Electroweak phase transition in the MSSM with $U(1{)}^{\ensuremath{'}}$ in an explicit $CP$ violation scenario

Electroweak phase transition in the MSSM with $U (1)^{'}$ in an explicit $C P$ violation scenario

S. W. Ham and S. K. Oh

Phys. Rev. D 76, 095018 – Published 30 November 2007

Abstract

The possibility of a strongly first-order electroweak phase transition is established in the minimal supersymmetric standard model with an extra $U (1)^{'}$ , where a nontrivial $C P$ violating phase is introduced in its Higgs sector. We find that there is some region in the parameter space of the model that allows the strongly first-order electroweak phase transition. The mass of the stop quark need not be smaller than the top quark mass to ensure the first-order electroweak phase transition be strong. The effect of the $C P$ violating phase upon the strength of the phase transition is discovered. The strength of the phase transition is reduced when the size of the $C P$ violation is increased. For a given $C P$ violating phase, we find that the model has a larger mass for the lightest Higgs boson when it has a stronger phase transition.