Direct CP violation in Cabibbo-favored charmed meson decays and ϵ′/ϵ in SU(2)L × SU(2)R × U(1)B−L model

Abstract

Abstract Since the standard model contribution is virtually absent, any observation of direct CP violation in the Cabibbo-favored charmed meson decays would be evidence of new physics. In this paper, we conduct a quantitative study on direct CP violation in D 0 → K − π +, D s +  → ηπ + and D s +  → η′π + decays in the SU(2) L ×SU(2) R ×U(1) B−L gauge extension of the standard model. In the model, direct CP violation arises mainly from the interference between the decay amplitude coming from the SM left-left current operators and that from the right-right current operators induced by W R + gauge boson exchange. Interestingly, the strong phase between the two amplitudes is evaluable, since it stems from difference in QCD corrections to the left-left and right-right current operators, which is a short-distance QCD effect given by $$ \sim \left({\alpha}_s\left({M}_{W_L}^2\right)/4\pi \right) \log \left({M}_{W_R}^2/{M}_{W_L}^2\right) $$ ∼ α s M W L 2 / 4 π log M W R 2 / M W L 2 . We assess the maximal direct CP violation in the above decays in the SU(2) L × SU(2) R × U(1) B−L model. Additionally, we present a correlation between direct CP violation in these modes and one in K → ππ decay parametrized by ϵ′, since W R + gauge boson has a sizable impact on the latter.