Anatomy of $B_s \to PV $ decays and effects of next-to-leading order contributions in the perturbative QCD factorization approach

TL;DR

This paper systematically calculates branching ratios and CP asymmetries for 21 $ar{B}_s^0 o PV$ decays using perturbative QCD, incorporating NLO contributions to improve agreement with experimental data.

Contribution

It provides the first comprehensive NLO analysis of $ar{B}_s^0 o PV$ decays within the PQCD framework, including detailed effects on form factors and decay amplitudes.

Findings

NLO contributions enhance some branching ratios by ~40%.

Inclusion of NLO effects improves agreement with experimental measurements.

Interference effects explain differences in decay predictions.

Abstract

In this paper, we will make systematic calculations for the branching ratios and the CP-violating asymmetries of the twenty one $\bar{B}^0_s \to PV $ decays by employing the perturbative QCD (PQCD) factorization approach. Besides the full leading-order (LO) contributions, all currently known next-to-leading order (NLO) contributions are taken into account. We found numerically that: (a) the NLO contributions can provide $\sim 40\%$ enhancement to the LO PQCD predictions for ${\cal B}(\bar{B}_s^0 \to K^0 \bar{K}^{*0})$ and $ {\cal B}(\bar{B}_s^0 \to K^{\pm}K^{*\mp})$, or a $\sim 37\% $ reduction to $ \calb(\bar{B}_s^0 \to \pi^{-} K^{*+})$, and we confirmed that the inclusion of the known NLO contributions can improve significantly the agreement between the theory and those currently available experimental measurements, (b) the total effects on the PQCD predictions for the relevant $B\to P$ transition form factors after the inclusion of the NLO twist-2 and twist-3 contributions is generally small in magnitude: less than $ 10\%$ enhancement respect to the leading order result, (c) for the "tree" dominated decay $\bar B_s^0\to K^+ \rho^- $ and the "color-suppressed-tree" decay $\bar B_s^0\to \pi^0 K^{*0}$, the big difference between the PQCD predictions for their branching ratios are induced by different topological structure and by interference effects among the decay amplitude ${\cal A}_{T,C}$ and ${\cal A}_P$: constructive for the first decay but destructive for the second one, and (d) for $\bar{B}_s^0 \to V(\eta, \etar)$ decays, the complex pattern of the PQCD predictions for their branching ratios can be understood by rather different topological structures and the interference effects between the decay amplitude $\cala(V\eta_q)$ and $\cala(V\eta_s)$ due to the $\eta-\etar$ mixing.