Resonant Few-Body Systems from the Lattice

正如我们所知，强力是物质形成的原因，但这一过程的确切机制仍然是个谜。强作用力将原子核中的核子结合在一起，但它们也会导致更高能量的共振现象的出现，例如在托马斯杰斐逊国家加速器设施（JLab）进行的研究。对共振的实验和理论探索，以理解强作用力集中在少体系统和他们的动力学。该项目旨在缩小被称为点阵QCD的少体系统的理论计算与现象学之间的差距。该提案解决的主要技术挑战涉及这些计算是在一个小的立方体积中执行的问题，而不是无限的空间，以及如何去除相应的工件，使晶格QCD可以与自然相比较。这些预测与测量的偏差是新物理学的线索。该项目还旨在从概念上改进实验中三体数据的分析。PI将同时开发简单量子力学系统的模拟，以说明本科和研究生课程的标准教科书，以帮助培养多样化的，具有全球竞争力的STEM劳动力。强力背后的理论，量子色动力学（QCD），可以用点阵量子色动力学（QCD）来计算。然而，对于三个粒子的有限体积效应，人们知之甚少。该项目旨在进一步发展三体方法，使点阵QCD结果能够外推到物理世界，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，与核反应中概率守恒有关的统一性原理可以有效地用作指导原则，并且可以扩展到三个或更多粒子的扇区。在这个项目中，方法将在概念上进行升级，以应用于象征性共鸣。为了强调一点，由于其异常轻的质量以及其作为核子或强子分子的径向激发的争议性质，几十年来一直在研究罗珀共振。此外，在从头算晶格QCD计算中没有明确的信号。这个项目的重点是量化有限体积效应来解决这个难题。其他的研究方向是轴向共振，在它们的三体动力学中，类似于假想的奇异介子——一种在JLab和其他实验中寻找的新型粒子。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 matter as we know it, but the precise mechanism of how this occurs remain a mystery. Strong forces bind nucleons together in atomic nuclei, but they also lead to the emergence of resonant phenomena at higher energies that are studied, e.g., at the Thomas Jefferson National Accelerator Facility (JLab). The experimental and theoretical quest for resonances to understand the strong force focuses on few-body systems and their dynamics. This project aims at closing the gap between theoretical calculations on few-body systems, called lattice QCD, and phenomenology. The main technical challenge addressed in this proposal concerns the problem that these calculations are performed in a small cubic volume instead of infinite space, and how to remove the corresponding artifacts so that lattice QCD can be compared to Nature. Deviations of these predictions from measurements are hints for new physics. The project also aims to conceptually improve the analysis of three-body data from experiment. The PI will in parallel develop simulations of simple quantum mechanical systems to illustrate the undergraduate and graduate curriculum along the lines of standard textbooks to help develop a diverse, globally competitive STEM workforce.The theory underlying the strong force, Quantum Chromodynamics (QCD), can be calculated using Lattice QCD. However, finite-volume effects for the case of three particles are poorly understood. This project aims to further develop three-body methods to enable the extrapolation of 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, related to the conservation of probability in nuclear reactions, can be efficiently used as the guiding principle, and can be extended to the three- or more particle sector. In this project, methods will be conceptually upgraded to be applied to emblematic resonances. To highlight one, the Roper resonance has been under investigation for decades due to its unusually light mass and its debated nature as radial excitation of the nucleon or hadronic molecule. Furthermore, there is no clear signal for it in ab-initio lattice QCD calculations. The focus of this project is to quantify the finite-volume effects to solve this puzzle. Other lines of investigation address axial resonances that, in their three-body dynamics, resemble the supposed exotic mesons – a new type of particle sought for at JLab and other experiments.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.