Detecting Heavy Charged Higgs Bosons at the LHC with Four b-Quark Tags

We investigate the signature of a heavy charged Higgs boson of the Minimal Supersymmetric Standard Model in the lepton plus multi-jet channel at the Large Hadron Collider with four $b$-tags. The signal is the gluon-gluon fusion process $gg\to t\bar b H^-$, followed by the $H^-\to \bar t b$ decay, while the main background is from $gg\to t\bar t b\bar b$. We find that the two can be separated effectively by kinematic cuts and mass reconstruction, but the signal size is not very large in the end. Nonetheless, with a good $b$-tagging efficiency, $\epsilon_b\sim50%$, this channel can provide a viable signature over a limited but interesting range of the parameter space.