Identifying a light charged Higgs boson at the LHC Run II

Abstract

We analyse the phenomenological implications of a light Higgs boson, h, within the CP-conserving 2-Higgs Doublet Model (2HDM) Type-I, for the detection prospects of the charged H± state at Run II of the Large Hadron Collider (LHC), assuming s=13 TeV as energy and O(100 fb−1) as luminosity. When sufficiently light, this h state can open up the bosonic decay channel H±→W±(⁎)h, which may have a branching ratio significantly exceeding those of the H±→τν and H±→cs channels. We perform a broad scan of the 2HDM Type-I parameter space, assuming the heavier of the two CP-even Higgs bosons, H, to be the observed SM-like state with a mass near 125 GeV. Through these scans we highlight regions in which mH±<mt+mb that are still consistent with the most recent limits from experimental searches. We find in these regions that, when the H±→W±(⁎)h decay mode is the dominant one, the h can be highly fermiophobic, with a considerably large decay rate in the γγ channel. This can result in the total cross section of the σ(pp→H±h→W±(⁎)+4γ) process reaching up to O(100 fb). We therefore investigate the possibility of observing this spectacular signal at the LHC Run II.