Lattice Gauge Theory at the Intensity Frontier

该奖项资助犹他大学Carleton DeTar教授的研究活动。德塔尔教授的研究解决了高能和核物理中的基本问题，而且与这些领域的主要实验计划密切相关-实际上，甚至是必不可少的--。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。这是通过将对当前已知物理过程和粒子的理论的精确预测与精确实验的结果进行比较来实现的。德塔尔教授和他的合作者开发的方法以及他们的计算产品和软件在世界各地被广泛用于相关研究。除了保持美国在基础科学方面的卓越水平外，这项研究还支持美国在计算技术和人力方面的卓越地位。从事这些项目的学生和博士后研究助理将接受高性能计算和最先进的大数据集统计分析方面的极具市场价值的培训。用更专业的术语来说，德塔尔教授和他的合作者正在开展一项广泛的量子色动力学(QCD)研究计划，QCD是夸克和胶子相互作用的理论。他们通过在高性能计算机上进行数值计算来做到这一点。这些数值计算是在时空点(格子)的网格上进行的。在过去的几年里，他们利用高度改进的交错夸克(HISQ)作用，产生了一个胶子组态系综库，其中包括向上、向下、奇怪和迷人的夸克。这些胶子组态可以被认为是QCD真空的“快照”，是各种物理兴趣计算的基础。与之前使用改进的交错(Asqtad)动作生成的晶格伪影相比，这些集合的晶格伪影要小得多。此外，这些计算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其物理值或非常接近其物理值的质量中的配置。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了重大改进，包括对Muon磁矩的强相互作用贡献。这些标准模型预测的结果将与费米实验室目前正在进行的实验测量结果进行核对。德塔尔教授和他的合作者还在扩展他们对pi、K、D、DS、B和BS介子的轻子衰变常数，D和B介子的半轻子形式因子，以及中性B和BS介子与其反粒子的混合的研究。这些计算将使他们能够显著提高对Cabibbo-Kobayashi-Maskawa(CKM)矩阵元素V_us、V_Ub、V_cd、V_cs和V_Cb以及上夸克、下夸克、奇异夸克、魅力夸克和底夸克质量的测定精度。CKM矩阵元素的计算将为我们当前的物理基本相互作用理论提供更严格的测试，而相关强子弱相互作用矩阵元素的确定可以帮助约束已被提出的研究物理的理论，这些理论超出了我们当前的理论。

This award funds the research activities of Professor Carleton DeTar at the University of Utah. Professor deTar's research addresses fundamental questions in high-energy and nuclear physics, and is closely related --- indeed, even essential --- 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 theories of currently known physical processes and particles with the results of precise experiments. The methods that Professor deTar and his collaborators develop and their calculational products and software are used widely around the world for related studies. In addition to maintaining US excellence in fundamental science, this research supports US preeminence in computing technology and manpower. Students and postdoctoral research associates working on these projects receive highly marketable training in high-performance computing and state-of-the-art statistical analysis of large data sets. In more technical terms, Professor deTar and his collaborators are carrying out a broad research program in Quantum Chromodynamics (QCD), the theory of interacting quarks and gluons. They do 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 they have generated a library of gluon-configuration ensembles with up, down, strange and charm quarks, using the highly improved staggered quark (HISQ) action. These gluon configurations can be thought of as "snapshots" of the QCD vacuum, and are the basis for a wide variety of calculations of physical interest. These ensembles have significantly smaller lattice artifacts than those they previously generated with the improved staggered (asqtad) action. Moreover, these calculations have reached an important milestone by generating, for the first time, 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, including the strong-interaction contributions to the magnetic moment of the muon. Results of these Standard-Model predictions will be checked against experimental measurements currently underway at Fermilab. Professor deTar and his collaborators are also extending their 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 them to significantly improve the precision of their 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 provide more stringent tests of our current theories of the fundamental interactions of physics, while the determination of related hadronic weak-interaction matrix elements can help constrain theories that have been proposed to study physics that goes beyond our current theories.