Search for heavy resonances and quantum black holes in e$\mu$, e$\tau$, and $\mu\tau$ final states in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A search is reported for heavy resonances and quantum black holes decaying
into eµ, eτ, and µτ final states in proton-proton collision data recorded by the CMS experiment at the CERN LHC during 2016–2018 at √
s = 13 TeV, corresponding to an integrated
luminosity of 138 fb−1
. The eµ, eτ, and µτ invariant mass spectra are reconstructed, and
no evidence is found for physics beyond the standard model. Upper limits are set at 95%
confidence level on the product of the cross section and branching fraction for lepton flavor
violating signals. Three benchmark signals are studied: resonant τ sneutrino production
in R parity violating supersymmetric models, heavy Z0
gauge bosons with lepton flavor
violating decays, and nonresonant quantum black hole production in models with extra
spatial dimensions. Resonant τ sneutrinos are excluded for masses up to 4.2TeV in the eµ
channel, 3.7TeV in the eτ channel, and 3.6TeV in the µτ channel. A Z0
boson with lepton
flavor violating couplings is excluded up to a mass of 5.0TeV in the eµ channel, up to 4.3Te
V in the eτ channel, and up to 4.1TeV in the µτ channel. Quantum black holes in the
benchmark model are excluded up to the threshold mass of 5.6TeV in the eµ channel, 5.2Te
V in the eτ channel, and 5.0TeV in the µτ channel. In addition, model-independent limits
are extracted to allow comparisons with other models for the same final states and similar
event selection requirements. The results of these searches provide the most stringent limits
available from collider experiments for heavy particles that undergo lepton flavor violating
decays.