Higgs phenomenology in the Peccei-Quinn invariant NMSSM

Abstract

We study the Higgs phenomenology in the Peccei-Quinn invariant NMSSM (PQ-NMSSM) where the low energy mass parameters of the singlet superfield are induced by a spontaneous breakdown of the Peccei-Quinn symmetry. In the generic NMSSM, scalar mixing among CP-even Higgs bosons is constrained by the observed properties of the SM-like Higgs boson, as well as by the LEP bound on the chargino mass and the perturbativity bound on the singlet Yukawa coupling. In the minimal PQ-NMSSM, scalar mixing is further constrained due to the presence of a light singlino-like neutralino. It is noticed that the $2\sigma$ excess of the LEP $Zb\bar{b}$ events at $m_{b\bar{b}}\simeq$ 98 GeV can be explained by a singlet-like 98 GeV Higgs boson in the minimal PQ-NMSSM with low $\tan \beta$, stops around or below 1 TeV, and light doublet-higgsinos around the weak scale.

Comments: 31 pages, 4 figures; v2: references added, light stop effects discussed, bound on the Higgs invisible decay rate corrected