B0d,s→f1f1 decays with f1(1285)-f1(1420) mixing in the perturbative QCD approach.

We investigate the B0d,s→f1f1 decays in the framework of perturbative QCD (PQCD) approach with a referenced value ϕf1∼24°. Here, f1 denotes the axial-vector mesons f1(1285) and f1(1420) with mixing angle ϕf1 in the quark-flavor basis. The observables such as branching ratios, direct CP violations, and polarization fractions of the B0s→f1f1 decays are predicted for the first time. We find that (i) the almost pure penguin modes B0s→f1f1 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 B0s→fnfs and B0s→fsfs with fn and fs being the quark-flavor states of f1 mesons. (ii) The observables receive important contributions from the weak annihilation diagrams in the PQCD approach. In particular, without the annihilation contributions, the B0s→f1(1420)f1(1420) branching ratio will decrease about 81% and its longitudinal polarization fraction will reduce around 43%. And (iii) the dependence of the B0d,s→f1f1 decay rates on ϕf1 exhibits some interesting line shapes, whose confirmations would be helpful to constrain the determination of ϕf1 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. [ABSTRACT FROM AUTHOR]