Spontaneous Violation of the CP Symmetry in the Higgs Sector of the Next-to-Minimal Supersymmetric Model

TL;DR

This paper investigates the spontaneous violation of CP symmetry in the Higgs sector of the NMSSM, deriving analytical formulas, exploring parameter space, and analyzing implications for Higgs masses and K-Kbar mixing.

Contribution

It provides analytical expressions for the 1-loop neutral Higgs mass matrix in the NMSSM with non-degenerate scalar-top quark masses, highlighting conditions for spontaneous CP violation.

Findings

Spontaneous CP violation can occur in the NMSSM Higgs sector.

The lightest Higgs boson mass upper bound is about 140 GeV.

CP violation impacts K-Kbar mixing bounds.

Abstract

The spontaneous violation of the CP symmetry in the next-to-minimal supersymmetric standard Model (NMSSM) is investigated. It is found that the spontaneous violation of the CP symmetry can occur in the Higgs sector of the NMSSM for a wide region of the parameter space of the model, at the 1-loop level where the radiative corrections due to the top quark and scalar-top quark loops are found to generate the scalar-pseudoscalar mixings between the two Higgs doublets of the NMSSM. In our model, we assume that the masses of the left-handed and the right-handed scalar-top quarks are not degenerate. And we investigate our model anaytically: We derive analytical formulae of the 1-loop mass matrix for the neutral Higgs bosons. We calculate the upper bound on the lightest neutral Higgs boson mass under the assumption. It is found to be about 140 GeV for our choice of parameter values in the presence of the spontaneous violation of the CP symmetry in the NMSSM. Thus, the possibility of the spontaneous violation of the CP symmetry is not completely ruled out in the Higgs sector of the NMSSM if the masses of the left-handed and the right-handed scalar-top quarks are not degenerate. Further, the phenomenology of the $K$-${\bar K}$ mixing within the context of our model is studied. The lower bound on CP violating phase in the $K$-${\bar K}$ mixing is found to increase if either $\tan\beta$ decreases or $A_t$ increases.