Light signals from a lighter Higgs

Abstract

With the Higgs search program already quite mature, there is the exciting possibility of discovering a new particle with rates near that of the SM Higgs. We consider models with a signal in γγ below the SM Higgs mass. We discuss singlet models with additional vectorlike matter, but argue that a Type-I two Higgs doublet model can more easily provide detectable rates. In such scenarios, in regions of moderate-to-strong fermiophobia, the enhanced γγ branching ratio allows signals from V H+VBF production to yield σ × BRγγ comparable to total SM rates and would thus be detectable. Light H production can be dominated via rare top decays t → bH+ → bW∗H, which provides an even more efficient means of production. We also consider this in the context of various Higgs anomalies, specifically the recent 2.9 σ (local) CMS excess at 95 GeV, the LEP Higgs excess near the same mass, and excesses in tt¯ h searches at Tevatron and LHC. We find regions of parameter space that can meet all simultaneously. An implication of the Type-I scenario is that any γγ excess should be associated with additional elements that could reduce background, including b-jets, forward jets or signs of vector boson production.