Three-Body Amplitudes from Lattice QCD

强大的力量是宇宙中已知物质形成的原因，但这一过程的详细机制仍然是一个谜。强作用力将原子核中的核子（质子和中子）结合在一起，核子的性质在最先进的加速器设施中进行研究，例如托马斯杰斐逊国家加速器设施。本项目旨在利用点阵量子cd缩小实验与理论计算之间的差距。由于目前经典计算机的局限性，晶格QCD计算是在一个小的立方体积中进行的，而不是在无限空间中进行的。本项目提供了从前者到后者的转换，以便QCD的基本计算可以与Nature进行比较。PI和他的学生将专注于涉及三个粒子相互作用的系统的性质。为了帮助培养多样化的，具有全球竞争力的STEM劳动力，外展组件致力于开发量子力学（QM）计算方面的材料和时间相关QM问题的动画。对于三个粒子的有限体积效应，人们知之甚少。在这个项目中，PI和他的学生将开发和应用三体方法将点阵QCD结果映射到物理世界，并帮助回答有关激发介子和重子性质的QCD预测的基本问题。为此，统一原理被有效地用作构造三个或更多粒子振幅的指导原则。先前工作的概念升级涉及引入更多耦合通道和扩展到半整数自旋。三体动力学不仅在理论上困难，而且在现象学方面也困难。因此，无限体积下的三体振幅将以互补的方式发展并与实验进行比较，如Roper共振及其多通道三体动力学，或A1（1260）轴向介子的各种衰变通道。计划对两个不同介子质量的GW群的新晶格QCD结果进行扩展分析，这将允许绘制A1（1260）轴向介子的手性轨迹。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Strong forces are responsible for the formation of known matter in the Universe, but the detailed mechanisms of how this happens remain a mystery. Strong forces bind nucleons (protons and neutrons) together in atomic nuclei, and the properties of the nucleons are studied at state-of-the-art accelerator facilities such as the Thomas Jefferson National Accelerator Facility. This project aims at closing the gap between experiment and theoretical calculations using lattice QCD. Due to current limitations of classical computers Lattice QCD calculations are performed in a small cubic volume instead of infinite space. This project provides the translation from the former to the latter, so that fundamental calculations of QCD can be compared to Nature. The PI and his students will focus on properties of systems involving three particles interacting with each other. To help develop a diverse, globally competitive STEM workforce, the outreach component is dedicated to developing material for computational aspects of quantum mechanics (QM) and animations of time-dependent QM problems. Finite-volume effects for the case of three particles are poorly understood. In this project, the PI and his students will develop and apply three-body methods to map lattice QCD results to the physical world and to help answer fundamental questions regarding QCD predictions for the properties of excited mesons and baryons. For this, the principle of unitarity is efficiently used as the guiding principle to construct three- or more particle amplitudes. A conceptual upgrade of previous work concerns the introduction of more coupled channels and extensions to half-integer spin. Three-body dynamics is not only difficult on the theory but also on the phenomenology side. Therefore, three-body amplitudes in infinite volume will be developed and compared to experiment in a complementary effort, such as the Roper resonance and its multi-channel three-body dynamics, or the various decay channels of the A1(1260) axial meson. An extended analysis of new lattice QCD results from the GW group at two different pion masses is planned, that will allow to map out the chiral trajectory of the A1(1260) axial meson.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.