A measurement of the H→ττ signal strength 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 13TeV. The data set corresponds to an integrated luminosity of 35.9fb−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 1.09−0.26+0.27 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 8TeV 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.
Sirunyan, A. M., Tumasyan, A., Adam, W., Ambrogi, F., Asilar, E., Bergauer, T., … Woods, N. (2018). Observation of the Higgs boson decay to a pair of τ leptons with the CMS detector. Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 779, 283–316. https://doi.org/10.1016/j.physletb.2018.02.004