ATLAS discovery potential for a heavy charged Higgs boson

The sensitivity of the ATLAS detector to the discovery of a heavy charged Higgs boson is presented. Assuming a heavy SUSY spectrum, the most promising channels above the top quark mass are $H^pmto tb$ and $H^pmtotau^pm u_tau$ which provide coverage in the low and high $tanbeta$ regions up to $sim 600$ GeV. The achievable precisions on the charged Higgs mass and $tanbeta$ determination are also discussed. The $H^pmto W^pm h^0$ channel, though restricted to a small MSSM parameter space, shows a viable signal in NMSSM where the parameter space is less constrained. The observation of the channel $H^-totau^-_L u_tau + c.c.$ may constitute a distinctive evidence for models with singlet neutrinos in large extra dimensions.