A search for flavor violating decays of the Z boson to charged leptons is performed using data from proton-proton collisions at root s = 13 TeV collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb(-1). Each of the decays Z -> e mu, Z -> e tau, and Z -> mu tau is considered. The data are consistent with the backgrounds expected from standard model processes. For the Z -> e mu channel the observed (expected) 95% confidence level upper limit on the branching fraction is 1.9(2.0) x 10(-7), which is the most stringent direct limit to date on this process; the corresponding limits for the Z -> e tau and Z -> mu tau channels are 13.8(11.4) x 10(-6) and 12.0(5.3) x 10(-6), respectively. Additionally, the e mu final state is used to search for lepton flavor violating decays of Z' resonances in the mass range from 110 to 500 GeV. No significant excess is observed above the predicted background levels.

Search for charged lepton flavor violating Z and Z0 boson decays in proton-proton collisions at ffiffis p = 13 TeV ′

Alexe, C.;Bruschini, D.;Ligabue, F.;
2025

Abstract

A search for flavor violating decays of the Z boson to charged leptons is performed using data from proton-proton collisions at root s = 13 TeV collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb(-1). Each of the decays Z -> e mu, Z -> e tau, and Z -> mu tau is considered. The data are consistent with the backgrounds expected from standard model processes. For the Z -> e mu channel the observed (expected) 95% confidence level upper limit on the branching fraction is 1.9(2.0) x 10(-7), which is the most stringent direct limit to date on this process; the corresponding limits for the Z -> e tau and Z -> mu tau channels are 13.8(11.4) x 10(-6) and 12.0(5.3) x 10(-6), respectively. Additionally, the e mu final state is used to search for lepton flavor violating decays of Z' resonances in the mass range from 110 to 500 GeV. No significant excess is observed above the predicted background levels.
2025
Settore PHYS-01/A - Fisica sperimentale delle interazioni fondamentali e applicazioni
   Advanced Multi-Variate Analysis for New Physics Searches at the LHC
   AMVA4NewPhysics
   European Commission
   Horizon 2020 Framework Programme
   675440

   Direct and indirect searches for new physics in events with top quarks using LHC proton-proton collisions at the CMS detector
   LHCTOPVLQ
   European Commission
   Horizon 2020 Framework Programme
   752730

   Majorana neutrino discovery strategy with CMS
   MajorNet
   European Commission
   Horizon 2020 Framework Programme
   758316
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/160546
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