A measurement of the high-mass τ -τ production cross-section at SQUARE ROOTs = 13 TeV with the ATLAS detector and constraints on new particles and couplings

Abstract

The production cross-section of high-mass τ -lepton pairs is measured as a functionof the dilepton visible invariant mass, using 140 fb-1 of SQUARE ROOTs = 13TeV proton-proton collisiondata recorded with the ATLAS detector at the Large Hadron Collider. The measurementagrees with the predictions of the Standard Model. A fit to the invariant mass distributionis performed as a function of b-jet multiplicity, to constrain the non-resonant production ofnew particles described by an effective field theory or in models containing leptoquarks orZ' bosons that couple preferentially to third-generation fermions. The constraints on newparticles improve on previous results, and the constraints on effective operators include those affecting the anomalous magnetic moment of the τ -lepton.