Nuclear Structure and Reactions from Effective Field Theory

核物理学的基础研究是对原子核的研究。所有已知的原子核有数千种，其中大多数是短命的。在大爆炸核合成和恒星演化过程中，短寿命的奇异核在稳定元素的合成中起着重要的作用。奇异核在超新星遗迹的元素合成中也起着重要的作用。在地球上的实验室中，通常很难获得元素合成反应发生的温度和密度。理论计算在这些研究中起着重要的作用。应用有效场理论（EFT）方法计算晕核的性质。这些是奇异的原子核，含有多余的质子或中子，在核心周围形成晕。EFT使系统的第一原理计算，提供严格的不确定性估计，在许多天体物理模型的元素合成是必要的。非对称核物质的性质也使用称为格子EFT的数值方法计算。这对研究中子星和黑洞碰撞产生的引力波很重要。 该研究的更广泛影响包括培训研究生从事数值和分析工作，以造福社会的学术或工业职业。 该项目建立在首席研究员（PI）对晕核和晶格EFT的过去工作的基础上，这些工作部分由以前的美国国家科学基金赠款资助。晕核在核图上靠近稳定边缘的地方很丰富。EFT依赖于物理系统中能量尺度的分离来构建低能量近似的系统扩展。晕系统中价核子的小分离能是理想的。研究了强库仑力作用下的耦合通道形式的多通道反应。考虑了锂-8和硼-8的电荷半径，以及氚和氦-3与价核子的反应。贝叶斯分析用于提供不确定性估计，并开发一个强大的反应理论。利用格点EFT研究了中子星星密度和温度相关条件下非对称核物质的性质。在这些研究中使用了PI在早期工作中开发的针孔算法。数值晶格方法允许我们使用EFT中导出的相互作用进行涉及数十个质子和中子的Monte Carlo计算。该项目的研究与美国在稀有同位素束实验方面的重大投资有关。该奖项反映了NSF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。

Fundamental research in nuclear physics is the study of atomic nuclei. The list of all known nuclei, most of them short-lived, is in the thousands. The short-lived and exotic nuclei play an important role in the synthesis of the stable elements during Big Bang Nucleosynthesis and stellar evolution. Exotic nuclei also play an important role in element synthesis in supernova remnant sites. The temperatures and densities at which the reactions responsible for element synthesis occur are often difficult to access in terrestrial laboratories. Theory calculations play an important role in these studies. The effective field theory (EFT) formalism is applied to calculate the properties of halo nuclei. These are exotic nuclei that have excess protons or neutrons that form a halo around a core. EFT enables systematic first-principles calculations that provide rigorous uncertainty estimates that are necessary in many astrophysical models of element synthesis. Properties of asymmetric nuclear matter are also calculated using a numerical method called lattice EFT. These are important in the study of gravitational waves from colliding neutron stars and blackholes. Broader impacts of the research include training of graduate students in numerical and analytical work for an academic or industry career benefiting society. This project builds on past work by the principal investigator (PI) on halo nuclei and lattice EFT that were partly funded by previous U.S. National Science Foundation grants. Halo nuclei are abundant on the nuclear chart near the edge of stability. EFT relies on the separation of energy scales in physical systems to construct a systematic expansion for low-energy approximations. The small separation energy of the valence nucleons in halo systems is ideal for this. Multi-channel reactions in a coupled-channel formalism in the presence of strong Coulomb forces are studied. Charge radii of lithium-8 and boron-8, reactions involving triton and helium-3 with valence nucleons are considered. Bayesian analysis is used to provide uncertainty estimates and develop a robust reaction theory. Properties of asymmetric nuclear matter under conditions relevant to neutron star densities and temperatures are studied using lattice EFT. The Pinhole algorithm developed in earlier work by the PI is used in these studies. The numerical lattice method allows us to perform Monte Carlo calculations involving tens of protons and neutrons using interactions derived in EFT. The research in this project ties in with major U.S. investment 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.