Evidence for tWZ production in proton-proton collisions at TeV in multilepton final states

The first evidence for the standard model production of a top quark in association with a W boson and a Z boson is reported. The measurement is performed in multilepton final states, where the Z boson is reconstructed via its decays to electron or muon pairs. At least one W boson, associated or from top quark decay, decays leptonically, too. The analysed data were recorded by the CMS experiment at the CERN LHC in 2016–2018 in proton-proton collisions at $\sqrt{s}=13$ TeV, and correspond to an integrated luminosity of 138 fb$^{−1}$. The measured cross section is $354±54\left(\text{stat}\right)±95\left(\text{syst}\right)$ fb, and corresponds to a statistical significance of 3.4 standard deviations.