Hadron Physics from Covariant QCD Modeling

项目概述：本项目申请三年资助，由一名高级研究员、一名博士后和几名学生组成。本研究将从量子色动力学（QCD）的共轭夸克和胶子的角度出发，通过结合对涉及胶子、鬼影和夸克的传播子和顶点的最新研究进展来解决强子和强子过程。在介子、形状因子和相互作用的协变建模方面取得进展。首席研究员在强子的连续体非微扰QCD建模和基于理论的Dyson-Schwingerequations的强子过程的后续描述方面具有专业知识。先前的工作主要集中在解决穿著夸克传播子的Dyson-Schwinger方程，然后是解决介子的边界态Bethe-Salpeter方程。出现的有效相互作用保留了QCD的微扰短距离行为，而微扰域用两个参数描述。它产生了动态手性对称破缺的经验量，并实现了与之密切相关的绝对夸克共轭现象。这种方法对于轻夸克的基态伪标量和矢量介子以及重子的明显成功，需要与最近其他人的进展相协调，这些进展增加了我们对QCD的规范玻色子部分的理解。特别是，我们寻求用QCD中更基本的规范玻色子扇区的独立研究结果来取代上述有效相互作用的两个参数。至少对于我们希望连接的胶子和鬼衣传播子，规范扇形戴森-施温格方程有可用的模型解。此外，对于这些量和重要的gluonquarkvertex，从QCD的晶格模拟中也可以获得独立的质量数据。因此，发展受QCD数据约束的强子过程连续统模型的时机已经成熟。这些问题涉及到夸克凝聚的起源和动态手性对称性破缺。关于如何超越阶梯近似的信息是现成的，并将被使用。后果将根据强子可观测值进行评估。这一信息既可以促进我们对强子物理的理解，也可以了解QCD规范扇区的物理相关的非微扰动力学。我们的联合方法将是强子物理中主导夸克-胶子机制的连续统庞加莱不变量研究的一个进步。本项目中的若干活动具有更广泛的影响。用这笔拨款进行的研究有助于推进核物理和粒子物理。强子性质和过程的夸克-胶子基础是核物理学的一个重点领域，理论进展有助于JLab和RHIC实验设施的投资回报。这项工作还通过培养研究生和博士后学者，以及通过研究生和博士后学者参与本科教学，有助于研究和教育的整合。学生也有机会参加专业会议。与德国图宾根大学（University of Tuebingen）科学家的国际合作，需要执行该项目的一部分，为国家的研究和教育基础设施做出贡献。

Project SummaryThis proposal requests three yeas of support to continue a research program involving one seniorinvestigator, one postdoctoral fellow and several students. The research will address hadronsand hadronic processes in terms of the con.ned quarks and gluons of Quantum Chromodynamics(QCD)b y joining recent advances in understanding the propagators and vertices involvinggluon, ghost and quark .elds with advances in covariant modeling of mesons, form factors andinteractions.The principal investigator has expertise in continuum nonperturbative QCD modeling ofhadrons and the subsequent description of hadronic processes based on the Dyson-Schwingerequations of the theory. Previous work has concentrated upon the solution of the Dyson-Schwinger equation for the dressed quark propagator followed by the solution of the boundstate Bethe-Salpeter equation for mesons. The e.ective interaction that has emerged preservesthe perturbative short distance behavior of QCD while the perturbative domain is describedwith two parameters. It generates the empirical amount of dynamical chiral symmetry breakingand the closely related phenomena of absolute quark con.nement is implemented. The evidentsuccess of this approach for the ground state pseudoscalar and vector mesons of light quarks,and for baryons, needs to be reconciled with recent advances by others that have increased ourunderstanding of the gauge boson sector of QCD.In particular, we seek to replace the two parameters of the above-mentioned e.ective interactionby results of independent studies of the more fundamental gauge boson sector of QCD. Thereare available model solutions of the gauge sector Dyson-Schwinger equations for at least the gluonand ghost dressed propagators that we wish to connect to. Also there is available independentquality data from lattice simulations of QCD for these quantities and for the important gluonquarkvertex. Thus the time is ripe for development of continuum models of hadronic processesconstrained by QCD data. These issues relate to the origin of quark con.nement and dynamicalchiral symmetry breaking. Information on how to move beyond the ladder approximation is athand and will be used. The consequences will be subjected to an evaluation in terms of hadronicobservables. This information is needed to both advance our understanding of hadron physicsand learn about the physically relevant nonperturbative dynamics of the gauge sector of QCD.Our combined approach will be an advance in continuum Poincare invariant investigations of thedominant quark-gluon mechanisms underlying hadron physics.Several activities within this project have broader impact. The research undertaken withthis grant helps to advance both nuclear and particle physics. The quark-gluon basis of hadronicproperties and processes is a focus area of nuclear physics and theoretical progress contributesto the return on the investment in the experimental facilities at JLab and RHIC. This work alsocontributes to the integration of research and education through the training of graduate studentsand postdoctoral scholars, and through the involvement of graduate students and postdoctoralscholars in undergraduate teaching. Also students get the opportunity to participate in professionalmeetings. The international collaborations with scientists at the University of Tuebingen,Germany, needed to carry out parts of this project contribute to the nation's infrastructure forresearch and education.