Search for H+- gt tau+nu with l+tau(- gt had) and ll final states in CMS

A search for a light charged Higgs boson is presented, conducted using $t\bar{t}$ events with $t\rightarrow bH^{\pm}$ and subsequent $H^{\pm}\rightarrow\tau^{\pm}\nu_{\tau}$ decay modes. The analysed data corresponded to an integrated luminosity of $\sim2~fb^{-1}$ recorded in proton-proton collisions at $\sqrt{s}=7~TeV$ by the CMS experiment at the LHC. The final states presented require the presence of a $\tau$ lepton from $H^{\pm}$ decays, an isolated lepton ($e$ or $\mu$) from $W^{\pm}$ decay and jets from the top quark decays. No excess of events was observed with respect to the expected SM background. Model-independent upper limits on the $t\rightarrow bH^{\pm}$ branching fraction were established in the range $2--4\pct$ for charged Higgs boson masses between $80$ and $160~GeV$, under the assumption $\mathrm{B}(H^{\pm}\rightarrow\tau^{\pm}\nu_{\tau}=1$. The limits were transformed in model-dependend upper limits on $tan(\beta)$ as a function of the charged Higgs mass, assuming the MSSM maximal mixing scenario.