Evidence for tWZ production in proton-proton collisions at $\sqrt{s} = 13~\mathrm{TeV}$ in multilepton final states

We present the first evidence for the standard model production of a top quark in association with a $\mathrm{W}$ and a $\mathrm{Z}$ boson in multilepton final states. The $\mathrm{Z}$ boson is reconstructed via its decays to electron or muon pairs. The analysed data were recorded by the CMS experiment at the CERN LHC from 2016 to 2018 in proton-proton collisions at $\sqrt{s} = 13~\mathrm{TeV}$, and correspond to an integrated luminosity of $138~\mathrm{fb}^{-1}$. The measured cross section amounts to $0.37\pm0.05\,\mathrm{(stat)}\pm0.10\,\mathrm{(syst)}~\mathrm{pb}$, and corresponds to an observed (expected) significance of $3.5$ ($1.4$) standard deviations.$$\textit{This document has been revised with respect to the version dated April 23, 2023.}$$