Research in Strong-Interaction Theory

强相互作用是质子和中子结合成原子核的原因。提高对这一过程的定量理解，不仅对美国实验设施的基础核研究至关重要，而且对天体物理学的进步、对中微子性质的实验以及对能源和国土安全的应用都至关重要。一个精确计算核结构和核反应的时代正在到来，这在一定程度上得益于NSF对pi的资助。已开发的工具和诊断方法将用于应对这一进展所带来的一系列问题。这些问题包括改进力的描述和原子核微观计算的其他输入，应用新方法来评估理论不确定性，以及改进从实验中提取的信息，使其对模型假设的依赖降到最低。本科生、研究生和博士后研究人员在开展拟议活动时所接受的培训，直接有助于建设一支多样化的科学队伍。学生和博士后必须使用的分析和数值计算的组合为学术和工业研究做了极好的准备，这被该小组过去成员的良好记录所证实。该项目要解决的具体问题包括鲁棒不确定性量化、有效场论（EFT）的参数估计、EFT的一致算子和重整化群（RG）方法、理解调节器伪像、制定多体功率计数、解释高动量/短距离物理（包括短程相关性）的作用，以及从实验中提取与过程无关的量。项目将适用于核子间相互作用，少体和多体系统，以及电弱探针。具体使用的工具包括EFT的贝叶斯统计方法、基外推方法、多体贡献分析、接触（无点式）EFT和相似RG （SRG）进化。这些工具在攻击问题和扩展应用程序方面提供了相互连接；它们将继续发展，并将广泛提供。目标应用包括强子和核问题的贝叶斯参数估计和模型选择，解决多体算子增长的新SRG发生器，少体系统的一致淘汰反应，以及使用无通道EFT研究算子进化和评估微扰与非微扰方法。这些都有助于实现与模型无关的原子核微观计算的目标。这些项目将影响低能核物理学的前沿问题，如远离稳定的原子核物理学，这与天体物理学和即将到来的稀有同位素光束设施（FRIB）以及杰斐逊实验室有关。

The strong interaction is responsible for the binding of protons and neutrons into atomic nuclei. Improved quantitative understanding of how this happens is essential not only for fundamental nuclear research at US experimental facilities but for progress in astrophysics, for experiments on the nature of neutrinos, and for applications to energy and homeland security. An era of precision calculations of nuclear structure and reactions is underway, enabled in part by research results from previous NSF grants to the PIs. Tools and diagnostics that have been developed will be applied to confront a range of issues raised by this progress. These issues include improving the description of forces and other inputs for microscopic calculations of nuclei, applying new methods to assess the theoretical uncertainties, and improving the extraction of information from experiment that minimally depends on model assumptions. The training received by undergraduates, graduate students, and postdoctoral research associates in carrying out the proposed activities contributes directly to the building of a diverse scientific workforce. The mix of analytical and numerical computation thethe students and postdocs must employ is excellent preparation for both academic and industrial research, which is validated by the strong track record of past members of the group. Particular issues to be addressed by this project include robust uncertainty quantification, parameter estimation for effective field theory (EFT), consistent operators for EFT and renormalization group (RG) methods, understanding regulator artifacts, formulating many-body power counting, explicating the role of high-momentum/short-distance physics (including short-range correlations), and extracting process-independent quantities from experiment. Projects will apply to inter-nucleon interactions, few-body and many-body systems, and electroweak probes. Specific tools to be used include Bayesian statistical methods for EFT, basis extrapolation methods, analysis of many-body contributions, contact (pionless) EFT, and similarity RG (SRG) evolution. These tools provide interconnections in attacking issues and extending applications; they will continue to be developed and will be made widely available. The target applications include Bayesian parameter estimation and model selection for hadronic and nuclear problems, new SRG generators to address the growth of many-body operators, consistent knock-out reactions for few-body systems, and the use of pionless EFT to study operator evolution and assess perturbative versus non-perturbative approaches. These all contribute to the goal of model independent, microscopic calculations of nuclei. The projects will impact forefront problems in low-energy nuclear physics such as the physics of nuclei far from stability, which is relevant for astrophysics and the upcoming Facility for Rare Isotope Beams (FRIB), and at Jefferson Laboratory.