Search for the Standard Model Higgs boson in $H \to \tau^+ \tau^-$ decays in proton-proton collisions with the ATLAS detector

A search for the Standard Model (SM) Higgs boson decaying into a pair of tau leptons is reported. The analysis, exploiting each of the lepton-lepton, lepton-hadron and hadron-hadron di-tau final states, is based on data samples of proton-proton (pp) collisions collected by the ATLAS experiment at the Large Hadron Collider (LHC) and corresponding to integrated luminosities of 4.6 fb^-1 and 13:0 fb^-1 at center-of-mass energies of s**(1/2) = 7 TeV and 8 TeV, respectively. The observed (expected) upper limit at 95%CL on the cross-section times the branching ratio for SM H -> tau^+tau^- Cis found to be 1.9(1.2) times the SM prediction for a Higgs boson with mass m_H = 125 GeV. For this mass, the observed (expected) deviation from the background-only hypothesis corresponds to a local significance of 1.1 (1.7) standard deviations.