Explaining 650 GeV and 95 GeV Anomalies in the 2-Higgs Doublet Model Type-I

Abstract

We propose an interpretation of a rather significant 650 GeV excess emerged at the Large Hadron Collider (LHC) from CMS Collaboration data in the $γγb\bar b$ final state, accompanied by further clusters at 125(90-100) GeV in the $γγ(b\bar b)$ system, within the 2-Higgs Doublet Model Type-I (2HDM-I) in presence of a softly broken $\mathcal{Z}_{2}$ symmetry. The underlying process that we probe is $gg$-initiated production of a CP-odd (or pseudoscalar) Higgs boson $A$, with mass around 650 GeV, decaying into the Standard Model (SM)-like Higgs state $H$ (decaying into $γγ$) and a $Z$ boson (decaying into $b\bar b$). We configure this theoretical framework so as to also have in the spectrum a light CP-even (or scalar) Higgs state $h$ with mass around 95 GeV, which is included for the purpose of simultaneously explaining additional data anomalies seen in the $b\bar b$, $γγ$ and $τ^+τ^-$ final states while searching for light Higgs states at the Large Electron-Positron (LEP) collider (the first one) and LHC (the last two). By accounting for both experimental and theoretical constraints, our results show that the 2HDM-I can explain all aforementioned anomalies at a significance level of $2.5 σ$.