Quasi-two-body decays Bc → K*h → Kπh in perturbative QCD

摘要

In this work, we study the quasi-two-body decays Bc -> K*h -> K pi h(h = D; Ds; K; pi;eta;eta 0) in the perturbative QCD (PQCD) approach. The two-meson distribution amplitudes phi P-wave K pi are introduced to describe the final-state interactions of the K pi pair, which involve the timelike form factors FK pi(s) parametrized by the relativistic Breit-Wigner function and the Gegenbauer polynomials. We calculate the branching ratios for these quasi-two-body decays, from which one can obtain the branching ratios for the corresponding two-body decays under the narrow width approximation relation. We find that B+c -> K*+D0 and B+c -> K*0D+ have the largest branching ratios, which can reach up to 10-6, while the branching ratios for other two-body decays are very small and only about 10-8 - 10-7. As we expected, the branching ratios of the pure annihilation decays are usually small, while in our considered such type of decays, the channel B+c -> over bar K*0K+ has the largest branching ratio, which is near 10-6. These results are consistent with the previously PQCD calculations obtained in the two-body framework, which can be tested by future LHCb experiments. For the decays B+c -> K*+D0 -> K0 pi+D0, B+c -> K*0D+ -> K+pi-D+, and B+c -> over bar K*0D+s -> K-pi+D+s , we also calculate their direct CP violations and find that ACP(B+c -> K*+D0 -> K0 pi+D0) = (-14.6+9.2 -1.1 )% is the largest one, which is possible measured by the present LHCb experiments. For the pure annihilation type decays, there is no CP violation, because only the tree operators are involved. Furthermore, we give the differential distributions of the branching ratios and the direct CP violations in the K pi invariant mass omega for the decays Bc -> K*D(s) -> K pi D(s).

关键词