B介子遍举衰变中的幂次修正效应研究

正在运行的Belle-II和未来升级的HL-LHCb实验将会积累大量的B介子数据，从而对B介子的衰变过程给出更加精确的测量。为了精确检验标准模型以寻找新物理，B物理的理论计算也要提高到相应的精度。高精度计算除了需要考虑微扰圈图修正外，还需要考虑重夸克展开的幂次修正。我们将利用量子色动力学因子化方法和光锥求和规则方法，计算如下过程的幂次修正：(1) B介子遍举衰变B→γlν过程 (2) B→π/K形状因子 (3) B→D形状因子。研究将加强我们对B介子衰变振幅的因子化性质和端点发散问题的理解，同时精确可靠的数值结果可以帮助我们判定观测到的理论预言与实验测量的偏离导致的“B介子反常”是否为超越标准模型的新物理信号。

The running of the Belle-II super-B factory and the future High-Luminosity LHCb project will provide us with large amounts of experimental data and more precise measurement. To test the Standard Model and search for new physics, the precision of the theoretical calculation must be improved to match that of the data, which means that the sub-leading power correction from heavy quark expansion has to be considered besides the perturbative corrections. The major objective of this project is to calculate and estimate the leading power-suppressed effects in the following processes: (1) exclusive B-meson decay B→γlν, (2) B→π/K form factors and (3) B→D form factors in the framework of QCD factorization and light-cone sum rules. This will be essential to improve our understanding of the QCD factorization properties and end-point divergences. Meanwhile, high precision results will be crucial to distinguish whether the observed deviations between theoretical predictions and experimental measurements in B-meson decays, which are called “B anomalies”, are indeed due to new physics beyond the Standard Model.