Search for charged Higgs bosons in the $\tau$+jets final state with pp collision data recorded at $\sqrt s=8$ TeV with the ATLAS experiment

The experimental observation of charged Higgs bosons, $H^{\pm}$, which are predicted by many models with an extended Higgs sector, would indicate physics beyond the Standard Model. This note presents the results of a search for charged Higgs bosons in 19.5 fb$^{-1}$ of proton-proton collision data recorded at $\sqrt{s}=8$ TeV with the ATLAS experiment, using the $\tau$ + jets channel with a hadronically decaying $\tau$ lepton in the final state. For light charged Higgs bosons ( $m_{H^{+}} < m_{\text{top}}$), the $t\bar{t} \rightarrow H^+bWb$ production mode is dominant, while for heavy charged Higgs bosons, associated production of $tH^+$ is dominant. No evidence for a charged Higgs boson is found. For the mass range 90 GeV $ < m_{H^+} <160 $ GeV, 95$\%$ confidence level upper limits on $B(t \rightarrow H^+ b)$ are set in the range $0.24-2.1 \%$, and for the mass range 180 GeV $ < m_{H^+}<600$ GeV, 95$\%$ confidence level upper limits are set on the production cross section of a charged Higgs boson in the range $0.017-0.9$ pb, both with the assumption that $B(H^+ \to \tau\nu)=1$.