Resonant CP violation in rare τ ± decays

Abstract In this work, we study the lepton number violating tau decays via intermediate on-shell Majorana neutrinos N j into two scalar mesons and a lepton τ ± → M 1 ± N j → M 1 ± M 2 ± ℓ ∓. We calculate the Branching ratios Br(τ ±) and the CP asymmetry (Γ(τ +) − Γ(τ −))/(Γ(τ +) + Γ(τ −)) 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(τ ±) when their mass difference is similar with their decay width ΔM N ∼ Γ N . We also present regions of the heavy-light neutrino mixing elements, in which the CP asymmetry could be explored in future tau factories