Observation of the Higgs boson decay to a pair of τ leptons

A measurement of the coupling strength of the Higgs boson to τ leptons is performed using events recorded in proton-proton collisions by the CMS experiment at the LHC in 2016 at a center-of-mass energy of 13 TeV. The data set corresponds to an integrated luminosity of 35.9 fb − 1 . The H → ττ signal is established with a significance of 4.9 standard deviations, to be compared to an expected significance of 4.7 standard deviations. The best fit of the product of the observed H → ττ signal production cross section and branching fraction is 1.09 + 0.27 − 0.26 times the standard model expectation. The combination with the corresponding measurement performed with data collected by the CMS experiment at center-of-mass energies of 7 and 8 TeV leads to an observed significance of 5.9 standard deviations, equal to the expected significance. This is the first observation of Higgs boson decays to τ leptons by a single experiment. top quark Higgs boson decays a pair of bosons. band accounts for all sources of background uncertainty, systematic as well as statistical, after the global fit. The signal is both stacked filled his-togram and an open overlaid is normalized to its best fit signal strength. The mass distributions for a constant range of the second dimension of the signal distributions are weighted according to S / ( S + B ) , where S and B are computed, respectively, as the signal or background contribution in the mass distribution excluding the first and last bins. The “Others” background contribution includes events from diboson, tt, and single top quark production, as well as Higgs boson decay to a pair of W bosons and Z bosons decaying to a pair of light leptons. The background uncertainty band accounts for all sources of background uncertainty, systematic as well as statistical, after the global fit. The inset shows the corresponding difference between the observed data and expected background distributions, together with the signal expectation. The signal yield is not affected by the reweighting.