Hard Scattering Processes in QCD

量子色动力学（QCD）是强相互作用的微观理论，使我们能够理解强子，如质子，中子和π介子，是如何形成的。反过来，核子（质子和中子）占宇宙可见物质质量的99%以上。核子由夸克和胶子（部分子）组成，它们是QCD的基本粒子。核子的结构是在美国和国外最先进的实验设备上用高能散射过程研究的。该项目将提供理论指导，并帮助分析在这些实验设施产生的实验数据。 此外，PI将指导研究生，并参与针对高中生，教师和本科生的外展活动。该项目将主要集中在强子物理学的两个主题上。 首先，将对双强子产生进行新的横向分布拟合，这通常被认为是一个非常干净的通道。 经过仔细的领导阶分析后，将在共线次领导（NLO）阶框架中提取横向性。 这就需要，特别是，有史以来第一次具有挑战性的非线性光学计算的相关双强子在电子-正电子湮灭，轻子-核子散射和质子-质子碰撞的可观测量。 这项研究有望揭示新的长期紧张局势之间的核子的横向信息，一方面从实验数据，另一方面从格子QCD。 该项目的第二部分涉及部分维格纳函数。 由于许多原因，部分子维格纳函数在过去几年中引起了极大的兴趣。 尽管它们很重要，但目前还没有关于这些物体的实验资料。 因此，主要的重点将放在维格纳函数的观测。 这包括观测量的数值估计，高阶修正的计算，以及寻找维格纳函数出现的新过程。 特别关注的是未来的电子-离子对撞机（EIC）如何进一步推动这一研究领域的问题。该奖项反映了NSF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。

Quantum Chromodynamics (QCD) is the microscopic theory of the strong interactions that allows us to understand how hadrons, such as the proton, neutron and pion, are formed. In turn, nucleons (protons and neutrons) make up more than 99% of the mass of the visible matter of the universe. Nucleons are composed of quarks and gluons (partons), the fundamental particles of QCD. The structure of the nucleon is studied using high-energy scattering processes at state-of-the-art experimental facilities in the USA and abroad. This project will provide theoretical guidance and help analyze experimental data generated at those experimental facilities. Furthermore, the PI will mentor graduate students and engage in outreach activities addressing high school students, teachers, and undergraduate students.The project will primarily concentrate on two topics in hadronic physics. First, a new fit of the transversity distribution will be performed for di-hadron production, which is generally considered a very clean channel. After a careful leading-order analysis, the transversity will be extracted in a collinear next-to-leading (NLO) order framework. This requires, in particular, the first-ever challenging NLO calculation of the relevant di-hadron observables in electron-positron annihilation, lepton-nucleon scattering and proton-proton collision. This study is expected to shed new light on the longstanding tension between information on the nucleon's transversity from experimental data on the one hand and from lattice QCD on the other. The second part of the project deals with partonic Wigner functions. For a number of reasons, partonic Wigner functions have attracted enormous interest over the last years. Despite their importance, presently no experimental information is available on these objects. The main focus will therefore be on observables for Wigner functions. This includes numerical estimates of observables, the calculation of higher-order corrections, and the search for new processes in which Wigner functions show up. Special attention will be paid to the question about how a future electron-ion collider (EIC) can further this research area.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.