Evidence for the production of three massive vector bosons with the ATLAS detector

Abstract

A search for the production of three massive vector bosons in proton–proton collisions is performed using data at √s=13TeV recorded with the ATLAS detector at the Large Hadron Collider in the years 2015–2017, corresponding to an integrated luminosity of 79.8fb⁻¹. Events with two same-sign leptons l (electrons or muons) and at least two reconstructed jets are selected to search for WWW→ lνlνqq. Events with three leptons without any same-flavour opposite-sign lepton pairs are used to search for WWW→ lνlνlν, while events with three leptons and at least one same-flavour opposite-sign lepton pair and one or more reconstructed jets are used to search for WWZ→ lνqqll. Finally, events with four leptons are analysed to search for WWZ→ lνlνll and WZZ→qqllll. Evidence for the joint production of three massive vector bosons is observed with a significance of 4.1 standard deviations, where the expectation is 3.1 standard deviations.