Electroweak reactions in Low-energy Nuclear Physics

核物理学中许多重要的反应不能用现有的实验技术来测量。例如，两个质子聚变形成氘核（一种中子和质子的束缚态）过程的反应概率在太阳中是一个重要的过程，但无法通过实验测量；只有理论计算才能提供这个速率。在缺乏实验指导的情况下，量化理论不确定性就变得很重要。本项目将针对这些问题进行具体的反应。分析和数值计算将用于确定与天体物理有关的反应速率，并将提供核间相互作用的新参数化。具体来说，PI和他的学生将使用一种被称为有效场论的理论工具构建的相互作用。该工具是一种扩展，可以通过以可控的方式引入额外的参数来系统地改进，以提高交互模型的准确性。数值技术将用于确定该方法的固有误差，参数化相互作用，并计算选定过程的反应速率。对所产生的不确定性的量化将提高我们对核间相互作用的理解。该项目还将为研究生和本科生提供良好的培训场所，并将有助于培养与安全、能源和保健部门相关的依赖核物理学的技术方面所需的劳动力。研究生将熟悉在工业中工作时有用的数值方法。该项目遵循双管齐下的策略，旨在利用有效场论提高我们对弱过程的理解。首先，将在所谓无轴有效场论的统一框架内计算少量核子系统中的一些弱过程。具体来说，我们将对氚的衰变半衰期进行处理，并将其用于确定一个参数，该参数在这个框架内用于高精度的质子-质子聚变和氦-3上的弱质子捕获。第二个侧重点将集中在理解哈密顿量的固有误差以及与之相关的由所谓的先锋有效场论产生的弱电。PI将使用新颖的数值优化/拟合技术来建立手性势和相关弱电电流的排序方案，该方案反映了哈密顿函数逐级的固有误差。PI将与他的合作者一起，利用这些结果计算诸如半衰期或总衰变率等可观测值，以达到新的精度和正确的误差估计。由此产生的相互作用和电流将提供给核理论界。

Many important reactions in nuclear physics cannot be measured with currently available experimental techniques. For example, the reaction probability of the process in which two protons fuse to form a Deuteron (a bound state of a neutron and a proton) is an important process in the sun, but cannot be measured experimentally; only theoretical calculations can provide this rate. In the absence of guidance from experiment, it becomes important to quantify theoretical uncertainties. This project will address these issues for specific reactions. Analytical and numerical calculations will be used to determine reaction rates for astrophysically-relevant reaction rates, and new parametrizations of the internuclear interaction will be provided. Specifically, the PI and his students will use interactions that have been constructed using a theoretical tool known as effective field theory. This tool is an expansion that can be systematically improved by introducing, in a controlled manner, additional parameters to increase the accuracy of the interaction model. Numerical techniques will be used to determine the intrinsic error of this approach, parametrize the interaction, and calculate the reaction rates for selected processes. A quantification of resulting uncertainties will improve our understanding of the internuclear interaction. This project will also provide an excellent training ground for graduate and undergraduate students and will contribute to a needed workforce in those technologies that rely on nuclear physics, which are relevant to security, energy and the health care sector. Graduate students will become familiarized with numerical methods that can be useful when working in industry.This project follows a two-prong strategy that aims at improving our understanding of weak processes using effective field theory. Firstly, a number of weak processes in few-nucleon systems will be calculated within the unified framework of the so-called pionless effective field theory. Specifically, the well-measured decay half-life time of tritium will be treated and used to fix a parameter that within this framework is required for a high-accuracy of proton-proton fusion and weak proton capture on Helium-3. The second prong will focus on understanding the intrinsic error of Hamiltonians and associated electroweak currents generated with the so-called pionfull effective field theory. The PI will use novel numerical optimization/fitting techniques to establish an ordering scheme for the chiral potential and the associated electroweak currents that reflects the intrinsic error of the Hamiltonian order-by-order. Together with his collaborators, the PI will then use these results to calculate observables such as half-life times or total decay rates to new accuracy and with correct error estimates. The resulting interactions and currents will be made available to the nuclear theory community.