Charged Higgs search in top quark decays with the ATLAS detector

The observation of a charged Higgs boson would be a clear sign of new physics beyond the Standard Model (SM). In the Minimal Supersymmetric Standard Model (MSSM), the charged Higgs could be copiously produced in the decays of the top quark, if kinematically allowed. In this note, the charged Higgs discovery potential of the ATLAS detector at the LHC is presented through the study of a new channel: $pp\rightarrow t\bar{t} \rightarrow H^{\pm}b W^{\mp}\bar{b}$ with $H^{\pm}\rightarrow \tau \nu$ and $W^{\mp} \rightarrow q\bar{q}\prime$ (hadronic channel). This channel leads to an improvement in the expected sensitivity of the ATLAS detector to the discovery of the MSSM Higgs bosons. In particular, for charged Higgs masses below the top quark mass and in the intermediate $\tan\beta$ region ($\tan\beta=5-10$), signal significances upwards of 5$\sigma$ can be reached with an integrated luminosity of 10 fb$^{-1}$. Furthermore, the mass of the charged Higgs boson can be determined from the transverse mass distribution with a precision of about 4\%.