Precision Theory at the LHC: Strong Interaction Dynamics and New Physics Searches

该奖项资助肯尼索州立大学Marco Guzzi教授的研究活动。欧洲核子研究中心的大型强子对撞机（LHC）是世界上最大、最强大的粒子加速器，高能质子束以接近光速的速度碰撞在一起。大型强子对撞机实验的精确测量将高能物理学带入了一个新的精确领域，使我们能够加深对物质结构及其基本成分的了解，并阐明可能的新物理相互作用。这一研究领域充满活力，其快速发展对国家利益具有重要意义，因为它促进了对新发现至关重要的基础科学的进步。对大型强子对撞机前所未有的能量进行理论和实验分析需要精度。这对于理论和实验之间有意义的比较以及对结果的正确解释是必不可少的。在他的研究中，Guzzi教授旨在计算精确的理论预测，并使用有效的现象学方法来提高我们目前对质子结构的认识，并对基本粒子的标准模型进行严格的测试，以及寻找新物理理论预测的新粒子特征。拟议的研究还具有重要的更广泛的影响：Guzzi教授将让学生参与他的研究，就他的研究成果进行公开讲座，并根据他的研究成果开发新的课程课程。在技术方面，Guzzi教授将对LHC产生的顶夸克对的运动分布进行精确的理论预测，以减少与部分子分布函数（PDF's）相关的不确定性。质子的PDF绘制了其组成夸克和胶子的纵向动量分布，它们是LHC中许多重要观测到的理论预测准确性的关键限制因素。该计划的第二部分旨在改进在大型强子对撞机中寻找额外中性矢量玻色子（通常被称为Z玻色子）的理论预测。它们与标准模型Z玻色子的不同之处在于具有不同的质量和耦合。随着上述质子PDF的改进，以及在LHC Run-II上对drel - yan过程中双轻子对产生的能量和光度的新的精确测量，Guzzi教授将研究一般起源Z的参数空间，并将仔细研究大量新的物理模型。最后，Guzzi教授将利用高阶微扰理论和最近对z -玻色子产生的精确LHC测量，高精度地确定质子横向动量依赖（TMD）分布的非微扰参数，该参数基于一种新的角变量，该角变量具有对非微扰效应非常敏感的优势。TMD分布代表了QCD中分解定理的最终前沿，并允许我们有一个统一的框架来描述不同能量状态下的强子反应。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。

This award funds the research activity of Professor Marco Guzzi at Kennesaw State University. The CERN Large Hadron Collider (LHC) is the world's biggest and most powerful particle accelerator where high energy beams of protons, traveling at approximately the speed of light, collide. Accurate measurements from the LHC experiments brought high-energy physics to a new realm of precision that allows us to deepen our knowledge of the structure of matter and its elementary constituents and to shed light on possible new physics interactions. This field of research is vibrant and its rapid progress is of high importance for the national interest as it promotes advances of fundamental science that are crucial for new discoveries. Theoretical and experimental analyses at the unprecedented energies of the LHC demand precision. This is essential for meaningful comparisons between theory and experiment and a correct interpretation of the results. In his research, Professor Guzzi aims to calculate precise theoretical predictions and use efficient methods for phenomenology to improve our current knowledge of the structure of the proton and set stringent tests on the Standard Model of the elementary particles, as well as search for new particle signatures predicted by theories of new physics. The proposed research also has significant broader impacts: Professor Guzzi will involve students in his research, give public lectures on his research results, and develop new course curricula based on the results of his research.On the technical side, Professor Guzzi will use precise theory predictions for kinematic distributions of top-quark pairs produced at the LHC to reduce the uncertainties associated with parton distribution functions (PDF's). PDF's of the proton map out the longitudinal momentum distribution of its constituent quarks and gluons and they are a crucial limiting factor in the accuracy of theoretical predictions for many important observables at the LHC. A second part of the proposed project aims to improve the theory predictions for searches for extra neutral vector bosons at the LHC, generically referred to as Z' bosons. They differ from the Standard-Model Z boson by having different masses and couplings. With the improvements of the proton PDF's discussed above and with new precise measurements of dilepton pair production in Drell-Yan processes at LHC Run-II energies and luminosities, Professor Guzzi will study the parameter space of Z's of generic origin and will scrutinize a large number of new physics models. Finally, Professor Guzzi will determine with high precision the nonperturbative parameters of the transverse momentum dependent (TMD) distributions of the proton by using high-order perturbation theory and recent precise LHC measurements for Z-boson production in terms of a novel angular variable that has the advantage of being very sensitive to nonperturbative effects. TMD distributions represent the ultimate frontier of factorization theorems in QCD and allow us to have a unified framework in which to describe hadronic reactions in different energy regimes.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.