Search for charged Higgs bosons through the violation of lepton universality in ttbar events using pp collision data at √s = 7 TeV with the ATLAS experiment

ATLAS COLLABORATION, G. AAD, F. MONTICELLI, ET AL

JOURNAL OF HIGH ENERGY PHYSICS

SPRINGER

Lugar: Berlin; Año: 2013 vol. 2013 p. 1 - 46

1126-6708

In several extensions of the Standard Model, the top quark can decay into abottom quark and a light charged Higgs boson H + , t → bH + , in addition to the StandardModel decay t → bW . Since W bosons decay to the three lepton generations equally, whileH + may predominantly decay into τ ν, charged Higgs bosons can be searched for using theviolation of lepton universality in top quark decays. The analysis in this paper is based on√4.6 fb−1 of proton-proton collision data at s = 7 TeV collected by the ATLAS experimentat the Large Hadron Collider. Signatures containing leptons (e or μ) and/or a hadronicallydecaying τ (τhad ) are used. Event yield ratios between e+τhad and e+μ, as well as betweenμ + τhad and μ + e, final states are measured in the data and compared to predictions fromsimulations. This ratio-based method reduces the impact of systematic uncertainties inthe analysis. No significant deviation from the Standard Model predictions is observed.With the assumption that the branching fraction B(H + → τ ν) is 100%, upper limits inthe range 3.2%–4.4% can be placed on the branching fraction B(t → bH + ) for chargedHiggs boson masses mH + in the range 90–140 GeV. After combination with results from a ̄search for charged Higgs bosons in tt decays using the τhad +jets final state, upper limitson B(t → bH + ) can be set in the range 0.8%–3.4%, for mH + in the range 90–160 GeV.