b味强子弱衰变过程的新物理效应

发布时间：2018-04-16 00:03

本文选题：b-味强子 + 味改变中性流　；参考：《华中师范大学》2017年博士论文

【摘要】：粒子物理的标准模型是迄今为止描述电弱和强相互作用最成功的理论,并且也得到了实验上充分的检验。然而,它并不是完美无缺的理论,自身还存在着一些缺陷。并且它对一些过程的理论预言和实验结果还有着或大或小的差别。这都表明它并不是一个完整的理论,它应该是在某一能标下的低能有效理论,在更高的能标下应该有更基本的理论。重味物理的研究,不仅能够揭示近距离时的强相互作用物理,而且也是检验标准模型、研究CP破坏起源、稀有衰变和味改变过程的良好场所,还可以用来寻找新物理存在的证据。因此,重味物理是粒子物理最活跃的前沿领域之一。本文在一些新物理模型下,对b味强子(主要是∧b重子和Bs介子)的半轻衰变过程进行研究。首先,我们介绍了标准模型、CKM矩阵和幺正三角形、重整化、重整化群方程、算符乘积展开、低能有效哈密顿以及威尔逊系数计算等基础知识。接着,我们介绍了强子矩阵元的两种主要计算方法,QCD求和规则和格点QCD。之后是论文的主体部分,包括如下两个方面的内容:在矢量leptoquark模型、标量leptoquark模型、G(221)模型和双Higgs二重态模型Ⅲ等四个新物理模型下,我们对重子半轻衰变过程∧b→∧l+l-的一些物理量像微分分支比dq2/dBR、双轻子系统的纵向极化FL、轻子侧的前后不对称AμFB、重子侧的前后不对称AFB∧以及双轻子极化不对称等物理量进行了研究。在研究过程中,对于重子∧b到∧的跃迁形状因子,在小q2的区域和大q2区域,我们分别采用QCD求和规则和格点QCD的形状因子来进行计算。根据这四个模型对各个物理量的影响,我们发现:对于该过程的微分分支比dq2/dBR,在2q24GeV2/c4、4q26GeV2/c4、6q28GeV2/c4、16q218GeV2/c4和18q220GeV2/c4范围内,当前的实验数据在标准模型框架内难以得到解释。当考虑这些新物理模型的贡献,对于在2g24GeV2/c4和6q28GeV2/c4范围内的实验数据,矢量leptoquark模型和G(221)模型能够进行解释。对于16q218GeV2/c4和18q220GeV2/c4范围内的实验数据,双Higgs二重态模型能够进行解释。对于该过程轻子侧的前后不对称AFBμ,在15q216GeV2/c4、16q218GeV2/c4和18q220GeV2/c4范围内,它的实验数据在标准模型框架内不能得到解释。当考虑这些新物理模型的贡献,对于15g216GeV2/c4范围内的实验数据,标量leptoquark X(3,2,7/6)和双Higgs二重态模型能够进行解释。对于该过程轻子侧的前后不对称AFB∧,它只对标量leptoquark X(3,2,1/6)的贡献是敏感的。对于该过程的双轻子极化不对称PLN,PNL,PNT和PTN,它们标准模型的理论预言值都非常小,对这四个新物理模型的贡献也都不敏感,其余PLT、PNN和PTT对这第四个新物理模型的贡献是敏感的。同样,在这四个新物理模型下,我们也对B介子半轻衰变过程Bs→Φμ+μ-的一些物理量,像微分分支比dBR/dq2、双轻子系统的纵向极化FL和CP平均角分布系数S3、S4以及双轻子极化不对称进行了研究。在研究过程中,我们主要在小g2的区域进行讨论,对于Bs→Φ的跃迁形状因子,我们采用QCD求和规则的形状因子来进行计算。我们发现:对于该过程的微分分支比dBR/dq2,在2q25GeV2/c4和5q28GeV2/c4区域内,当前的实验数据在标准模型框架内难以得到解释,但能够在矢量leptoquark模型和G(221)模型中得到解释。对于该过程的双轻子系统纵向极化FL和CP平均角分布系数S3、S4,它们对这四个新物理模型的贡献都不敏感。对于该过程的双轻子极化不对称参数,仅仅PNN和PTT对这四个新物理模型的贡献是敏感的。随着LHC的进一步运行和未来将要运行的Super-b,更多的衰变道将被打开,这将为我们提供了更多的机会去了解和研究重味强子物理,尽管还面临很多问题,但它的研究是有价值的,也是有意义的。
[Abstract]:The standard model of particle physics is described thus far weak and strong interaction of the most successful theory, and has been tested experimentally fully. However, it is not the pink of perfection theory itself has some defects. And it is the theoretical predictions and experimental results of some process there are large or small this shows that difference. It is not a complete theory, it should be in a low energy effective theory under the standard, at a higher scale should have more basic theory. Research on heavy flavor physics, not only can reveal the strong interaction of near distance, but also the inspection standard study on the CP damage model, the origin, a good place to change the rare decay and taste, but also can be used to find the evidence of new physics. Therefore, heavy flavor physics is one of the most active fields of particle physics. In this paper, some new physics Model, the B (mainly a B taste of hadronic Bs meson and baryon) of semileptonic decay process. Firstly, we introduce the standard model, CKM matrix and unitary triangle, renormalization, renormalization group equation, operator product expansion, the basic knowledge of low-energy effective Hamiltonian and Wilson coefficient calculation. Then, we introduced two main method to calculate the hadronic matrix element, QCD sum rules and lattice QCD. is the main part of the thesis, including the following two aspects: the vector leptoquark model, scalar leptoquark model, G (221) model and the two Higgs doublet model III four new physical model next, some physical quantities of our baryon semileptonic decay process of a B, a l+l- like differential branch ratio dq2/dBR, FL dileptonic longitudinal polarization system, lepton side asymmetric A before and after FB, before and after the wrong AFB baryon side a and dileptons pole Asymmetry of physical quantities are studied. In the course of the study, for a B to the baryon transition shape factor A, in the little 2 area and a large area of Q2, we are using the QCD shape factor sum rules and lattice QCD are calculated. According to the effects of the four models of various physical quantities we find that the differential branch of the ratio of dq2/dBR, 2q24GeV2/c4,4q26GeV2/c4,6q28GeV2/c4,16q218GeV2/c4 and 18q220GeV2/c4 in the range of experimental data, it is difficult to be interpreted in the standard model framework. When considering these new physical model contribution for the experimental data in 2g24GeV2/c4 and 6q28GeV2/c4 within the scope of the vector leptoquark model and G (221) model explained. For the experimental data of 16q218GeV2/c4 and 18q220GeV2/c4 within the scope of the two Higgs doublet model can explain the process. For the lepton side before and after Symmetric AFB, 15q216GeV2/c4,16q218GeV2/c4 and 18q220GeV2/c4 in the range of experimental data, it cannot be explained in the framework of the standard model. When considering these new physical model for the contribution of the experimental data in the range of 15g216GeV2/c4 leptoquark X (3,2,7/6), scalar and two Higgs doublet model was explained. The process of lepton side before and after it is only on the asymmetric AFB a scalar leptoquark X (3,2,1/6) contribution is sensitive. For PLN, the process of double lepton polarization asymmetry of PNL, PNT and PTN, their standard model predicted values are very small, on the four new physical model of the contribution is not sensitive, the rest of the PLT, PNN and the contribution of PTT to the fourth new physical model is sensitive. Similarly, in the four new physical model, we also B semileptonic decay process of Bs, Phi Mu + mu - some physical quantities, such as differential branching ratio DBR/dq2, the angular distribution coefficient of S3 longitudinally polarized FL and CP average dileptons system, S4 and double lepton polarization asymmetry was studied. During the study, we mainly discussed in the small region of G2 for Bs, Phi transition form factor, shape factor, we adopt the QCD sum rules to calculate. We found that the differential branch of the ratio of dBR/dq2, 2q25GeV2/c4 and 5q28GeV2/c4 in the region, the current experimental data are difficult to explain in the standard model framework, but in the vector leptoquark model and G (221) explained the model. In the process of dileptons longitudinal polarization FL and CP average angular distribution coefficient S3, S4, their contribution to the four new physical models are not sensitive. The double lepton polarization asymmetry parameters of the process, PNN and PTT only contribution to the four new physical model is sensitive with LHC. The further operation and future will run the Super-b channel will be more open, which will provide us with more opportunities to understand and study the heavy hadron physics, while also facing many problems, but it is valuable research, but also meaningful.

【学位授予单位】：华中师范大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O572.2

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