Search for a charged Higgs boson in pp collisions at $ \sqrt{s}=8 $ TeV

A search for a charged Higgs boson is performed with a data sample corresponding to an integrated luminosity of 19.7 ± 0.5 fb$^{−1}$ collected with the CMS detector in proton-proton collisions at $\sqrt{s}=8$ ,TeV. The charged Higgs boson is searched for in top quark decays for m$_{H}$± < m$_{t}$ − m$_{b}$, and in the direct production pp → t(b)H$^{±}$ for m$_{H}$± > m$_{t}$ − m$_{b}$. The H$^{±}$ → τ$^{±}$ ν$_{τ}$ and H$^{±}$ → tb decay modes in the final states τ$_{h}$+jets, μτ$_{h}$, ℓ+jets, and ℓℓ’ (ℓ =e, μ) are considered in the search. No signal is observed and 95% confidence level upper limits are set on the charged Higgs boson production. A model-independent upper limit on the product branching fraction $\mathrm{\mathcal{B}}\left(\mathrm{t}\to {\mathrm{H}}^{\pm}\mathrm{b}\right)\mathrm{\mathcal{B}}\left({\mathrm{H}}^{\pm}\to {\tau}^{\pm }{\nu}_{\tau}\right)=1.2-0.15\%$ is obtained in the mass range m$_{H}$± = 80–160 GeV, while the upper limit on the cross section times branching fraction $\sigma \left(\mathrm{pp}\to \mathrm{t}\left(\mathrm{b}\right){\mathrm{H}}^{\pm}\right)\mathrm{\mathcal{B}}\left({\mathrm{H}}^{\pm}\to\ {\tau}^{\pm }{\nu}_{\tau}\right)=0.38-0.025$ pb is set in the mass range m$_{H}$+ = 180–600 GeV. Here, σ(pp → t(b)H$^{±}$) stands for the cross section sum $\sigma \left(\mathrm{pp}\to \overline{\mathrm{t}}\left(\mathrm{b}\right){\mathrm{H}}^{+}\right)+\sigma \left(\mathrm{pp}\to \mathrm{t}\left(\overline{\mathrm{b}}\right){\mathrm{H}}^{-}\right)$ . Assuming $\mathrm{\mathcal{B}}\left({\mathrm{H}}^{\pm}\to \mathrm{t}\mathrm{b}\right)=1$ , an upper limit on σ(pp → t(b)H$^{±}$) of 2.0–0.13 pb is set for m$_{H}$± = 180–600 GeV. The combination of all considered decay modes and final states is used to set exclusion limits in the m$_{H}$±−tan β parameter space in different MSSM benchmark scenarios.