CHIPP/CHART Workshop on Sustainability in Particle Physics and CHIPP 2023 plenary

The rare decay of the Z→2τ2μ

15 Jun 2023, 20:15

5m

Poster CHIPP/CHART

Speaker

Mr Fanqiang Meng (University of Zurich)

Description

The first search for the Z boson decay to $\tau \tau \mu \mu$ is presented. The data analyzed were collected by the CMS experiment at the CERN LHC in proton-proton collisions at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of 138 ${\mathrm{fb}}^{-1}$. Targeting tau lepton decays to muons and the corresponding
neutrinos, events with two pairs of oppositely charged muons are analyzed. The data are found to be compatible with the predicted background. An upper limit of 6.9 times the standard model expectation is placed on the ratio of event yields from the $\mathrm{Z}\to \tau \tau \mu \mu$ and $\mathrm{Z}\to \mu \mu \mu \mu$ decays, which corresponds to an upper limit on the ratio of branching fractions of these decay modes of 6.2.