Search for a light-charged Higgs in a two-Higgs-doublet type II seesaw model at the LHC

A charged Higgs in the type II two-Higgs-doublet model (THDM) has been bounded to be above a few hundred GeV by the radiative B decays. A Higgs triplet extension of the THDM not only provides an origin of neutrino masses and a completely new doubly-charged Higgs decay pattern, but it also achieves a light-charged Higgs with a mass of O(100)GeV through the new scalar couplings in the scalar potential. It was found that these light-charged Higgs decays depend on its mass mH±, tan⁡β, and mixing effect sin⁡θ±: at tan⁡β=1, if mH±>mW+mZ, b¯bW±, W±Z, and τν are the main decay modes; however, if mH±mH±+mb, we found that the ATLAS and CMS recent upper bounds on the product of BR(t→H+b)BR(H+→τ+ν) can be directly applied and will give a strict constraint on the correlation of mH± and sin⁡θ±. If the upper bound of BR(t→H+b)BR(H+→τ+ν) is satisfied (escaped) for mt>(<)mH±+mb, it was found that the significance of discovering the charged Higgs through H±→W±Z is much lower than that through H±→b¯bW±. With a luminosity of 100fb−1 at s=13TeV and including the experimental bounds, the significance of the H±→b¯bW± signal can reach around 6.2(2.4)σ for mH±<(>)mW+mZ.