【作者】 刘玉珂；

【导师】 李新强；

【作者基本信息】 河南师范大学 ， 理论物理， 2013， 硕士

【摘要】 粒子物理的标准模型是描述电弱相互作用和强相互作用的规范理论。在过去的几十年中，随着实验数据的不断积累，标准模型已被证明是迄今为止描述微观粒子相互作用规律的最完美的理论之一。然而，标准模型自身仍存在一些至今没有得到合理解决的问题，因而通常被认为是某一基本理论的低能有效理论。通常，我们可以通过扩展对称群或是增大费米子数目在更高的能标处创建新物理模型，同时这一理论应该能在现有的能标处过渡到标准模型。重味物理，特别是B物理，由于两家B介子工厂和其它与B介子相关的大型实验的推动，已经积累了丰富的数据供我们在这些实验中寻找新物理存在的信号。因此，B介子物理研究是目前国际粒子物理学界十分流行的重要研究领域之一。本文首先介绍了粒子物理标准模型的相关知识，Wilson系数的计算，以及QCD因子化方法下强子矩阵元的计算。然后，在一个具体的新物理模型——代非普适Z模型中，我们对B介子的几个辐射衰变过程进行了研究。在该模型中，由于非对角Z耦合的存在，会伴随有树图阶的味改变中性流，从而增加了八个中性的流-流算符；通过QCD修正，这些算符会对Wilson系数C7产生一定量的修正。考虑到这一效应，我们详细讨论了它们对B介子辐射衰变过程B X s,d和B V的可观测量，即衰变分支比，CP破坏和同位旋不对称性的影响。结合目前的实验结果，我们对这个模型的参数空间给出了限制。这些结果将会对将来的实验测量提供一些有意义的参考价值。更多还原

【Abstract】 The Standard Model of elementary particle is a gauge theory designed to describe the electroweak andthe strong interactions. During the past several decades, with the accumulation of more and moreexperimental data, it has been proved to be one of the most perfect theory used to describe the interactionlaw of microscopic particles. However, there are still some unsolved questions within the Standard Modelitself, which lead us to believe that it is just an effective theory of some more fundamental theory. Ingeneral, we could extend the gauge group and/or increase the fermion numbers to build New PhysicsModels. Heavy flavour physics, especially the B physics, can be used to probe the signal of New Physics,since now the two B factories and other experiments related to B mesons have accumulated a lot of precisedata. Thus, the study of B physics is one of the hot topics in current particle physics research.In this thesis, we first introduce the relevant basis of the Standard Model, the calculation of Wilsoncoefficients, as well as the hadronic matrix elements within the QCD factorization approach. Then, wemake a phenomenological study of several B-meson radiative decays in a specific New Physics model, i.e.,the family non-universal Z model. There exist flavour changing neutral currents generated bynon-diagonal Z-boson coupling, which will introduce eight neutral current-current operators. They couldgive some corrections to the Wilson coefficientC7due to QCD corrections, and hence affect theobservables of B-meson radiative decays, such as the branching ratios, the CP asymmetries and the Isospinasymmetries inB X s,d and B V. Combining the current experimental data, we can then putconstraints on the model parameters. These results will provide some useful guidelines for futureexperimental measurements.更多还原