Heavy Majorana neutrinos from Wγ fusion at hadron colliders

Vector boson fusion processes become increasingly more important at higher collider energies and for probing larger mass scales due to collinear logarithmic enhancements of the cross section. In this context, we revisit the production of a hypothetic heavy Majorana neutrino (N) at hadron colliders. Particular attention is paid to the fusion process W gamma -> Nl(+/-). We systematically categorize the contributions from a photon initial state in the elastic, inelastic, and deeply inelastic channels. Comparing with the leading channel via the Drell-Yan production q (q) over bar' -> W* -> Nl(+/-) at NNLO in QCD, we find that the W gamma fusion process becomes relatively more important at higher scales, surpassing the DY mechanism at m(N) similar to 1 TeV (770 GeV), at the 14TeV LHC (100TeV VLHC). We investigate the inclusive heavy Majorana neutrino signal, including QCD corrections, and quantify the Standard Model backgrounds at future hadron colliders. We conclude that, with the currently allowed mixing vertical bar V-mu N vertical bar(2) < 6 x 10(-3), a 5 sigma discovery can be made via the same-sign dimuon channel for m(N) = 530 (1070) GeV at the 14TeV LHC (100TeV VLHC) after 1 ab(-1). Reversely, for m(N) = 500GeV and the same integrated luminosity, a mixing vertical bar V-mu N vertical bar(2) of the order 1.1 x 10(-3) (2.5 x 10(-4)) may be probed.