Phenomenology of Hadrons and Fundamental Particles

强子和基本粒子现象学

• 批准号: 0140362
• 负责人: Richard Lebed
• 金额: $ 15万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-15 至 2006-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0140362&HistoricalAwards=false
• 关键词: Phenomenology; Hadrons; Fundamental; Particles

0140362LebedThree topics will be investigated under this grant, spanning both nuclear and particle theory.1) Flavor Symmetries. The PI and his graduate dissertation student (partially funded by this grant) will investigate possible "flavor" symmetries among the three fermion generations, especially the constraints imposed upon them by recent and forthcoming experimental results on neutrino masses and mixing. Additional constraints to be taken into account arise from limits on flavor-changing neutral current processes and proton decay. These studies are designed to work toward answering the question of why there are three replicated generations of fermions with nonetheless widely differing masses and mixings.2) Baryons in the Large N Limit. The PI will build upon the numerous successes of QCD with a large number N of color charges (large N) to study the dynamics of baryon resonances. These particles are now being produced in huge numbers at Jefferson Lab, but the theoretical tools currently used to study them are limited. In particular, the PI will seek model-independent results that respect not only the large N expansion, but also the chiral symmetry implied by coupling among pions and nucleons (to which the resonances decay).3) Rigorous QCD Constraints on Hadronic Quantities. The imposition of constraints from dispersion relations allows one to make precise statements about QCD amplitudes even in the nonperturbative regime. One obtains relations between fundamental quantities such as quark and gluon parameters on one hand, and measured quantities such as form factors on the other. These relations can provide subtle and highly nontrivial information on the way that the strong interaction works, and form the motivation for this work. The PI will continue this successful program to consider such cases as expanding the range of applicability and including additional information from the region of asymptotic freedom.

0140362列别德在此资助下将研究三个主题，涵盖核理论和粒子理论。 风味对称。 PI和他的研究生论文学生（部分由该基金资助）将研究三代费米子之间可能的“风味”对称性，特别是最近和即将到来的中微子质量和混合实验结果对它们的约束。 需要考虑的其他限制来自于对改变味道的中性电流过程和质子衰变的限制。 这些研究旨在回答为什么有三代重复的费米子，但质量和混合却有很大的不同。 大N极限中的重子 PI将建立在QCD的大量成功与大量的N色荷（大N）研究重子共振的动力学。 这些粒子现在正在杰斐逊实验室大量生产，但目前用于研究它们的理论工具有限。 特别是，PI将寻求与模型无关的结果，不仅要考虑大的N展开，还要考虑π介子和核子之间耦合所暗示的手征对称性（共振衰减）。 严格的QCD对强子对撞机的约束。 从色散关系的约束，即使在非微扰制度，使一个精确的陈述QCD振幅。 人们一方面得到夸克和胶子参数等基本量与另一方面得到形状因子等测量量之间的关系。 这些关系可以为强相互作用的工作方式提供微妙和高度重要的信息，并形成这项工作的动机。 主要研究者将继续这一成功的项目，以考虑扩大适用范围和纳入渐近自由区域的其他信息等情况。