Resonant CP Violation due to Heavy Neutrinos at the LHC

Abstract

The observed light neutrinos may be related to the existence of new heavy neutrinos in the spectrum of the SM. If a pair of heavy neutrinos has nearly degenerate masses, then CP violation from the interference between tree-level and self-energy graphs can be resonantly enhanced. We explore the possibility of observing CP asymmetries due to this mechanism at the LHC. We consider a pair of heavy neutrinos N_{1,2} with masses ranging from 100 to 500 GeV and a mass-splitting Δm_N = m_{N_2}-m_{N_1} comparable to their widths Γ_{N_{1,2}}. We find that for Δm_N ~ Γ_{N_{1,2}}, the resulting CP asymmetries can be very large or even maximal and therefore, could potentially be observed at the LHC.