Nuclear Structure and Reactions from Effective Field Theory

有效场论的核结构和反应

基本信息

批准号：
1913620
负责人：
Gautam Rupak
金额：
$ 27万
依托单位：
Mississippi State University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-09-01 至 2024-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1913620&HistoricalAwards=false
关键词：
Nuclear Structure Reactions Effective Field

项目摘要

The fundamental interactions in nuclear physics are described by the theory of Quantum Chromodynamics (QCD). At low energies, QCD is a strongly interacting theory that cannot be solved from first principles in a pencil-and-paper calculation. The effective field theory (EFT) formulation provides a complementary framework where nuclear properties at low energy can be systematically calculated. As such, EFT calculations can provide accurate input for astrophysical models of element synthesis that cannot be obtained in direct experimental measurements. In this project, the PI and his collaborators will use numerical methods defined on a space-time lattice to calculate properties of medium-light atomic nuclei (mass number up to around 40) using EFT. The PI will use Bayesian statistics to quantitatively compare competing EFT formulations. The latter is useful in constructing an accurate and systematic theory for low energy nuclear physics. Broader impacts of the research include training of graduate students in numerical and analytical work for an academic or industry career benefiting society.The current project builds on the lattice EFT pinhole algorithm that was previously introduced by the PI. This algorithm allows for the calculation of the charge and matter distribution (in the center-of-mass coordinate) in Monte Carlo simulations that is necessary to couple external electro-weak currents to atomic nuclei. The PI aims to calculate electromagnetic moments of light nuclei. The same method will be used to calculate neutrino-nucleus coherent scattering that is sensitive to the neutron matter distribution. This cross section serves as a background in dark matter search experiments. The PI will study also low energy nuclear reactions involving halo nuclei using Bayesian statistics. Halo nuclei are characterized as weakly bound quantum systems and play an important role in element synthesis in the Big Bang and stellar burning. Bayesian analysis provides a natural framework to incorporate EFT assumptions about naturalness of sizes of couplings in parameter estimation. It also allows quantitative comparison of competing theories and aids in model selection. This project will support the science programs at planned major U.S. investments in rare isotope beam experiments.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.

核物理学中的基本相互作用由量子染色体学理论（QCD）描述。在低能量下，QCD是一种强烈相互作用的理论，在铅笔和纸计算中无法从第一原理解决。有效的场理论（EFT）公式提供了一个补充框架，可以系统地计算低能处的核性质。因此，EFT计算可以为元素合成的天体物理模型提供准确的输入，这些输入在直接实验测量中无法获得。在这个项目中，PI和他的合作者将使用时空晶格上定义的数值方法来计算使用EFT的中等光原子核（质量数量均达40次）的性质。 PI将使用贝叶斯统计数据来定量比较竞争的EFT配方。后者有助于为低能核物理构建准确有系统的理论。这项研究的更广泛的影响包括在学术或行业职业中对研究生进行培训，从而使社会受益。当前的项目以PI先前引入的晶格EFT针孔算法为基础。该算法允许在蒙特卡洛模拟中计算电荷和物质分布（在质量中心坐标中），这是将外部电流电流与原子核相结合的必要条件。 PI旨在计算光核的电磁力矩。将使用相同的方法来计算对中子物质分布敏感的中微子核相干散射。该横截面是暗物质搜索实验的背景。 PI还将研究使用贝叶斯统计数据的低能核反应。光环核的特征是弱结合的量子系统，并在大爆炸和恒星燃烧中的元素合成中起重要作用。贝叶斯分析提供了一个自然框架，可以在参数估计中纳入有关耦合大小的自然性的EFT假设。它还允许对竞争理论和辅助模型选择进行定量比较。该项目将支持计划在稀有同位素束实验的美国大型投资中的科学计划。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响评估标准，被认为值得通过评估来获得支持。