Pure annihilation type B-c -> M2M3 decays in the perturbative QCD approach

In the standard model the two-body charmless hadronic B-c meson decays can occur via annihilation diagrams only. In this work, we studied the B-c -> PP, PV/VP, VV decays by employing the perturbative QCD (pQCD) factorization approach. From our calculations, we find that (a) the pQCD predictions for the branching ratios of the considered B-c decays are in the range of 10(-6) to 10(-8); (b) for B-c -> PV/VP, VV decays, the branching ratios of Delta S = 0 decays are much larger than those of Delta S = 1 because the different Cabibbo-Kobayashi-Maskawa (CKM) factors are involved; (c) analogous to B -> K eta((t)) decays, we find Br(B-c -> K+eta') similar to 10 X Br(B-c -> K+eta), which can be understood by the destructive and constructive interference between the eta(q) and eta(s) contribution to the B-c -> K+eta and B-c -> K+eta' decay; (d) the longitudinal polarization fractions of B-c -> VV decays are in the range of 86%-95% and play the dominant role; and (e) there is no CP-violating asymmetries for the considered B-c decays because only one type tree operator is involved.