NSCI SI2-SSE: The N-Jettiness Software Framework for Precision Perturbative QCD Calculations in Particle and Nuclear Physics

该项目将开发所需的计算工具，以解释来自粒子加速器的日益精确的仪器数据，例如世界上最大、最强大的大型强子对撞机(LHC)。这些计算将在最小的尺度上提高我们的物理学知识，并可能揭示测量结果与理论(粒子物理标准模型)之间的偏差。对最近发现的希格斯玻色子的详细研究，以及对标准模型偏差的搜索，将在未来几十年指导物理学界。这一计划的成功将依赖于日益复杂和精确的理论计算。用美国粒子物理项目优先小组(P5)报告的话来说，这份报告描述了高能物理的下一个十年：“希格斯粒子的全部发现潜力将通过对希格斯粒子性质的百分比级精确研究来释放。”实现如此精确的预测是一个巨大的理论和计算挑战。项目成员开发了一种新的必要计算方法，特别适合在美国最大的高性能计算系统上运行。这种方法使以前得不到的结果成为可能，未来类似的快速进展也大有可为。这个项目中的软件开发将提供必要的工具来回答基础物理学面临的一些最悬而未决的问题：希格斯玻色子的根本起源是什么？我们能在大型强子对撞机上发现暗物质吗？使质子具有观察到的自旋的微观机制是什么？通过初级科学家参与回答这些问题，年轻一代将接受应用尖端计算知识回答未来科学问题的培训。该项目的主要目标是开发和部署将N-Jettness减法用于微扰QCD计算的代码，以满足粒子和核物理对撞机实验日益增长的精度需求。该理论框架通过将公开可用的次要引导顺序(NLO)代码扩展到次要引导顺序(NNLO)，非常有效地利用了以前社区在软件开发中的投资，其中扩展参数是强耦合常数。这一改进将其可实现的理论精度提高了一个数量级，同时保持了用户社区熟悉的界面。该项目的具体目标如下：将大型强子对撞机喷气生产过程的NNLO校正公开发布为既快速又用户友好的公共模拟代码；扩展遇险功能，一个为RHIC和未来的电子离子对撞机的精确模拟设计的新代码；为未来的多核计算架构准备这些精密模拟工具，这些多核计算架构的特点是每个核心的内存更小。N-Jettness减法针对美国政府已投入巨资的大规模并行计算架构进行了优化，从而推进了国家战略计算倡议的目标。该项目得到了计算机与信息科学与工程局的高级网络基础设施办公室、数学和物理科学局的物理司和多学科活动办公室的支持。

This project will develop computational tools needed to interpret increasingly precise instrument data from particle accelerators such as the world's largest and most powerful, the Large Hadron Collider (LHC). These computations will advance our knowledge of physics at the smallest scales and may potentially reveal deviations between measurements and theory (the Standard Model of particle physics). The detailed scrutiny of the recently-discovered Higgs boson and searches for deviations from the Standard Model will guide the physics community for the coming decades. The success of this program will rely upon increasingly intricate and precise theoretical calculations. In the words of the U.S. Particle Physics Project Prioritization Panel (P5) report which describes the next decade of high energy physics: "The full discovery potential of the Higgs will be unleashed by percent-level precision studies of the Higgs properties." The difficulty in achieving predictions at this precision is an enormous theoretical and computational challenge. The project members have developed a novel approach to the necessary calculations that is especially adapted to run on the nation's largest high-performance computing systems. This method has made previously unobtainable results possible, and there is great promise for similar future rapid progress. The software development in this project will provide the tools needed to answer some of the most outstanding issues facing fundamental physics: What is the underlying origin of the Higgs boson? Can we discover dark matter at the LHC? What is the microscopic mechanism which gives the proton its observed spin? Through the involvement of junior scientists in answering these questions the younger generation will be trained in applying cutting-edge computing knowledge to answer future scientific questions.The primary goal of this project is the development and deployment of codes incorporating the N-jettiness subtraction approach to perturbative QCD calculations in order to address the ever-increasing precision needs of collider experiments in particle and nuclear physics. This theoretical framework very effectively uses previous community investments in software development by extending publicly-available next-to-leading-order (NLO) codes to next-to-next-to-leading order (NNLO), where the expansion parameter is the strong coupling constant. This advance improves their achievable theoretical precision by an order of magnitude, while maintaining the interface familiar to the user community. The specific objectives of this project are as follows: the public release of NNLO corrections for jet production processes at the LHC into a public simulation code that is both fast and user-friendly; the expansion of the functionality of DISTRESS, a new code designed for precision simulations for RHIC and a future electron-ion-collider; the preparation of these precision simulation tools for future multi-core computing architectures that feature smaller memory per core. The N-jettiness subtraction approach is optimized for the massively-parallel computing architectures in which the United States government has invested heavily, and therefore advances the goals of the National Strategic Computing Initiative.This project is supported by the Office of Advanced Cyberinfrastructure in the Directorate for Computer & Information Science and Engineering, the Physics Division and Office of Multidisciplinary Activities in the Directorate of Mathematical and Physical Sciences.