Charged Higgs Search via $AW^\pm/HW^\pm$ Channel

Models of electroweak symmetry breaking with extended Higgs sectors are theoretically well motivated. In this study, we focus on models with a low energy spectrum containing a pair of charged scalars $H^\pm$, as well as a light scalar H and/or a pseudoscalar A. We study the $H^\pm tb$ associated production with $H^\pm \to AW/HW$, which could reach sizable branching fractions in certain parameter regions. With detailed collider analysis, we obtain the exclusion bounds as well as discovery reach at the 14 TeV LHC for the process $pp \to H^\pm tb \to AW^\pm tb/HW^\pm tb \to \tau\tau bbWW, bbbbWW$. We find that for a daughter particle mass of 70 GeV, the 95% C.L. exclusion reach in $\sigma$xBR varies from about 60 fb to 25 fb, for $m_{H^\pm}$ ranging from 150 GeV to 500 GeV with 300 fb$^{-1}$ integrated luminosity in the $\tau\tau$ mode. We further interpret these bounds in the context of Type II Two Higgs Doublet Model. The exclusion region in the $m_{H^\pm}-\tan\beta$ plane can be extended to $m_{H^\pm}=$ 600 GeV, while discovery is possible for $m_{H^\pm}\lesssim$ 400 GeV with 300 fb$^{-1}$ integrated luminosity. The exotic decay mode $H^\pm \to AW^\pm/HW^\pm$ offers a complementary channel to the conventional mode $H^\pm \to \tau\nu$ for charged Higgs searches.