重味强子衰变和新物理在LHCb的检测可能性的探讨

1) anti-triplet b-baryon decays.a. charmless decay modes: We have studied Λb→p(K(*)-,π-,rho-) decays, where the large CP violating asymmetry of Λb→pK(*-) predicted to be 20% triggered the experimental measurement. To search for other valuable CP and T violating asymmetries, which can be accessible to the experiments, the systematic study of all charmless b-baryon decays is necessary. We also note that the measured Λb→Λη(') decays that seem not to support the previous study need a new theoretical analysis...b. semileptonic decay modes: The observation of B(Λb→pe υ_e) indicates the possible observations of the counterparts of Λb→Λllbar and Λb→Λυ υbar decays, which are sensitive to new physics. Hence, the theoretical predictions are necessary, to be compared to future measurements...c. purely baryonic b-baryon decays: While the purely baryonic b-baryon decays may have final states of proton and neutron as the gradients of the ordinary matter, the CP violating asymmetry that is directly related to the matter-antimatter asymmetry can be important topic. We will hence study the simplest case of Λb→ppbarn, and other purely baryonic decays, in order to search for possible CP and T violating effects...2) Baryonic B decays.a. charmful and charmless decay modes: Since LHCb are able to measure Bs decays, the theoretical studies of Bs→pΛbarD0 and Bs→pΛbar(K-,π-) are apparently needed, which are the counterparts of B0→ppbarD0 and B→ppbar(K,π), respectively, observed in the B factories. ..b. semileptonic decay modes: Since LHCb are able to measure Bs decays, the semileptonic Bs decays of Bs→pΛbar e ν_e, ΛΛbar llbar, andΛΛυυbar require the theoretical predictions to be compared to the future experiments...c. Vub extraction: B-→ppbar e ν_e can also be used to constrain |Vub|; moreover, to test new physics from the right-handed currents not given in the Standard Model...3) Discrete CP and T violations: With the final states to be spin-1/2 baryons, there can be rich T-odd observables. Therefore, apart from the CP violating asymmetry, one can also study the T violating asymmetry.

1）b-重子衰变：.a. 无魅夸克之稀有衰变：全面计算如 Λb→p(K(*)-,π-,rho-) 的稀有衰变和电荷宇称破坏。.b. 准轻子型衰变对新物理非常灵敏。我们将会建立理论方法，进而利用角分布等物理量有效限制新物理。.c. 纯重子性b-重子衰变的计算：以Λb→ppbarn 而言，它的最终粒子是构成物质的质子和中子，其电荷宇称破坏是与物质－反物质不对称的问题直接相关。.2）重子性 Bs 介子衰变：.既然LHCb 有能力对 Bs→pΛbarD0，pΛbar(K-,π-)作测量，我们会先给出理论上的结果。并且，准轻子型衰变如 Bs→pΛbar e νe 可限制右手型手征流对于新物理的贡献。.3）时间反演破坏：以上拥有自旋1/2 的重子的衰变，能产生丰富的T-odd物理量。

背景：BELLE与LHCb 研究 B 介子衰变。同时，LHCb 拥有更多的Bs 介子事例，也能研究底夸克(b)-重子衰变。而 BESIII 能进行Lambda_c重子、D介子衰变实验研究。上述国际合作组所产出的实验值需要理论解释，并且需要理论预言。.主要研究内容：对于重子型B 介子衰变，b-重子衰变，粲重子与 D介子衰变，我们建立或发现适用的理论方法，如：因子化方法，SU(3) 味对称性的不可约化表示，夸克拓扑图，光前夸克模型，W玻色子湮灭、交换的衰变机制，或末态重散射机制。我们也讨论CP 破缺，四夸克态、五夸克态及标量介子的产生。我们「具体」的列出可能的衰变通道，与相关的可观测量，为其提供理论计算。我们完成了下列的研究：1. 含粲的二体重子型B介子衰变，2. 三体与四体重子型B (Bs) 介子衰变与 Bc介子衰变，3. 二体与三体粲重子衰变，4. Omega_c-->Omega\pi, Omega\pi\rho, Omega e\nu_e衰变，5. 多重味重子衰变，6. 纯重子型、无粲，及半轻b-重子衰变，7. a0(980) 标量介子的产生，8. CKM 矩阵元 Vub, Vcb的抽取，用以限制新物理。.重要结果、关键数据及其科学意义：1. 我们首度解释四体重子型 B 介子衰变，预言大于10% 的CP 破缺，帮助理解标准模型中的CKM 矩阵。2. 我们计算\bar B^0-->\Lambda_c\bar p 分支比，指出在湮灭机制下，因子化贡献未必压低，与先前的理论文献有明显不同。我们预言相关衰变分支比，而这一系列衰变通道的实验已经超过十年没有更新与进展。3. 利用 Omega_c-->Omega 形状因子，我们预言Omega_c-->Omega\pi, Omega\pi\rho, Omega e\nu_e衰变的分支比，帮助理解粲重子衰变中的强子化效应。4. 粲重子衰变有明显的非因子化贡献，造成计算的困难。我们利用SU(3) 味对称性的不可约化表示提供可靠的理论预言。我们也利用夸克拓扑图，把粲重子衰变表达成方便理解的图像。5. Ds-->\pi a0(980) 被认为是出自于W玻色子的湮灭机制。而我们指出: 湮灭机制会破坏G-宇称守恒，而末态重散射机制能解释实验分支比。我们也预言 Lambda_c-->Lambda a0(980)的分支比，能被实验测量。