Abstract

A measurement of the Standard Model Higgs boson produced in association with a W or Z boson and decaying into a pair of tau-leptons is presented. This search is based on proton-proton collision data collected at root s = 13 TeV by the ATLAS experiment at the LHC corresponding to an integrated luminosity of 140 fb-1. For the Higgs boson candidate, only final states with at least one tau-lepton decaying hadronically (tau -> hadrons + nu(tau)) are considered. For the vector bosons, only leptonic decay channels are considered: Z -> ll and W -> l nu(l), with l = e, mu. An excess of events over the expected background is found with an observed (expected) significance of 4.2 (3.6) standard deviations, providing evidence of the Higgs boson produced in association with a vector boson and decaying into a pair of tau-leptons. The ratio of the measured cross-section to the Standard Model prediction is mu(tau tau)(VH) = 1.28(-0.29) (+0.30) (stat.) (+0.25)(-0.21) (syst.). This result represents the most accurate measurement of the VH (tau tau) process achieved to date.