Explanation of the excesses in associated di-photon production at 152 GeV in 2HDM

Abstract

Abstract Statistically significant excesses exist at around 152 GeV in associated di-photon production (γγ + X) in the sidebands of SM Higgs analyses of ATLAS (using the full run-2 dataset). They are most pronounced in the single-τ, missing-transverse-energy, four-jet and ⩾ 1ℓ+ ⩾ 1b-jet channels (≈ 3σ) and can be explained by the Drell-Yan production of new Higgs bosons, i.e. pp → W *→ H ± H 0. We first examine the excesses in a simplified model approach, considering that H ± decays to τν, WZ or tb. Both the τν and tb decay modes individually lead to a significance of ⪅ 4σ while for WZ one can obtain at most 3.5σ. This is because the decays of WZ lead to multiple leptons contributing to the two-lepton channel which does not show an excess at 152 GeV. Next, we consider two-Higgs-doublet models where the charged Higgs does not decay to WZ at tree-level, finding a significance of ⪆ 4σ for a branching ratio of the new neutral Higgs to photons of ≈2%. Even though this branching fraction is quite sizable, it can be obtained in composite models or via the Lagrangian term $${\lambda }_{6}{H}_{1}^{†}{H}_{1}{H}_{2}^{†}{H}_{1}$$ + h.c. breaking the commonly imposed Z 2 symmetry.

Keywords

• Multi-Higgs Models
• Specific BSM Phenomenology