Title: Anatomy of $B_s \to VV $ decays and effects of next-to-leading order contributions in the perturbative QCD factorization approach Show Chinese title

Title: $B_s \to VV $衰变的结构及微扰QCD因子化方法中次领头阶贡献的影响

Abstract: By employing the perturbative QCD (PQCD) factorization approach, we calculated the branching ratios, CP-violating asymmetries, the longitudinal and transverse polarization fractions and other physical observables of the thirteen charmless hadronic $\bar{B}^0_s \to V V $ decays with the inclusion of all currently known next-to-leading order (NLO) contributions. We focused on the examination of the effects of all those currently known NLO contributions and found that: (a) for the measured decays $\bar{ B}_s^0 \to \phi \phi, K^{*0} \phi,\bar K^{*0} K^{*0}$ and $\rho^0 \phi$, the NLO contributions can provide $\sim 20\%$ to $\sim 40\%$ enhancements to the leading order (LO) PQCD predictions of their CP-averaged branching ratios, and consequently the agreement between the PQCD predictions and the measured values are improved effectively after the inclusion of the NLO contributions; (b) for the measured decays, the NLO corrections to the LO PQCD predictions for $(f_L,f_\perp)$ and $(\phi_{\|},\phi_{\bot})$ are generally small in size, but the weak penguin annihilation contributions play an important role in understanding the data about their decay rates, $f_L$ and $f_\perp$; (c) the NLO PQCD predictions for above mentioned physical observables do agree with the measured ones and the theoretical predictions from the QCDF, SCET and FAT approaches; (d) for other considered $B_s^0 \to VV$ decays, the NLO PQCD predictions for their decay rates and other physical observables are also basically consistent with the theoretical predictions from other popular approaches, future precision measurements could help us to test or examine these predictions. Show Chinese abstract

Abstract: 通过采用微扰量子色动力学（PQCD）因子化方法，我们计算了包含所有目前已知的下一阶（NLO）贡献的十三种无 charm 重子$\bar{B}^0_s \to V V $衰变的分支比、CP破坏不对称性、纵向和横向极化分数及其他物理可观测量。 我们重点考察了所有目前已知的非微扰效应的影响，并发现：(a) 对于测量的衰变$\bar{ B}_s^0 \to \phi \phi, K^{*0} \phi,\bar K^{*0} K^{*0}$和$\rho^0 \phi$，NLO 效应可以提供$\sim 20\%$到$\sim 40\%$的增强效果，以提高其 CP 平均分支比的领先阶（LO）PQCD 预测，因此在包含 NLO 效应后，PQCD 预测与测量值之间的符合程度得到了有效改善；(b) 对于这些测量的衰变，LO PQCD 预测中对$(f_L,f_\perp)$和$(\phi_{\|},\phi_{\bot})$的 NLO 修正通常数值较小，但弱 penguin 湮灭贡献在理解它们的衰变率、$f_L$和$f_\perp$的数据方面起着重要作用；(c) 上述提到的物理可观测量的 NLO PQCD 预测与测量结果以及 QCDF、SCET 和 FAT 方法的理论预测是一致的；(d) 对于其他考虑的$B_s^0 \to VV$衰变，它们的衰变率和其他物理可观测量的 NLO PQCD 预测也基本上与其他流行的理论方法的预测一致，未来的精确测量将有助于测试或检验这些预测。