Mass-degenerate Higgs bosons near 125 GeV in the NMSSM under current experimental constraints

The observed Higgs signal at the Large Hadron Collider (LHC) may be derived from the two mass-degenerate resonances. We investigate this scenario in the Next-to-Minimal Supersymmetric Standard Model (NMSSM) in which both the two lightest CP-even Higgs bosons have masses around 125 GeV. 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 mu and large tan beta. The samples with large deviation of double ratios have large mixing between doublet field and singlet field.