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

TL;DR

This paper investigates whether observed excesses around 95 GeV in multiple decay channels can be explained within the Two Higgs Doublet type II Seesaw Model, showing a consistent parameter space that accounts for all excesses simultaneously.

Contribution

It demonstrates that the 2HDMcT model can simultaneously explain the 95 GeV excesses in diphoton, di-tau, and b-bbar channels, especially with nearly degenerate CP-odd and CP-even Higgs bosons.

Findings

A light CP-even Higgs around 95 GeV can explain the excesses in gamma gamma and b-bbar channels.

The three excesses can be simultaneously accommodated with a 0.64 sigma confidence level.

Nearly degenerate CP-odd Higgs enhances the combined explanation of the excesses.

Abstract

In the search for a light Higgs boson, the ATLAS and CMS experiments have observed excesses in both the diphoton ($\gamma\gamma$) and di-tau-pair ($\tau^+\tau^-$) 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 $\gamma\gamma$ and $b\bar{b}$ channels, provided a Type I Yukawa texture is employed. More interestingly, our analysis shows that the three excesses in $\gamma\gamma$, $b\bar{b}$ and $\tau^+\tau^-$ channels can well be accommodated simultaneously, reaching a $0.64 \sigma$ C.L. if the CP-odd Higgs boson $A_1$ is nearly mass degenerate and superposed to the light CP-even Higgs $h_1$.