RUI: Hadronic Structure from Spin Observables in pQCD

原子核由质子和中子组成，质子和中子是更广泛的强子粒子类别的一部分。然而，这些强子不是物质的基本形式，因为它们是由其他粒子组成的，即夸克和胶子(统称为部分子)。这些部分粒子在强子内部形成了一个受强核力支配的动力系统。核物理研究的一个目标是通过这些部件的相互作用来了解这种内部结构，这些部件是可见物质的基本部件。特别是，对对强子和/或部分子的一种称为自旋的本征性质敏感的高能碰撞的分析特别有用。这些观测使我们能够探索强子内部部分子的三维运动，以及质子的自旋是如何从其组成的部分子中产生的。这项研究将使我们更好地洞察强子结构的这些方面，并为未来在美国建造的电子-离子对撞机提供科学支持。将把本科生纳入该项目的实质性部分，以培养年轻科学家对核物理子领域的兴趣，并为他们今后的研究生涯进行培训。这一研究项目将进一步加深我们对对部分子固有横向运动和关联敏感的可观测粒子的了解，这些关联允许在动量空间中对强子进行三维成像。这包括对对强子自旋敏感的各种实验的数据进行全局分析，以便使用迭代蒙特卡罗例程提取相关函数，对其内部结构进行编码。这些函数随后将用于预测相对论重离子对撞机(RHIC)、杰斐逊实验室的12 GeV升级(JLab-12)和未来的电子离子对撞机(EIC)即将进行的测量。由于需要一个严格的理论形式来解释这些实验数据，这个项目还将通过量子色动力学(QCD)中的高阶计算来巩固用于自旋可观测的框架。最后，该项目将通过分析质子自旋有多少是由只携带一小部分质子动量的部分子造成的，来研究质子自旋如何从其组成部分产生的某些方面。这项研究将纳入第一原理结果，作为提取可用于计算其在该地区的自旋的部分子函数的输入。该奖项反映了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。

The nucleus of an atom is made up of protons and neutrons, which are a part of a broader category of particles called hadrons. However, these hadrons are not a fundamental form of matter since they are composed of other particles, namely, quarks and gluons (collectively called partons). The partons form a dynamical system inside of hadrons that is governed by the strong nuclear force. A goal of nuclear physics research is to understand this internal structure through the interactions of these partons, the elementary pieces of visible matter. In particular, the analysis of high-energy collisions sensitive to an intrinsic property, called spin, of hadrons and/or partons is especially useful. These observables allow us to explore the 3-dimensional motion of partons inside of hadrons and how the proton's spin arises from its constituent partons. This research will give us better insight into these aspects of hadronic structure as well as support the science of the future Electron-Ion Collider to be built in the United States. Undergraduate students will be included in substantive parts of the project in order to foster the interests of young scientists in the subfield of nuclear physics and train them for future careers in research. This research project will further our knowledge of observables sensitive to parton intrinsic transverse motion and correlations, which allow for a 3-dimensional imaging of hadrons in momentum space. This includes performing a global analysis of data from various experiments sensitive to the spin of hadrons in order to extract the relevant functions, using an iterative Monte Carlo routine, that encode their internal structure. These functions will then be used to make predictions for upcoming measurements at the Relativistic Heavy Ion Collider (RHIC), Jefferson Lab's 12-GeV upgrade (JLab-12), and a future Electron-Ion Collider (EIC). Since a rigorous theoretical formalism is needed in order to interpret such experimental data, this project will also solidify the framework used in spin observables through higher-order calculations within quantum chromodynamics (QCD). The project will lastly investigate certain aspects of how the proton spin arises from its constituent partons by analyzing how much of this spin is due to partons that carry only a small fraction of the proton's momentum. The study will incorporate first principle results as input to the extraction of partonic functions that can be used to calculate their spin in this region.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.