Probing lepton flavour violation via neutrinoless t?3µ decays with the ATLAS detector

This article presents the sensitivity of the ATLAS experiment to the lepton-flavour-violating decays of t?3µ. A method utilising the production of t leptons via W?t? decays is used. This method is applied to the sample of 20.3 fb -¹ of pp collision data at a centre-of-mass energy of 8 TeV collected by the ATLAS experiment at the LHC in 2012. No event is observed passing the selection criteria, and the observed (expected) upper limit on the t lepton branching fraction into three muons, Br(t?3µ) is 3.76×10-7 (3.94×10 -7) at 90 % confidence level.