A search for lepton-flavour violating τ→ 3μ decays with the ATLAS detector · arXivDesk
2603.18099Mar 18, 202637 pages in total, author list starting page 20, 4 figures, 3 tables, published to Phys. Lett. B 880 (2026) 140748. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/BPHY-2018-05
A search for lepton-flavour violating τ→3μ decays with the ATLAS detector
A search for charged lepton flavour violation in τ→3μ decays is performed in pp collisions at a centre-of-mass energy of 13 TeV using ATLAS data collected between 2016 and 2018, corresponding to an integrated luminosity of 137 fb−1. The search is optimised for the electroweak W→τν
Nearby in the stack
production channel, due to its higher trigger efficiency, but also considers potential signal events from heavy-flavour production. Data are collected using two-muon and three-muon triggers and a multivariate analysis is used to separate the signal from the background. An unbinned likelihood fit is then performed to the resulting three-muon invariant mass spectrum and the data are found to be compatible with the background-only hypothesis. The observed (expected) limit on the branching ratio