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

该奖项资助肯纳索州立大学马尔科·古齐教授的研究活动。欧洲核子研究中心大型强子对撞机(LHC)是世界上最大、最强大的粒子加速器，高能质子束以大约光速运动，在这里碰撞。大型强子对撞机实验的精确测量将高能物理带入了一个新的精确领域，使我们能够加深对物质及其基本成分的结构的了解，并阐明可能的新的物理相互作用。这一研究领域充满活力，其快速发展对国家利益具有高度重要性，因为它促进了基础科学的进步，而基础科学对新发现至关重要。理论和实验分析了大型强子对撞机前所未有的能量对精度的要求。这对于理论和实验之间有意义的比较和对结果的正确解释是必不可少的。在他的研究中，古齐教授的目标是计算精确的理论预测，并使用现象学的有效方法来改善我们对质子结构的现有知识，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。这项拟议的研究也有重大的更广泛的影响：Guzzi教授将让学生参与他的研究，就他的研究结果进行公开演讲，并根据他的研究结果开发新的课程。在技术方面，Guzzi教授将使用对大型强子对撞机产生的顶-夸克对运动学分布的精确理论预测，以减少与部分子分布函数(PDF)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，它们是大型强子对撞机许多重要观测数据理论预测准确性的关键限制因素。拟议项目的第二部分旨在改进在大型强子对撞机上寻找额外的中性矢量玻色子的理论预测，这些玻色子通常被称为Z‘玻色子。它们与标准Z模型玻色子的不同之处在于它们具有不同的质量和耦合。随着上面讨论的质子PDF的改进，以及在LHC Run-II能量和光度下对Drell-yan过程中双轻子对产生的新的精确测量，Guzzi教授将研究普通起源的Z的参数空间，并将仔细检查大量新的物理模型。最后，Guzzi教授将利用高阶微扰理论和最近用于Z玻色子产生的精确LHC测量，高精度地确定质子横向动量相关(TMD)分布的非微扰参数，这种新的角变量具有对非微扰效应非常敏感的优点。TMD分布代表了QCD中因式分解定理的最终前沿，使我们能够有一个统一的框架来描述不同能量方案中的强子反应。这一奖项反映了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。

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.