Hadron Physics from Covariant QCD Modeling

这项提案要求三年的支持，以继续一项涉及一名高级研究员、一名博士后研究员和几名学生的研究计划。这项研究将结合最近在理解涉及胶子、鬼影和夸克场的传播子和顶点方面的进展，以及介子、形状因子和相互作用的协变建模的进展，从量子色动力学(QCD)的连续夸克和胶子的角度来研究强子和强子过程。主要研究人员在强子的连续非微扰QCD建模和随后基于该理论的Dyson-Schwinger方程的强子过程描述方面具有专业知识。以前的工作主要集中在求解修饰夸克传播子的Dyson-Schwinger方程，然后求解介子的边界态Bethe-Salpeter方程。已经出现的电子相互作用保持了QCD的微扰短距离行为，而微扰域是用两个参数描述的。它产生了动力学手征对称性破缺的经验量，并实现了与绝对夸克相关联的现象。对于轻夸克和重子的基态赝标量和矢量介子，这种方法的明显成功需要与其他人的最新进展相一致，这些进展增加了我们对QCD规范玻色子部门的理解。特别是，我们试图用QCD更基本规范玻色子部门的独立研究结果来取代上述e相互作用的两个参数。规范扇区Dyson-Schwinger方程有可用的模型解，至少对于我们希望连接到的胶子和幽灵装饰的传播子是这样。此外，对于这些量和重要的胶子夸克顶点，也有来自QCD晶格模拟的独立质量数据。因此，发展受QCD数据约束的强子过程连续介质模型的时机已经成熟。这些问题涉及夸克常数的起源和动力学手征对称性破缺。关于如何超越阶梯近似的信息是不可能的，并且将被使用.后果将根据强子观测数据进行评估。我们需要这些信息来促进我们对强子物理的理解，并了解QCD规范部分的物理相关的非微扰动力学。我们的联合方法将是对强子物理背后的主要夸克-胶子机制的连续谱庞加莱不变量研究的进展。这个项目中的几个活动具有更广泛的影响。用这笔赠款进行的研究有助于推动核物理和粒子物理的发展。强子性质和过程的夸克-胶子基础是核物理的一个焦点领域，理论进步对JLab和RHIC实验设施的投资回报做出了贡献。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生教学，促进研究和教育的整合。此外，学生还有机会参加专业会议。与德国图宾根大学的科学家的国际合作，需要实施该项目的一部分，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.