Study of Bs0→TT(a2(1320), K2*(1430), f2(1270), f2′(1525)) in the perturbative QCD approach

Abstract

In the present study, the calculations of two-body decays Bs0→TT [T denotes tensor mesons, a2(1320), K2*(1430), f2(1270), f2′(1525)] in the perturbative QCD approach are presented. The ensuing predictions encompass branching ratios, polarization fractions, and direct CP violations, all elucidated in comprehensive detail. It is discerned that (1) for pure annihilation decay, the longitudinal polarization is around 90.0%, whereas the transverse polarizations manifest comparatively diminutive magnitudes. (2) The direct CP asymmetry is directly proportional to the interference between the tree and penguin contributions. For most of the decays investigated within this discourse, the direct CP asymmetry remains modest in magnitude. (3) There are precisely six distinct categories of Feynman diagrams for Bs0→TT, because the tensor mesons cannot be produced through the (V±A) currents or (S±P) density, thereby prohibiting factorizable emission diagrams. The nonfactorizable and annihilation contributions are ascertained to be pivotal in these decay modes. The calculated branching ratios of our calculation for Bs0→TT are at the order of 10−6 and 10−7, which can be tested in the LHCb and Belle II experiments. (4) Mixing exists for the f2(1270) and f2′(1525), just as the η and η′ mixing, the branching ratios about the mixing angle θ are given in this work. However, it is different from f1(1285)−f1(1420), the mixing angle is notably small, thereby resulting in only marginal alterations in the decay branching ratios. Published by the American Physical Society 2024