Heavy Neutral Leptons in Gauged U(1)_L_μ-L_τ at Muon Collider

Heavy neutral leptons N are the most appealing candidates to generate the tiny neutrino masses. In this paper, we study the signature of heavy neutral leptons in gauged U(1)_L_μ-L_τ at a muon collider. Charged under the U(1)_L_μ-L_τ symmetry, the heavy neutral leptons can be pair produced via the new gauge boson Z' at muon collider as μ^+μ^-→ Z^' *→ NN and μ^+μ^-→ Z^' (*)γ→ NNγ. We then perform a detailed analysis on the lepton number violation signature μ^+μ^-→ NN→μ^±μ^± W^∓ W^∓ and μ^+μ^-→ NN γ→μ^±μ^± W^∓ W^∓γ at the 3 TeV muon collider, where the hadronic decays of W boson are treated as fat-jets J. These lepton number violation signatures have quite clean backgrounds at the muon collider. Our simulation shows that a wide range of viable parameter space is within the reach of the 3 TeV muon collider. For instance, with new gauge coupling g'=0.6 and an integrated luminosity of 1000 fb^-1, the μ^±μ^± JJ signal could probe m_Z'≲ 12.5 TeV. Meanwhile, if the gauge boson mass satisfies 2 m_N更多