This article presents the sensitivity of theATLAS experiment to the lepton-flavour-violating decays of τ → 3μ. A method utilising the production of τ leptons via W → τν 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 τ lepton branching fraction into three muons,Br(τ → 3μ),is 3.76 × 10−7 (3.94 × 10−7) at 90 % confidence level.

Aad, G., Abbott, B., Abdallah, J., Abdinov, O., Aben, R., Abolins, M., et al. (2016). Probing lepton flavour violation via neutrinoless τ → 3μ decays with the ATLAS detector. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 76(5), 232 [10.1140/epjc/s10052-016-4041-9].

Probing lepton flavour violation via neutrinoless τ → 3μ decays with the ATLAS detector

F. Ceradini;B. Di Micco;R. Di Nardo;D. Orestano;F. Petrucci;D. Puddu;G. Salamanna;