Higher Order Corrections to Nonleptonic and Rare Decays

对非轻子和稀有衰变的高阶修正

• 批准号: 230800025
• 负责人: Privatdozent Dr. Tobias Huber
• 金额: --
• 依托单位: Arbeitsgruppe Theoretische Physik 1 (Elementarteilchenphysik)
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/230800025?language=en
• 关键词: Higher; Order; Corrections; Nonleptonic; Rare

Nonleptonic exclusive decays of heavy mesons play a decisive role in quantifying the amount of CP violation, the most subtle phenomenon of flavour physics. In order to be competitive with precise measurements from current and future collider facilities, precision predictions from the theory side are indispensable for our understanding of the quark sector of the Standard Model (SM) and potentially even for finding hints for new physics. The aim of this project is to combine effective theory methods with the analysis of decay topologies and flavor symmetry relations and to increase the precision of the predicted amplitudes of two and three-body nonleptonic decays of bottomed (B) and charmed (D) mesons. For the two-body decays the emphasis is on achieving a quantitatively new level of accuracy. To this end we follow two approaches. On the one hand corrections to factorization theorems will be calculated in the effective theory framework, notably QCD factorization elaborated within Soft-Collinear Effective Theory. Besides higher-order perturbative (multi-loop) corrections, we will focus on contributions that are power-suppressed with respect to the inverse of the heavy quark mass. On the other hand we will make use of flavour symmetries and their breaking. By means of group-theoretical parameterizations of flavor symmetries we will derive amplitude relations which will be used for a model-independent description of the observables in these decays. One of the major goals is to quantify the final-state rescattering phases in two-body nonleptonic B-decays. Three-body decays offer ideal opportunities to search for CP violation in differential distributions. Therefore, the main effort will be aimed at phenomenological models for the Dalitz-distributions of the final states. Besides the more formal aspects such as the validity of factorization theorems at higher orders of the perturbative expansion, we will also perform dedicated phenomenological analyses which update and improve the theory predictions for nonleptonic B- and D-decays into light – in the case of B-mesons also into heavy – final states. In doing so, we will use updated and improved input parameters as well as reliable estimates for the universal hadronic matrix elements, derived from nonperturbative methods such as QCD sum rules and light-cone sum rules. Compared to nonleptonic B-decays, D-decays provide an important complementary test of CP violation within the SM. Since the mass of the charm quark is smaller than the mass of the bottom quark, and hence is further away from the heavy-mass limit, the theoretical description of D-meson decays is expected to be shaped by enhanced power corrections, which have to be carefully investigated and quantified.

重介子的非轻子排他衰变在确定CP破坏量方面起着决定性的作用，CP破坏是味物理中最微妙的现象。为了与当前和未来对撞机设施的精确测量竞争，理论方面的精确预测对于我们理解标准模型（SM）的夸克部分，甚至可能找到新物理学的线索是不可或缺的。本项目的目标是将联合收割机有效的理论方法与衰变拓扑和味对称关系的分析相结合，提高底（B）和粲（D）介子的二体和三体非轻子衰变振幅的预测精度。对于二体衰变，重点是在数量上达到新的精度水平。为此，我们采取两种方法。一方面，因式分解定理的修正将在有效理论框架中计算，特别是软共线有效理论中阐述的QCD因式分解。除了高阶微扰（多环）修正之外，我们将重点关注相对于重夸克质量的倒数被幂抑制的贡献。另一方面，我们将利用味对称性及其破缺。借助于味对称性的群论参数化，我们将导出振幅关系，该关系将用于这些衰变中的观测量的模型无关描述。主要目标之一是量化两体非轻子B衰变的末态再散射相。三体衰变为寻找微分分布中的CP破坏提供了理想的机会。因此，主要的努力将针对现象学模型的达利茨分布的最终状态。 除了更正式的方面，如因子分解定理的有效性在高阶微扰膨胀，我们还将进行专门的唯象分析，更新和改进的理论预测非轻子B-和D-衰变到轻-在B介子的情况下，也到重-最终状态。在这样做的时候，我们将使用更新和改进的输入参数以及可靠的估计的普遍强子矩阵元，来自非微扰的方法，如QCD求和规则和光锥求和规则。 与非轻子B衰变相比，D衰变提供了SM内CP破坏的重要补充测试。由于粲夸克的质量小于底夸克的质量，因此更远离重质量极限，D介子衰变的理论描述预计将通过增强的功率修正来塑造，这必须仔细研究和量化。