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

Abstract

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.