Light (and darkness) from a light hidden Higgs
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Beyond Standard ModelExtended Supersymmetry
Vega, R., Vega-Morales, R. & Xie, K. J. High Energ. Phys. (2018) 2018: 137. [https://doi.org/10.1007/JHEP06(2018)137]
SponsorshipWe thank Andrew Akeroyd, Filippo Sala, Jose Santiago, Daniel Stolarski, and Lorenzo Ubaldi for useful comments and discussions. The work of R.V.M. is supported by MINECO, FPA 2016-78220-C3-1-P, FPA 2013-47836-C3-2/3-P (including ERDF), and the Juan de la Cierva program, as well as by Junta de Andalucia Project FQM-101. The work of R.V. is partially supported by the Sam Taylor fellowship. K.X. is supported by U. S. Department of Energy under Grant No. DE-SC0010129. K.X. also thanks Fermilab for their hospitality and partial support during this work.
We examine light diphoton signals from extended Higgs sectors possessing (approximate) fermiophobia with Standard Model (SM) fermions as well as custodial symmetry. This class of Higgs sectors can be realized in various beyond the SM scenarios and is able to evade many experimental limits, even at light masses, which are otherwise strongly constraining. Below the WW threshold, the most robust probes of the neutral component are di and multi-photon searches. Utilizing the dominant Drell-Yan Higgs pair production mechanism and combining it with updated LHC diphoton data, we derive robust upper bounds on the allowed branching ratio for masses between 45 − 160 GeV. Furthermore, masses ≲ 110 GeV are ruled out if the coupling to photons is dominated by W boson loops. We then examine two simple ways to evade these bounds via cancellations between different loop contributions or by introducing decays into an invisible sector. This also opens up the possibility of future LHC diphoton signals from a light hidden Higgs sector. As explicit realizations, we consider the Georgi-Machacek (GM) and Supersymmetric GM (SGM) models which contain custodial (degenerate) Higgs bosons with suppressed couplings to SM fermions and, in the SGM model, a (neutralino) LSP. We also breifly examine the recent ∼ 3σ CMS diphoton excess at ∼ 95 GeV.