Bd,s0→f1f1 decays with f1(1285)?f1(1420) mixing in the perturbative QCD approach

摘要

We investigate the B d , s 0 → f 1 f 1 decays in the framework of perturbative QCD (PQCD) approach with a referenced value ? f 1 ～ 24 ° . Here, f 1 denotes the axial-vector mesons f 1 ( 1285 ) and f 1 ( 1420 ) with mixing angle ? f 1 in the quark-flavor basis. The observables such as branching ratios, direct C P violations, and polarization fractions of the B s 0 → f 1 f 1 decays are predicted for the first time. We find that (i)?the almost pure penguin modes B s 0 → f 1 f 1 have large branching ratios in the order of 10 ? 6 ～ 10 ? 5 due to the Cabibbo-Kobayashi-Maskawa enhancement and generally constructive interferences between the amplitudes of B s 0 → f n f s and B s 0 → f s f s with f n and f s being the quark-flavor states of f 1 mesons. (ii)?The observables receive important contributions from the weak annihilation diagrams in the PQCD approach. In particular, without the annihilation contributions, the B s 0 → f 1 ( 1420 ) f 1 ( 1420 ) branching ratio will decrease about 81% and its longitudinal polarization fraction will reduce around 43%. And (iii)?the dependence of the B d , s 0 → f 1 f 1 decay rates on ? f 1 exhibits some interesting line shapes, whose confirmations would be helpful to constrain the determination of ? f 1 inversely. All the PQCD predictions await for the (near) future examinations at Large Hadron Collider beauty and/or Belle-II experiments to further understand the properties of the axial-vector mesons and the perturbative dynamics released from the considered decay modes.