Probing the CP-violating light neutral Higgs in the charged Higgs decay at the LHC

Abstract

The CP-violating MSSM allows existence of a light neutral Higgs boson ($M_{H_1}\text{lapp}50$ GeV) in the CPX scenario in the low $\tan \beta (\text{lapp}5)$ region, which could have escaped the LEP searches due to a strongly suppressed $H_{1}ZZ$ coupling. This parameter space corresponds to a relatively light $H^{\pm }$ ($M_{H^{\pm }}<M_t$), which is predicted to decay dominantly into the $W{H}_1$ channel. Thus one expects to see a striking $t\bar{t}$ signal at the LHC, where one of the top quarks decays into the $bb\bar{b}W$ channel, via $t\to b{H}^{\pm },H^{\pm }\to W{H}_1$ and $H_1\to b\bar{b}$. The characteristic correlation between the $b\bar{b}$, $b\bar{b}W$ and $bb\bar{b}W$ invariant mass peaks is expected to make this signal practically free of the SM background. Our parton level Monte Carlo simulation yields upto 5000 events, for $\mathcal{L}=30$ fb${}^{-1}$, over the parameter space of interest, after taking into account the b-tagging efficiency for three or more b-tagged jets.

Comments: 13 pages, 4 figures, LaTeX. Version to appear in Phys. Lett. B. Extended discussions of the QCD and combinatorial backgrounds