2026/05/24 by CMS Collaboration · 1 voice
Physics and Astronomy · #hep-ex
Decays of Z bosons to four charged leptons (electrons and muons) are studied in proton-proton collisions at √(s) = 8 and 13 TeV. The analysis is based on data collected with the CMS detector at the LHC corresponding to an integrated luminosity of 19.7 fb-1 at 8 TeV and 138 fb-1 at 13 TeV. The measured value of the inclusive branching fraction for all four-lepton decay modes, B(Z → 4ℓ), is [4.67 ± 0.11 (stat) ± 0.10 (syst)] × 10-6, which has a precision of about 3% limited by both statistical and systematic uncertainties. Measurements of the individual branching fractions for the decays Z → 4μ, Z → 4e, and Z → 2μ2e are also reported. Differential decay rates are presented as functions of kinematic and angular quantities in the Z boson rest frame. Measurements of triple-product asymmetries, which are sensitive to possible violations of charge conjugation and parity invariance, are performed for Z → 4ℓ decays. The results are compared with standard model predictions and used to set limits on the production of new gauge bosons.