Studying Quantum Chromodynamics at LHCb

日常物质的原子核中的质子和中子是由称为夸克和胶子的亚核粒子组成的。该奖项支持的项目将研究夸克和胶子是如何从质子中分散出来的，或者是在高能粒子碰撞中产生的，随后将形成新的束缚态。其他测量将调查被称为颜色的强烈核电荷如何流经质子-质子散射过程，寻找理论上预测的夸克和胶子的新状态，这种状态在相互碰撞的质子之间显示出量子关联。来自欧洲核子研究组织(CERN)大型强子对撞机的数据将用于执行这项研究，作为大型强子对撞机美容(LHCb)实验的一部分。所进行的研究将促进我们对质子等强力束束态的产生以及它们可能相互作用的动力学的理解。该奖项支持的项目将进一步培训来自不同背景的年轻核物理科学家。培训下一代核物理学家对于保持与国家能源和国防需求相关的专业知识以及继续推进核物理和技术方面的应用和非应用研究至关重要。具体地说，这一奖项将使一名博士后学者和五名博士生在LHCb实验上进行核物理指导研究，其中包括一名拉丁裔美国人和另一名非裔美国人。在第二年，来自曼荷莲学院的一名学生将在密歇根大学进行夏季核物理研究。Pi的团队将通过在LHCb进行一系列互补测量来研究高能色荷夸克是如何形成可观察到的色中性束缚态的喷雾的。具体地说，这些测量将比较主要由轻夸克和重夸克引发的喷注中的带电强子分布，包括研究预测的强子产生与夸克质量之间的抑制；通过测量重子和介子的产生作为事件多样性的函数，检查强子弦断裂和夸克合并模型对强子化贡献的证据；以及通过测量产生的超子的自发极化来研究强子化中的自旋-动量关联。拟议的强子化计划将有助于实现最终的长期目标，即能够在统计上预测来自不同味道的高能碎裂夸克的粒子的完全关联分布。单独的测量将通过寻找横向动量相关因子化破裂和颜色纠缠的实验证据来探索色流在强子散射过程中的作用。具体的观测包括近背靠背Z玻色子-强子和Z玻色子-喷注对的关联产生。此外，这些活动还包括为美国主导的LHCb上游跟踪器硅探测器升级的调试和优化做出贡献，以及将其集成到LHCb实时分析框架中。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 protons and neutrons in the atomic nuclei of everyday matter are made of subnuclear particles called quarks and gluons. The project supported by this award will study how quarks and gluons scattered out of a proton or produced in high-energy particle collisions subsequently form new bound states. Additional measurements will investigate how strong nuclear charge, called color, flows through proton-proton scattering processes, searching for a theoretically predicted novel state of quarks and gluons that exhibit quantum correlations across colliding protons. Data from the Large Hadron Collider at the European Organization for Nuclear Research (CERN) will be used to perform the research, as part of the Large Hadron Collider Beauty (LHCb) experiment. The research performed will advance our understanding of how strong force bound states such as protons can be created, and the dynamics of their possible interactions. The project supported by this award will furthermore train young scientists from diverse backgrounds in nuclear physics. Training the next generation of nuclear physicists is critical to maintain expertise relevant to the nation's energy and defense needs and to continue advancing both applied and non-applied research in nuclear physics and technology. Specifically, this award will enable mentored research in nuclear physics on the LHCb experiment by a postdoctoral scholar and five Ph.D. students, including one who is Latina American and another who is African American. In the second year, a student from Mount Holyoke College, an undergraduate institution for women, will perform summer research in nuclear physics at the University of Michigan.The PI’s group will study how high-energy color-charged quarks hadronize into sprays of observable color-neutral bound states by performing a suite of complementary measurements at LHCb. Specifically, the measurements will compare charged hadron distributions in jets initiated predominantly by light versus heavy quarks, including investigation of the predicted suppression of hadron production with the mass of the quark; examine evidence for contributions from string breaking versus quark coalescence models of hadronization via measurements of baryon versus meson production as a function of event multiplicity; and study spin-momentum correlations in hadronization by measurement of spontaneous polarization of produced hyperons. The proposed hadronization program will contribute toward the ultimate, long-term goal of being able to predict statistically the fully correlated distributions of particles from different flavor high-energy fragmenting quarks. Separate measurements will explore the role of color flow in hadronic scattering processes by searching for experimental evidence of transverse-momentum-dependent factorization breaking and color entanglement. The specific observables include correlated production of nearly back-to-back Z boson-hadron and Z boson-jet pairs. The activities furthermore include contributions to the commissioning and optimization of the U.S.-led Upstream Tracker silicon detector upgrade for LHCb as well as its integration into the LHCb real-time-analysis framework.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.