CMS logoCMS event Hgg
Compact Muon Solenoid
LHC, CERN

CMS-PAS-BPH-21-005
Search for lepton flavor violating $ \tau \!\to\! $ 3$\mu $ decays in proton-proton collisions at $ \sqrt{s} $ = 13 TeV
Abstract: A search for lepton flavor violating $ \tau\to $ 3$\mu $ decays is performed using 97.7 fb$ ^{-1} $ of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment at the LHC in 2017 and 2018. Tau leptons produced in heavy-flavor hadron decays and produced in W boson decays are exploited in the analysis. The results of this search are combined with the previous result based on data collected in 2016, to obtain a total integrated luminosity of 131 fb$ ^{-1} $. The observed (expected) upper limit at 90% confidence level on the branching fraction $ \mathcal{B}(\tau\to3\mu) $ is 2.9 $ \times$ 10$^{-8} $ (2.4 $ \times $ 10$^{-8} $). The observed (expected) upper limit at 95% confidence level on the branching fraction $ \mathcal{B}(\tau\to3\mu) $ is 3.6 $ \times $ 10$^{-8} $ (3.0 $ \times $ 10$^{-8} $).
CMS Publications
Compact Muon Solenoid
LHC, CERN