The Direct CP Violation In The Decay Process Of B_c Meson Via ?-? Mixing

Since the 80 s of last century,the heavy flavor physics has achieved great development in both theory and experiment.With the B meson experiments carried out smoothly from America and Japan,B meson physics has become a hot topic of particle physics.It is well known that the cB meson is the double heavy meson which is consist of a heavy b quark and a heavy c quark.It has rich decay channels,which provide a ideal place to test Standard Model,search CP violation and explore the new physics beyond the standard model.It is theoretically difficult to deal with the calculation of hadronic matrix elements,based on transparent mechanism and QCD correction.People put forward: naive factorization,QCD factorization approacn,pQCD factorization approach,SCET and so on.Staring from the basic low energy effective hamiltonian,the paper introduces a brief review for the operator product expansion,the four-quark operator and the different factorization approaches.We also talk about the pQCD approach and the ?-? mixing mechanism.In this paper,we study of the direct CP violation in the decay processes of B_c~+?D~+0?~0(?)?D~+?~+?~- and B_c~+?D_s~+?~0 (?)?D_s~+?~+?~- including the effect of ?-? mixing within pQCD scheme.We find that the CP violation can be enhanced greatly via the ?-? mixing mechanism when the invariant mass of ?~+?~- pair is in the vicinity of the w resonance.For the process of b?d transition,the CP violating asymmetries for the decay process of B_c~+?D~+?~+?~- can be enhanced about 7.33%;while for the process of b?s transition,CP violating asymmetries for the decay process of B_c~+?D_s~+?~+?~- can reach about 7.05%.At the end of the article,summarizes and prospects are presented.