Measuring CP violation in rare $W$ decays at the LHC

Abstract

Heavy Majorana neutrinos beyond the standard model can simultaneously explain the origin of tiny neutrino masses and matter-antimatter asymmetry in our Universe. The existence of heavy Majorana neutrinos will also lead to lepton number violation and the rare lepton-number-violating $W$ decays are possible. With contributions from two different Majorana neutrinos, a nonzero CP asymmetry may be generated from the rate difference between $W$ decay and its CP-conjugate process. The aim of this paper is to investigate the prospects for measuring CP violation in rare $W$ decays via Majorana neutrinos at the LHC. Our calculations show that the induced CP asymmetry is independent of the Majorana neutrino mass for $10\mathrm{GeV}<{\mathrm{m}}_{\mathrm{N}}<70\mathrm{GeV}$. Such a CP asymmetry if observed, would in turn provide unambiguous evidence of new physics beyond the standard model.

Comments: 15 pages,6 Figures, 1 Table