition (EWPT) in the secluded-$U(1)'$-extended MSSM (sMSSM) is studied. Using the effective potential at zero and finite temperatures, we search for the non-MSSM-like EWPT in which the light stop mass is larger than the top quark mass. Scanning the parameters relevant to the EWPT, the upper limits of the Higgs boson masses, which are consistent with the strong first order EWPT, are derived. For the lightest CP-even and -odd Higgs bosons, we find $m_{H_1}<160$ GeV and $m_{A_1}<250$ GeV, respectively. In the sMSSM, the tree-level CP violation is possible by the complex soft supersymmetry breaking masses. It is observed that such a CP-violating effect does not spoil the strong first order EWPT for the typical parameter sets.