Lattice Gauge Theory at the Intensity Frontier

强度前沿的格子规范理论

• 批准号: 1414614
• 负责人: Carleton DeTar
• 金额: $ 30万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1414614&HistoricalAwards=false
• 关键词: Lattice; Gauge; Theory; Intensity; Frontier

This award funds the research activities of Professor Carleton DeTar of the Department of Physics and Astronomy at the University of Utah. These activities are carried out in collaboration with scientists at several US universities and government laboratories. The research addresses fundamental questions in high energy and nuclear physics, and is directly related to major experimental programs in these fields. The principal goal of this research is to discover evidence for new fundamental physical processes and particles. This is done by comparing precise predictions of the presently agreed upon models with results of precise experiments. Secondary projects include a study of exotic states consisting of heavy quarks and a study of the properties of matter at extreme temperatures, such as may have occurred in the very early universe. The methods the PI will develop and the calculational products and software are used widely around the world for related studies. Algorithmic ideas developed in this project will almost certainly have applications in other computational fields. The supported activity promotes the development of young scientists.In more technical terms, Professor DeTar is carrying out a broad research program in Quantum Chromodynamics (QCD), the theory of interacting quarks and gluons, in which he has been engaged for a number of years. He does this using numerical calculations on high performance computers. These numerical calculations are done on a grid of space-time points (lattice). During the last several years he has generated a library of gluon configuration ensembles with up, down, strange and charm quarks, using the Highly Improved Staggered Quark (HISQ) action. They can be thought of as "snapshots" of the QCD vacuum. They are the basis for a wide variety of calculations of physical interest. These ensembles have significantly smaller lattice artifacts than those previously generated with the improved staggered (asqtad) action. Moreover, the PI has reached an important milestone by, for the first time, generating configurations in which the four lightest quarks are all included with masses at or very close to their physical values. For these reasons the HISQ ensembles are enabling major improvements in the calculation of a variety of physical quantities of importance in high energy physics. Under this project the PI will use them to extend studies of the leptonic decay constants of the pi, K, D, Ds, B and Bs mesons, the semileptonic form factors of D and B mesons, and the mixing of neutral B and Bs mesons with their antiparticles. These calculations will enable him to significantly improve the precision of the determinations of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements V_us, V_ub, V_cd, V_cs, and V_cb, as well as the masses of the up, down, strange, charm and bottom quarks. The calculations of the CKM matrix elements will enable more stringent tests of current theories of the fundamental interactions of physics, while the determination of related hadronic weak interaction matrix elements can shed light on theories that have been proposed to study physics that goes beyond our current theories. In addition, the PI will extend the study of QCD at high temperatures with the HISQ action that for the first time includes the effects of charm sea quarks. Finally, he will continue the effort to improve the precision of the determination of lattice spacings through use of the gradient flow.

该奖项资助了犹他州大学物理和天文学系Carleton DeTar教授的研究活动。这些活动是与美国几所大学和政府实验室的科学家合作开展的。该研究解决了高能和核物理中的基本问题，并与这些领域的主要实验计划直接相关。这项研究的主要目标是发现新的基本物理过程和粒子的证据。这是通过将目前商定的模型的精确预测与精确实验的结果进行比较来完成的。次级项目包括研究由重夸克组成的奇异状态，以及研究极端温度下物质的性质，例如可能发生在非常早期的宇宙中。PI将开发的方法以及计算产品和软件在世界各地广泛用于相关研究。在这个项目中开发的数学思想几乎肯定会在其他计算领域中得到应用。DeTar教授在量子色动力学（QCD）方面开展了广泛的研究计划，这是一个关于夸克和胶子相互作用的理论，他已经从事了多年。他在高性能计算机上使用数值计算来实现这一点。这些数值计算是在时空点的网格（格子）上完成的。在过去的几年里，他已经产生了一个库的胶子配置合奏与上，下，奇怪和魅力夸克，使用高度改进的交错夸克（HISQ）的行动。它们可以被认为是QCD真空的"快照"。它们是各种物理兴趣计算的基础。这些合奏有显着更小的晶格文物比以前产生的改进交错（asqtad）的行动。此外，PI已经达到了一个重要的里程碑，第一次产生了四个最轻的夸克都包含在质量等于或非常接近其物理值的配置。由于这些原因，HISQ系综使高能物理中各种重要物理量的计算得到重大改进。在该项目下，PI将利用它们来扩展对π、K、D、Ds、B和Bs介子的轻子衰变常数、D和B介子的半轻子形状因子以及中性B和Bs介子与其反粒子的混合的研究。这些计算将使他能够显著提高Cabibbo-Kobayashi-Maskawa（CKM）矩阵元素V_us、V_ub、V_cd、V_cs和V_cb以及上、下、奇、魅和底夸克质量的测定精度。CKM矩阵元的计算将使物理学基本相互作用的当前理论能够进行更严格的测试，而相关强子弱相互作用矩阵元的确定可以揭示已经提出来研究超越我们当前理论的物理学的理论。此外，PI还将利用HISQ作用量扩展高温下QCD的研究，该作用量首次包括了粲海夸克的影响。最后，他将继续努力，以提高精度的决定晶格间距通过使用梯度流。