Analysis of $W^{\pm }+4\gamma$ in the 2HDM Type-I at the LHC

Abstract

We analyse a light charged Higgs boson in the 2-Higgs Doublet Model (2HDM) Type-I, when its mass satisfies the condition $M_{H^{\pm }}<M_t+M_b$ and the parameter space is consistent with theoretical requirements of self-consistency as well as the latest experimental constraints from Large Hadron Collider (LHC) and other data. Over such a parameter space, wherein the Standard Model (SM)-like state discovered at the LHC in 2012 is the heaviest CP-even state of the 2HDM, it is found that the decay modes of the charged Higgs boson are dominated by $H^{\pm }\to W^{\pm \ast }h$. Furthermore, the light neutral Higgs boson $h$ dominantly decays into two photons. Under these conditions, we find that the production and decay process $pp\to H^{\pm }h\to {W^{\pm }}^{(\ast )}hh\to l{\nu }_l+4\gamma$ ($l=e,\mu$) is essentially background free. However, since the $W^{\pm (\ast )}$ could be largely off-shell and the $h$ state is very light, so that both the lepton coming from the former and the photons coming from the latter could be rather soft, we perform here a full Monte Carlo (MC) analysis at the detector level demonstrating that such a $W^{\pm }+4\gamma$ signal is very promising, as it would be yielding significant excesses at the LHC with an integrated luminosity of $L=$ 300 $f{b}^{-1}$ at both $\sqrt{s}=13$ and $14\text{TeV}$.

Comments: 21 pages, 18 figures