Heavy Majorana neutrino pair production from Z′ at hadron and lepton colliders

A gauged U(1) extension of the Standard Model (SM) is a simple and anomaly-free framework where three generations of Majorana type right-handed neutrinos (RHNs) are introduced to generate light neutrino mass and flavor mixings through the seesaw mechanism. We investigate such models at different hadron and lepton colliders via Z′ induced Majorana type RHNs pair production. We derive bounds on U(1) gauge coupling (g′) comparing the model cross sections with experimentally observed data for different Z′ mass (MZ′) and RHNs mass (MN). Using these limits we estimate the allowed RHN pair production cross section which can be manifested by lepton number violating signatures in association with fat-jets at the hadron colliders depending on the mass of the RHNs. Hence we study dilepton and trilepton modes with fat-jet/s of the signal for different benchmark values of MZ′ and MN. Using fat-jet signatures and studying the signal and corresponding SM backgrounds, we estimate bounds on MN-MZ′ plane at different center of mass energies which could be probed at different hadron colliders. In the context of the lepton colliders we consider electron positron initial states where Majorana type RHNs can be produced from Z′ manifesting same sign dilepton plus jets signature and trilepton plus jets in association with missing energy. Studying the signal and corresponding SM backgrounds we estimate the bounds on the MN-MZ′ plane for different center of mass energies. In the context of the U(1) extension of the SM there is a SM singlet BSM scalar which couples with the RHNs. We can probe the Majorana nature of RHNs via this BSM scalar production at electron positron colliders.