Study Of Mass-degenerate Higgs Bosons Near 125 GeV In The NMSSM

The discovery of Higgs boson by ATLAS and CMS collaborations in 2012 stands for the beginning of a new epoach for high-energy physics.So far,the properties of the Higgs boson,such as the coupling with other Standard Model(SM)particles,have been precisely measured.And the measured properities are in accord with the prediction of SM.However,the current central values of some decay channels,h→γγ,which depart from the expectation of SM.Therefore,there have been many attempts to explain the excesses of the signals.Moreover,the existence of only one Higgs boson is not sufficient to fit the datas.A varity of models solve the issue by introducing a unobserved or degenerate state that mixes with the observed Higgs boson mass eigenstates.One of the most appealing model could obtain two quasi-degenerate Higgs boson is the Next-to-Minimal Supwesymmetric Standard Model(NMSSM).It provides an elegant solution to the μ problem of the minimal supersymmetric extension of the standard model(MSSM).In addition,some experimental constraints on the NMSSM can be weaker due to the mixing between the singlet superfield with the doublet Higgs fields.As a result,some unique phenomenological properties of the Higgs boson may appear in the NMSSM.The most attractive properties of the NMSSM is the possibility that the two lightest CP-even Higgs bosons can both lie in the 122-128 GeV mass range.In this paper,we aim to reproduce the observed Higgs signal by the superposition of these two Higgs states.We perform a comprehensive scan over the parameters in the NMSSM considering the current experimental constraints,especially the constraints from dark matter direct detection.The surviving samples are featured with relatively small λ and large tan β.Most importantly,the samples with large deviation of ratios have a good χ2 to the experimental data and large mixing between doublet field and singlet field.Based on our results of calculation,it provides a possibility that two mass-degenerate Higgs bosons can reproduce the signal strengths observed in the experiments.The decay of Higgs bosons to bb is one of the most improtant channels,which can help us distinguish between single and two mass-degenerate signal.