Unified Interpretation of 95 GeV Excesses in the Two Higgs Doublet type II Seesaw Model

Abstract

In the search for a light Higgs boson, the ATLAS and CMS experiments have observed excesses in both the diphoton ($γγ$) and di-tau-pair ($τ^+τ^-$) decay channels at about $95$ GeV. The LEP collaboration has also previously reported an excess in the $b\bar{b}$ channel at a comparable Higgs mass. In this paper, we explore whether these excesses can be accommodated within the framework of the Two Higgs Doublet type II Seesaw Model (2HDMcT). By implementing various theoretical constraints and experimental limits on the parameter space, we first demonstrate that a light CP-even Higgs boson, $h_1$, with a mass around 95 GeV can simultaneously account for the excesses observed in the $γγ$ and $b\bar{b}$ channels, provided a Type I Yukawa texture is employed. More interestingly, our analysis shows that the three excesses in $γγ$, $b\bar{b}$ and $τ^+τ^-$ channels can well be accommodated simultaneously, reaching a $0.64 σ$ C.L. if the CP-odd Higgs boson $A_1$ is nearly mass degenerate and superposed to the light CP-even Higgs $h_1$.