Probing the light neutral Higgs boson scenario of the CP-violating MSSM Higgs sector at the LHC

In the CP-violating Minimal Supersymmetric Standard Model (MSSM), for certain values of the CP-violating phases associated to the universal trilinear couplings $(A_t, A_b)$ and the gluino mass $(M_{\tilde g})$, e.g., $\Phi_{\rm{CP}} = 60^\circ$ or $90^\circ$, for $M_{H^+} \lsim 140 $ GeV and $\tan \beta \sim 2-5 $, the lightest Higgs boson mass ($M_{H_1}$) is $\lsim 50 $ GeV. This mass interval is still allowed from standard LEP Higgs searches because of a strongly suppressed $H_1ZZ$ coupling. However, in the same region of parameter space in which these two conditions occur, the $H_1 H^\mp W^\pm $ coupling is enhanced because the two mentioned sets of couplings satisfy a sum rule. In this paper we probe such a light Higgs scenario at the Large Hadron Collider (LHC) by studying $H^\pm H_1$ associate production, leading to a $4b + \ell^\pm + \mET $ signal. We show that the latter is readily accessible at the CERN hadron collider, upon the application of suitable selection cuts against the Standard Model (SM) backgrounds. Our parton level Monte Carlo (MC) analysis yields $\sim 15-45 $ signal events, completely free of SM background, for ${\cal L} = 10-30 {\rm fb}^{-1}$ of accumulated luminosity, after taking into account the overall efficiency for tagging four $b$-jets.