Lattice QCD Studies of Baryon and Meson Excitations Using Spatially-extended Hadron and Multi-hadron Operators

量子色动力学（QCD）是目前公认的强核力理论，它将夸克和胶子结合在一起形成强子，如质子和中子。理解强子的形成是核/粒子物理中一个长期存在的问题。本提议的一个主要目标是使用在时空晶格上表述的QCD进行大规模计算机模拟，以从头开始确定QCD理论所期望的强子的质谱。所提出的活动的新颖之处在于使用大的空间扩展强子算子集来研究更大质量的激发态，而不仅仅是最轻的态。这些状态目前引起了实验学家的极大兴趣，例如托马斯·杰斐逊国家加速器设施的B厅n星计划和拟议中的D厅gluex实验计划，以及康奈尔大学的CLEO-c项目。理解强子内夸克约束的物理学也是一个重要的智力挑战；事实上，杨-米尔斯质量间隙是由马萨诸塞州剑桥克莱数学研究所宣布的七个所谓的千禧年奖问题之一。拟议的研究包括两名研究生，可能还有一名或多名本科生的参与，他们的教育不仅将通过参与核理论前沿的科学项目，而且还将通过利用最先进的并行计算资源的高技术培训得到加强。学生将被资助参加国际会议。拟议活动的广泛影响将通过在大众出版物上刊登文章和在公众可访问的网页上公布附有简化背景资料的结果来加强。

Quantum chromodynamics (QCD) is the currently accepted theory ofthe strong nuclear force which binds quarks and gluons together to formhadrons, such as the proton and neutron. Understanding hadron formationis a long standing problem in nuclear/particle physics. A major objectiveof this proposal is to use large-scale computer simulations with QCDformulated on a space-time lattice to carry out ab initio determinationsof the mass spectrum of hadrons expected from the QCD theory. The novelfeature of the proposed activities is the use of large sets of spatiallyextended hadron operators in order to study more-massive excited hadron states,not just the lightest states. These states are currently of great interest to experimentalists, exemplified by the Hall B N-star program and the GlueXexperimental program in the proposed Hall D at the Thomas Jefferson NationalAccelerator Facility, as well as the CLEO-c project at Cornell. Understandingthe physics of quark confinement within hadrons is also an important intellectual challenge; in fact, the Yang-Mills mass gap is one of the seven so-called Millenium Prize problems announced by the Clay Mathematics Institute of Cambridge, Massachusetts. The proposed research incorporates the participation of two graduate students, and possibly one or more undergraduate students, whose educations will be enhanced not onlyby involvement in scientific projects at the forefront of nuclear theory,but also with high-technology training in the use of state-of-the-artparallel computing resources. Students will be funded to participate ininternational conferences. The broader impacts of the proposed activitieswill be strengthened through articles in popular publications and by postingresults with simplified background information on publicly accessible web pages.