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A search for lepton-flavour violatingτ→ 3μdecays with the ATLAS detector
 

A search for lepton-flavour violatingτ→ 3μdecays with the ATLAS detector

Georges Aad, Erlend Aakvaag, Braden Keim Abbott, Sara Abdelhameed, Kira Abeling, Nils Julius Abicht, Haider Abidi, Mohammed Aboelela, Asmaa Aboulhorma, Halina Abramowicz, …
Phys.Lett.B, Vol.880, 140748
09/2026
: https://doi.org/10.1016/j.physletb.2026.140748
: WOS:001847476100001
High Energy Physics - Experiment Physics
A search for charged lepton flavour violation inτ→ 3μdecays is performed inppcollisions at a centre-of-mass energy of 13 TeV using ATLAS data collected between 2016 and 2018, corresponding to an integrated luminosity of 137\text{fb}{⁻¹}{} . The search focuses on the electroweakW → τνproduction channel. 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 ratioB(τ→3μ)is found to be8.7× 10⁻⁸( 7.5× 10⁻⁸ ) at90%CL.
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