Search for a new Z′ gauge boson via the pp→W^±(∗)→Z′μ^±ν→μ^±μ^∓μ^±ν process in pp collisions at √s = 13 TeV with the ATLAS detector

A search for a new Z′ gauge boson predicted by L_μ−L_τ models, based on charged-current Drell-Yan production, pp→W^±(∗)→Z′μ^±ν→μ^±μ^∓μ^±ν, is presented. The data sample used corresponds to an integrated luminosity of 140 fb⁻¹ of proton-proton collisions at √s = 13 TeV recorded by the ATLAS detector at the Large Hadron Collider. The search examines a final state of 3μ plus large missing transverse momentum. Upper limits are set on the Z′ production cross-section times branching ratio in the mass range of 5-81 GeV. After combining with the previous Z′ search using the neutral-current Drell-Yan production with a 4μ final state, the most stringent exclusion limits to date are achieved in the parameter space of the Z′ coupling strength and mass.