Interplay of $95$ GeV Diphoton Excess and Dark Matter in Supersymmetric Triplet Model

The decay of the Higgs boson and the nature of dark matter remain fundamental challenges in particle physics. We investigate the $95$ GeV diphoton excess and dark matter within the framework of the triplet-extended Minimal Supersymmetric Standard Model (TMSSM). In this model, an additional Hypercharge $Y=0$, $SU(2)_L$ triplet superfield is introduced. Mixing between the triplet and doublet Higgs states enhances the diphoton signal strength of the $95$ GeV Higgs boson, resulting in $\mu_{\gamma\gamma}^{\text{CMS+ATLAS}} = 0.24_{-0.08}^{+0.09}$, which is consistent with experimental observations. This enhancement arises primarily from charged Higgs loop contributions. Additionally, the model accommodates viable dark matter candidates in the form of a bino-dominated neutralino. The relic density is reduced to the observed value through resonance-enhanced annihilation via the Higgs portal or co-annihilation with the triplino or higgsino. This reduction remains consistent with constraints from direct and indirect detection experiments. A comprehensive parameter scan demonstrates that the TMSSM can simultaneously explain the $95$ GeV diphoton excess, the observed $125$ GeV Higgs mass, and the dark matter relic density, establishing a compelling and theoretically consistent framework.