CAREER:Nucleon Structure, Fundamental Symmetries, and Lattice QCD

质子和中子是所有可见物质的基本组成部分。它们是在大爆炸中与反质子和反中子一起产生的。尚不清楚为什么在早期宇宙中产生了比反粒子更多的粒子，正是这些粒子幸存下来，成为目前存在的所有核物质。只有当时间颠倒时，物理定律并不完全对称时，这种不平衡才可能发生。如果是这样的话，核实验必须观察到中子在电场中的进动(旋转)。在接下来的十年里，这类实验的精确度将提高100倍。这个项目的目的是提供理论基础，以检查实验是否符合已知的基本粒子相互作用，并测量物理定律的空间反射和时间反转对称性被破坏了多少。这些问题是现代核物理的核心，为了理解所有已知物质的起源，必须回答这些问题。核子(质子和中子)、原子核和原子的电偶极矩(EDM)可以由组成它们的基本粒子的时间反转(T)对称性破坏相互作用而产生。虽然标准模型包含T破坏，但破坏不足以产生观测到的宇宙重子不对称。这本身就指向了新的、但未知的粒子相互作用类型，如夸克的色电偶极矩、三胶子和四夸克有效相互作用。核子和原子核的EDM也可以由规范场的非平凡拓扑(所谓的θ项)产生，但到目前为止还没有观察到这种拓扑结构。虽然控制夸克和胶子的理论是已知的，但它在解析上是困难的，需要数值计算(晶格QCD)来计算核子结构和EDM，这是本项目的目标。因此，目前和未来测量EDM的实验都处于基础物理的前沿。然而，他们的解释关键取决于将在这个项目中执行的对核子结构的精确理论计算。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Protons and neutrons are the basic building blocks of all visible matter. They were created in the Big Bang together with antiprotons and antineutrons. It is unknown why more particles than antiparticles have been created in the early Universe, and it is the particles that have survived to become all of the presently existing nuclear matter. Such an imbalance may occur only if physical laws are not exactly symmetric when time is reversed. If this is the case, nuclear experiments must observe precession (rotation) of neutrons in an electric field. In the next decade the precision of such experiments will be improved 100-fold. This project is aimed at providing the theoretical foundations to examine whether experiments agree with known interactions of elementary particles or not, and measure how much the space reflection and time reversal symmetries of physical laws are broken. These questions are at the heart of modern nuclear physics and they have to be answered to understand the origin of all known matter.Electric dipole moments (EDMs) of nucleons (protons and neutrons), nuclei, and atoms can be induced by time reversal (T) symmetry-violating interactions of elementary particles that comprise them. While the standard model contains T violation, the violation is not sufficiently large to produce the observed baryon asymmetry of the Universe. This alone points to new, yet unknown types of particle interactions, such as color-electric dipole moments of quarks, three-gluon, and four-quark effective interactions. EDMs of nucleons and nuclei may also be produced by nontrivial topology of gauge fields (the so-called theta-term) that has not been observed so far. While the theory governing quarks and gluons is known, it is intractable analytically, and requires numerical calculations (lattice QCD) to compute nucleon structure and EDMs, which is the aim of this project. Current and future experiments measuring EDMs are thus at the frontier of fundamental physics. Their interpretation, however, depends critically on precise theoretical calculations of nucleon structure that will be performed in this project.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.