Light Charged Higgs Bosons to AW/HW via Top Decay

Abstract

While current ATLAS and CMS measurements exclude a light charged Higgs ($m_{H^{\pm }}<160$ GeV) for most of the parameter region in the context of the MSSM scenarios, these bounds are significantly weakened in the Type II 2HDM once the exotic decay channel into a lighter neutral Higgs, $H^{\pm }\to AW/HW$, is open. In this study, we examine the possibility of a light charged Higgs produced in top decay via single top or top pair production, with the subsequent decay $H^{\pm }\to AW/HW$, which can reach a sizable branching fraction at low $\tan {\hat{I}}^2$ once it is kinematically permitted. With a detailed collider analysis, we obtain exclusion and discovery bounds for the 14 TeV LHC assuming the existence of a 70 GeV neutral scalar. Assuming $\mathrm{BR}(H^{\pm }\to AW/HW)=100\%$ and $\mathrm{BR}(A/H\to \ddot{I}„\ddot{I}„)=8.6\%$, the 95% exclusion limits on $\mathrm{BR}(t\to H^{+}b)$ are about 0.2% and 0.03% for single top and top pair production respectively, with an integrated luminosity of 300 ${\mathrm{fb}}^{-1}$. The discovery reaches are about 3 times higher. In the context of the Type II 2HDM, discovery is possible at both large $\tan {\hat{I}}^2>17$ for 155 GeV $<m_{H^{\pm }}<$ 165 GeV, and small $\tan {\hat{I}}^2<6$ over the entire mass range. Exclusion is possible in the entire $\tan {\hat{I}}^2$ versus $m_{H^{\pm }}$ plane except for charged Higgs masses close to the top threshold. The exotic decay channel $H^{\pm }\to AW/HW$ is therefore complementary to the conventional $H^{\pm }\to \ddot{I}„\hat{I}½$ channel.

21 pages. arXiv admin note: text overlap with arXiv:1408.4119