Resonant CP violation in rare τ± decay

In this work, we study the lepton number violating tau decays via intermediate on-shell Majorana neutrinos Nj into two scalar mesons and a lepton tau(+/-) -> M-1(+/-) N-j -> (M1M2 +/-)-M-+/- l(-/+). We calculate the Branching ratios Br(tau(+/-)) and the CP asymmetry (Gamma(tau(+)) - Gamma(tau(-)))/(Gamma(tau(+)) + Gamma(tau(-)) for such decays, in a scenario that contains at least two heavy Majorana neutrinos. The results show that the CP asymmetry is small, but becomes comparable with the branching ratio Br(tau(+/-)) when their mass difference is similar with their decay width Delta M-N similar to Gamma(N). We also present regions of the heavy-light neutrino mixing elements, in which the CP asymmetry could be explored in future tau factories.