Direct CP violation in Cabibbo-favored charmed meson decays and \u03f5\u2032/\u03f5 in SU(2)L \xd7 SU(2)R \xd7 U(1)B\u2212L model

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 D0 → K−π+, Ds+ → ηπ+ and Ds+ → 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 WR+ 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}_sleft({M}_{W_L}^2right)/4pi right) log left({M}_{W_R}^2/{M}_{W_L}^2right) . 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 WR+ gauge boson has a sizable impact on the latter.