The Majorana nature of neutrinos is one of the most fundamental questions in particle physics. It is directly related to the violation of accidental lepton number symmetry. This motivated enormous efforts into the search of such processes; among them, one conventional experiment is the neutrinoless double-beta decay ($0\nu \beta \beta$). On the other hand, there have been proposals of future electron-positron colliders as a “Higgs factory" for the precise measurement of Higgs boson properties, and it has been proposed to convert such a machine into an electron-electron collider. This option enables a new way to probe TeV Majorana neutrinos via the inverse $0\nu \beta \beta$ decay process ($e^{-}{e}^{-}\to W^{-}{W}^{-}$) as an alternative and complementary test to the conventional $0\nu \beta \beta$ decay experiments. In this paper, we investigate the collider search for $e^{-}{e}^{-}\to W^{-}{W}^{-}$ in different decay channels at future electron colliders. We find that the pure hadronic channel, the semileptonic channel with a muon, and the pure leptonic channel with a dimuon have the most discovery potential.

• Received 14 October 2016

DOI:https://doi.org/10.1103/PhysRevD.95.075021