Evidence for the 125 GeV Higgs Boson Decaying into Taus at the CMS Experiment

A search for a standard model (SM) Higgs boson decaying into a pair of τ leptons is performed using events recorded by the CMS experiment at the LHC in 2011 and 2012. The dataset corresponds to an integrated luminosity of 4.9fb−1 at a centre-of-mass energy of 7 TeV and 19.7fb−1 at 8 TeV. Each τ lepton decays hadronically or leptonically to an electron or a muon, leading to six different final states for the τ-lepton pair, all considered in this analysis. An excess of events is observed over the expected background contributions, with a local significance larger than 3 standard deviations for mH values between 115 and 130 TeV. The best fit of the observed H→ττ signal cross section times branching fraction for mH=125GeV is 0.78 ± 0.27 times the standard model expectation. These observations constitute evidence for the 125 GeV Higgs boson decaying into a pair of τ leptons.