Abstract
Abstract A search for the Standard Model Higgs boson decaying into a pair of τ leptons is reported. The analysis is based on a data sample of proton-proton collisions collected by the ATLAS experiment at the LHC and corresponding to an integrated luminosity of 4.7 fb−1. No significant excess over the expected background is observed in the Higgs boson mass range of 100–150 GeV. The observed (expected) upper limits on the cross section times the branching ratio for H → τ + τ − are found to be between 2.9 (3.4) and 11.7 (8.2) times the Standard Model prediction for this mass range.
Highlights
Next-to-next-to-leading-order (NNLO) Quantum Chromodynamics (QCD) corrections, soft-gluon resummations calculated in the next-to-next-toleading-log-approximation and next-to-leading-order (NLO) electroweak (EW) corrections are applied to the signal cross sections for the gg → H production process [13,14,15,16,17,18,19,20,21,22,23,24]
In a sample of selected Z/γ∗ → μμ data events, the muon tracks and associated calorimeter cells are replaced by τ leptons from a simulated Z/γ∗ → τ τ decay with the same kinematics, where the τ polarisation and spin correlations are modelled with the TAUOLA program and the τ -μ mass difference is taken into account as well
The dominant correlated systematic uncertainties are those on the measurement of the integrated luminosity and on the theoretical predictions of the signal production cross sections and decay branching ratios, as well as those related to detector response that impact the analyses through the reconstruction of electrons, muons, hadronic τ decays, jets, ETmiss and b-tagging
Summary
The ATLAS detector is a multipurpose apparatus with a forward-backward symmetric cylindrical geometry and nearly 4π coverage in solid angle [12]. Next-to-next-to-leading-order (NNLO) Quantum Chromodynamics (QCD) corrections, soft-gluon resummations calculated in the next-to-next-toleading-log-approximation and next-to-leading-order (NLO) electroweak (EW) corrections are applied to the signal cross sections for the gg → H production process [13,14,15,16,17,18,19,20,21,22,23,24]. The cross sections of the VBF process are calculated with full NLO QCD and electroweak corrections [25,26,27], and approximate NNLO QCD corrections [28]. ALPGEN [37], interfaced to HERWIG [38], with the MLM matching scheme [39] is used to model the production of single W and Z/γ∗ bosons decaying to charged leptons in association with jets.
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