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arXiv 1407.8526hep-phhep-ex
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关于B-> K * mu + mu-观测量预测中幂修正的影响

On the impact of power corrections in the prediction of B->K*mu+mu- observables

Sébastien Descotes-Genon, Lars Hofer, Joaquim Matias, Javier Virto

摘要:

最近对排他性衰变B-> K ^* mu + mu-的LHCb角分析表明,与标准模型的预期有很大的偏差。对于一组优化的观测量,在α_s的首阶重夸克极限下对强子输入不敏感,可以在大的K~*介子反冲下得到精确的预言。然而,强子不确定性通过非微扰的Lambda_QCD/m_b功率修正重新出现,这必须被精确地评估。在QCD因式分解的框架内,我们提出了一个系统的方法,包括因式功率校正,并指出,它们对角可观测量的影响取决于选择的方案来定义软形状因子。与文献中早期的说法相反,相关的不确定性已得到控制。我们还讨论了可能的非因子分解功率校正的影响,包括估计的魅力循环效应。我们提供了两套不同的形状因子的输入,在大反冲角可观的结果,阐明了不同的理论不确定性的来源。最后,我们评论了最近的建议,解释异常的B-> K * mu + mu-观测通过魅力共振效应,我们提出了策略来测试这个建议,确定观测和运动学区域的魅力环模型可以从新物理效应或两个选项留下不同的印记。

英文摘要:

The recent LHCb angular analysis of the exclusive decay B->K^*mu+mu- has indicated significant deviations from the Standard Model expectations. Accurate predictions can be achieved at large K*-meson recoil for an optimised set of observables designed to have no sensitivity to hadronic input in the heavy-quark limit at leading order in alpha_s. However, hadronic uncertainties reappear through non-perturbative Lambda_QCD/m_b power corrections, which must be assessed precisely. In the framework of QCD factorisation we present a systematic method to include factorisable power corrections and point out that their impact on angular observables depends on the scheme chosen to define the soft form factors. Associated uncertainties are found to be under control, contrary to earlier claims in the literature. We also discuss the impact of possible non-factorisable power corrections, including an estimate of charm-loop effects. We provide results for angular observables at large recoil for two different sets of inputs for the form factors, spelling out the different sources of theoretical uncertainties. Finally, we comment on a recent proposal to explain the anomaly in B->K*mu+mu- observables through charm-resonance effects, and we propose strategies to test this proposal identifying observables and kinematic regions where either the charm-loop model can be disentangled from New Physics effects or the two options leave different imprints.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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