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，大多数都是短命的，有几千个。在大爆炸核合成和恒星演化过程中，短寿命和外来核在稳定元素的合成中起着重要作用。外来核在超新星遗迹的元素合成中也起着重要的作用。导致元素合成的反应发生时的温度和密度通常很难在陆地实验室中获得。理论计算在这些研究中起着重要的作用。利用有效场论（EFT）的形式化方法计算了晕核的性质。这是一种奇异的原子核，有多余的质子或中子，在核心周围形成晕。EFT使系统的第一性原理计算能够提供严格的不确定性估计，这在许多天体物理元素合成模型中是必要的。非对称核物质的性质也用一种称为晶格EFT的数值方法计算。这些对于研究中子星和黑洞碰撞产生的引力波非常重要。这项研究的更广泛影响包括培养研究生在数值和分析工作方面的学术或工业生涯，造福社会。该项目建立在首席研究员（PI）过去在晕核和晶格EFT方面的工作基础上，这些工作部分由美国国家科学基金会资助。在核图上，靠近稳定边缘的晕核非常丰富。EFT依赖于物理系统中能量尺度的分离来构建低能近似的系统展开。光晕体系中价核子的小分离能是理想的。研究了在强库仑力作用下的多通道反应。考虑了锂-8和硼-8、氚和氦-3与价核子的反应的电荷半径。贝叶斯分析用于提供不确定性估计和发展稳健的反应理论。利用晶格EFT研究了与中子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。数值点阵方法允许我们使用EFT中导出的相互作用来执行涉及数十个质子和中子的蒙特卡罗计算。该项目的研究与美国在稀有同位素束流实验方面的重大投资有关。该奖项反映了美国国家科学基金会的法定使命，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.