Using Muons and Protons to Probe the Structure of the Universe

使用 μ 子和质子探测宇宙结构

• 批准号: 2110293
• 负责人: Renee Fatemi
• 金额: $ 63.41万
• 依托单位: University of Kentucky Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2110293&HistoricalAwards=false
• 关键词: Using; Muons; Protons; Probe; Structure

This award supports two separate experimental programs, each aimed at exploring the structure of our universe at the most fundamental level. One program will investigate how the quarks and gluons that are produced in high energy proton-proton collisions spawn new quarks and gluons and eventually combine to form the particles that make up the visible universe. These studies will shed light on the nature of Quantum Chromodynamics, a theory that describes the strong force, one of the three fundamental forces that comprise the Standard Model of Particle Physics. The other program aims to discover signals of new forces and particles that are not yet included in the Standard Model. The g-2 experiment at Fermi National Laboratory aims to precisely measure the magnetic properties of the muon, a fundamental particle with characteristics very similar to the electron, but with 200 times the mass. This experiment is a second generation of an earlier measurement made at Brookhaven National Lab nearly twenty years ago that differs somewhat from the Standard Model theoretical calculations. The first result from the Fermilab measurement has been announced and it agrees with the earlier measurement but with better precision. The discrepancy between the experiments and the Standard Model points to possible contributions to the muon's magnetic moment from Beyond the Standard Model forces and/or particles. The Fermilab g-2 collaboration is in the process of analyzing and collecting additional datasets with the goal of further reducing the uncertainties on the measurement and pushing towards a discovery level discrepancy with the Standard Model predictions. The experiments supported by this grant will provide undergraduate and graduate students with the necessary tools and experience to either continue their work in basic research or to enter the technical workforce and lend their problem-solving expertise to a myriad of fields, including finance, big data analysis, patent law and medical physics. Undergraduate students funded by this award will continue to have the rare opportunity to experience the scientific culture and basic research performed at U.S. National Laboratories.This award will support the PI and two graduate students in using high energy pp and pA collisions at the Relativistic Heavy Ion Collider to extract longitudinal and transverse momentum dependent jet fragmentation functions from distributions of identified pions, kaons and protons inside of fully reconstructed jets. Measurements in pp collisions will provide significant constraints on the gluon fragmentation functions, particularly in the case when the pion, kaon or proton assume a large fraction of the parent gluon's momentum. Comparisons of these same fragmentation yields in pp and pA will provide new insights on how the quark and gluon hadronization process is modified by a nuclear environment. Looking at this fragmentation in yet another dimension, as a function of particle momentum relative to the jet axis, provides access to the transverse momentum distributions (TMD) in the proton. Information about unpolarized TMD fragmentation functions is sparse, largely because the interpretation of the existing data is complicated by the limited energy of the lepton-proton collisions used to make the measurements. Investigation of TMD fragmentation functions is an essential piece of a worldwide effort to advance our current picture of Quantum Chromodynamics, the formal theory of strong interactions within the Standard Model of particle physics. This grant will also allow the PI, a postdoctoral associate and a graduate student to maintain their current efforts in the muon g-2 experiment at Fermilab. Contributions will include the development and tuning of the g-2 GEANT based simulation software package, the evaluation of beam dynamics systematic errors that require simulation and the Q-method precession analysis of data taken in Runs 2 & 3.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.

该奖项支持两个独立的实验项目，每个项目都旨在探索我们宇宙最基本的结构。其中一个项目将研究在高能质子-质子碰撞中产生的夸克和胶子如何产生新的夸克和胶子，并最终联合收割机形成构成可见宇宙的粒子。这些研究将揭示量子色动力学的本质，这是一种描述强作用力的理论，强作用力是构成粒子物理标准模型的三种基本力之一。另一个项目旨在发现标准模型中尚未包含的新的力和粒子的信号。费米国家实验室的g-2实验旨在精确测量μ子的磁性，μ子是一种基本粒子，其特性与电子非常相似，但质量是电子的200倍。这个实验是布鲁克海文国家实验室近20年前进行的早期测量的第二代，与标准模型的理论计算略有不同。费米实验室测量的第一个结果已经公布，它与早期的测量结果一致，但精度更高。 实验和标准模型之间的差异指出了标准模型之外的力和/或粒子对μ子磁矩的可能贡献。 费米实验室g-2合作正在分析和收集更多的数据集，目标是进一步减少测量的不确定性，并推动与标准模型预测的发现水平差异。该补助金支持的实验将为本科生和研究生提供必要的工具和经验，以继续他们在基础研究中的工作，或进入技术劳动力市场，并将他们解决问题的专业知识借给无数领域，包括金融，大数据分析，专利法和医学物理学。获得该奖项资助的本科生将继续有难得的机会体验美国国家实验室的科学文化和基础研究。该奖项将支持PI和两名研究生在相对论重离子对撞机上使用高能pp和pA碰撞，从已识别的π介子分布中提取纵向和横向动量相关的喷流碎裂函数，完全重建的喷流内部的K介子和质子。pp碰撞中的测量将对胶子碎裂函数提供重要的限制，特别是当π介子、K介子或质子占据母胶子动量的很大一部分时。这些相同的碎裂产率在pp和pA的比较将提供新的见解夸克和胶子强子化过程是如何修改的核环境。在另一个维度上观察这种碎裂，作为相对于射流轴的粒子动量的函数，提供了对质子中的横向动量分布（TMD）的访问。 关于非极化TMD碎裂函数的信息很少，主要是因为用于测量的轻子-质子碰撞的能量有限，使现有数据的解释变得复杂。TMD碎裂函数的研究是全世界努力推进量子色动力学的一个重要部分，量子色动力学是粒子物理标准模型中强相互作用的形式理论。这笔赠款还将允许PI，博士后助理和研究生保持他们目前在费米实验室的μ子g-2实验的努力。贡献将包括基于g-2 GEANT的模拟软件包的开发和调整，需要模拟的束流动力学系统误差的评估，以及对2002 - 2003年数据的Q方法进动分析。该奖项反映了NSF的法定使命，并被认为值得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来支持。

项目成果

pythia8 underlying event tune for RHIC energies

RHIC 能量的 pythia8 基础事件调整

• DOI: 10.1103/physrevd.105.016011
• 发表时间: 2022
• 期刊: Physical Review D
• 影响因子: 5
• 作者: Aguilar, Manny Rosales;Chang, Zilong;Elayavalli, Raghav Kunnawalkam;Fatemi, Renee;He, Yang;Ji, Yuanjing;Kalinkin, Dmitry;Kelsey, Matthew;Mooney, Isaac;Verkest, Veronica
• 通讯作者: Verkest, Veronica