# Search for Lepton Flavour Violating $\tau\rightarrow 3 \mu$ decays in $W\rightarrow \tau \nu$ events with 2016 CMS data.

Fiorendi S., Guzzi L., Malvezzi S., Manzoni R., Verzetti M.

Comunicazione
I - Fisica nucleare e subnucleare
Aula 32C-3 - Giovedì 20 h 16:30 - 19:00
Lepton Flavour Violating processes, strongly suppressed in the Standard Model, provide a promising field of research for new physics: a number of BSM models predict branching fraction at the level of 10-10 10-8 for $\tau\rightarrow 3 \mu$ i.e within the reach of the current experimental sensitivity. At CMS an analysis is performed on $\tau\rightarrow 3 \mu$,$exploiting the characteristic signature of$W\rightarrow \tau \nu$,$ consisting of a high pT lepton and large missing ET. The analysis is conducted on 2016 data, selected by a dedicated trigger (33 fb-1). An expected limit of $1.1 \times 10^{-7}$ (at 90% CL) is estimated using multivariate techniques. This is the first CMS analysis of this channel.