In several extensions of the Standard Model, the top quark ca n decay into a bottom quark and a light charged Higgs boson H + , t → bH + , in addition to the Standard Model decay t → bW . Since W bosons decay to the three lepton generations equally, while H + may predominantly decay into τν , charged Higgs bosons can be searched for using the violation of lepton universality in top quark decays. The an alysis in this paper is based on 4.6fb − 1 of proton-proton collision data at √ s = 7 TeV collected by the ATLAS experiment at the Large Hadron Collider. Signatures containing lepton s ( e or μ ) and/or a hadronically decaying τ ( τ had ) are used. Event yield ratios between e + τ had and e + μ , as well as between μ + τ had and μ + e , final states are measured in the data and compared to predict ions from simulations. This ratio-based method reduces the impact of systematic uncertainties in the analysis. No significant deviation from the Standard Mod el predictions is observed. With the assumption that the branching fraction B ( H + → τν ) is 100%, upper limits in the range 3.2%–4.4% can be placed on the branching fraction B ( t → bH + ) for charged Higgs boson masses m H + in the range 90–140GeV. After combination with results from a search for charged Higgs bosons in t ̄ t decays using the τ had +jets final state, upper limits on B ( t → bH + ) can be set in the range 0.8%–3.4%, for m H + in the range 90–160GeV.
Search for charged Higgs bosons through the violation of lepton universality in $ t\overline{t} $ events using pp collision data at $ \sqrt{s}=7 $ TeV with the ATLAS experiment
BELLAGAMBA, LORENZO;BERTIN, ANTONIO;BOSCHERINI, DAVIDE;BRUNI, ALESSIA;BRUNI, GRAZIANO;CAFORIO, DAVIDE;DE CASTRO, STEFANO;DI SIPIO, RICCARDO;FABBRI, LAURA;FRANCHINI, MATTEO;GIACOBBE, BENEDETTO;MASSA, IGNAZIO GIACOMO;MENGARELLI, ALBERTO;MONZANI, SIMONE;PICCININI, MAURIZIO;RINALDI, LORENZO;ROMANO, MARINO;SBARRA, CARLA;SBRIZZI, ANTONIO;SEMPRINI CESARI, NICOLA;SPIGHI, ROBERTO;VALENTINETTI, SARA;VILLA, MAURO;I. Vivarelli;ZOCCOLI, ANTONIO;
2013
Abstract
In several extensions of the Standard Model, the top quark ca n decay into a bottom quark and a light charged Higgs boson H + , t → bH + , in addition to the Standard Model decay t → bW . Since W bosons decay to the three lepton generations equally, while H + may predominantly decay into τν , charged Higgs bosons can be searched for using the violation of lepton universality in top quark decays. The an alysis in this paper is based on 4.6fb − 1 of proton-proton collision data at √ s = 7 TeV collected by the ATLAS experiment at the Large Hadron Collider. Signatures containing lepton s ( e or μ ) and/or a hadronically decaying τ ( τ had ) are used. Event yield ratios between e + τ had and e + μ , as well as between μ + τ had and μ + e , final states are measured in the data and compared to predict ions from simulations. This ratio-based method reduces the impact of systematic uncertainties in the analysis. No significant deviation from the Standard Mod el predictions is observed. With the assumption that the branching fraction B ( H + → τν ) is 100%, upper limits in the range 3.2%–4.4% can be placed on the branching fraction B ( t → bH + ) for charged Higgs boson masses m H + in the range 90–140GeV. After combination with results from a search for charged Higgs bosons in t ̄ t decays using the τ had +jets final state, upper limits on B ( t → bH + ) can be set in the range 0.8%–3.4%, for m H + in the range 90–160GeV.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.