A first search is presented for vector-like leptons (VLLs) exclusively decaying into a light long-lived pseudoscalar boson and a standard model tau lepton. The pseudoscalar boson is assumed to have a mass below the tau(+)tau(-) threshold, so that it decays exclusively into two photons. It is identified using the CMS muon system. The analysis is carried out using a data set of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment in 2016-2018, corresponding to an integrated luminosity of 138 fb(-1). Selected events contain at least one pseudoscalar boson decaying electromagnetically in the muon system and at least one hadronically decaying tau lepton. No significant excess of data events is observed compared to the background expectation. Upper limits are set at 95% confidence level on the vector-like lepton production cross section as a function of the VLL mass and the pseudoscalar boson mean proper decay length. The observed and expected exclusion ranges of the VLL mass extend up to 700 and 670 GeV, respectively, depending on the pseudoscalar boson lifetime.

Search for vector-like leptons with long-lived particle decays in the CMS muon system in proton-proton collisions at $$\sqrt{\text{s}}$$ = 13 TeV

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

Abstract

A first search is presented for vector-like leptons (VLLs) exclusively decaying into a light long-lived pseudoscalar boson and a standard model tau lepton. The pseudoscalar boson is assumed to have a mass below the tau(+)tau(-) threshold, so that it decays exclusively into two photons. It is identified using the CMS muon system. The analysis is carried out using a data set of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment in 2016-2018, corresponding to an integrated luminosity of 138 fb(-1). Selected events contain at least one pseudoscalar boson decaying electromagnetically in the muon system and at least one hadronically decaying tau lepton. No significant excess of data events is observed compared to the background expectation. Upper limits are set at 95% confidence level on the vector-like lepton production cross section as a function of the VLL mass and the pseudoscalar boson mean proper decay length. The observed and expected exclusion ranges of the VLL mass extend up to 700 and 670 GeV, respectively, depending on the pseudoscalar boson lifetime.
2025
Settore PHYS-01/A - Fisica sperimentale delle interazioni fondamentali e applicazioni
Beyond Standard Model; Hadron-Hadron Scattering; Lepton Production; Tau Physics;
   INnovative TRiggEr techniques for beyond the standard model PhysIcs Discovery at the LHC
   INTREPID
   European Commission
   Horizon Europe Framework Programme
   101115353

   Fundamental properties and time-scan of QCD matter at high densities and temperature exposed by jet substructure in heavy ion collisions with CMS experiment at the LHC
   QCDHighDensityCMS
   European Commission
   Horizon 2020 Framework Programme
   101002207

   The strong interaction at the frontier of knowledge: fundamental research and applications
   STRONG-2020
   European Commission
   Horizon 2020 Framework Programme
   824093
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/156547
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