Improved Estimates of The $B_{(s)}\to V V$ Decays in Perturbative QCD Approach

TL;DR

This paper refines predictions for $B_{(s)} o VV$ decays using an updated perturbative QCD approach, incorporating recent data and power corrections, and compares results with QCD factorization to enhance understanding of decay mechanisms.

Contribution

The work introduces improved estimates of decay observables in $B_q o VV$ decays by including updated distribution amplitudes and power corrections, providing a more accurate theoretical framework.

Findings

Updated calculations agree with most experimental data.

Penguin annihilation and hard-scattering are key to polarization anomalies.

Comparison with QCDF highlights differences for future tests.

Abstract

We reexamine the branching ratios, $CP$-asymmetries, and other observables in a large number of $B_q\to VV(q=u,d,s)$ decays in the perturbative QCD (PQCD) approach, where $V$ denotes a light vector meson $(\rho, K^*, \omega, \phi)$. The essential difference between this work and the earlier similar works is of parametric origin and in the estimates of the power corrections related to the ratio $r_i^2=m_{V_i}^2/m_B^2(i=2,3)$ ($m_V$ and $m_B$ denote the masses of the vector and $B$ meson, respectively). In particular, we use up-to-date distribution amplitudes for the final state mesons and keep the terms proportional to the ratio $r_i^2$ in our calculations. Our updated calculations are in agreement with the experimental data, except for a limited number of decays which we discuss. We emphasize that the penguin annihilation and the hard-scattering emission contributions are essential to understand the polarization anomaly, such as in the $B\to \phi K^*$ and $B_s \to \phi\phi$ decay modes. We also compare our results with those obtained in the QCD factorization (QCDF) approach and comment on the similarities and differences, which can be used to discriminate between these approaches in future experiments.