Electroweak reactions in Low-energy Nuclear Physics

核物理中的许多重要反应不能用目前可用的实验技术来测量。例如，在太阳中，两个质子融合形成重离子(一个中子和一个质子的束束态)过程的反应概率是一个重要的过程，但不能通过实验测量；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，量化理论上的不确定性变得很重要。这个项目将针对具体的反应来解决这些问题。将使用解析和数值计算来确定与天体物理相关的反应速率，并将提供新的核间相互作用的参数化。具体地说，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。该工具是一个扩展，可以通过以受控方式引入附加参数来系统地改进该工具，以提高交互模型的精度。数值技术将被用来确定这种方法的固有误差，将相互作用参数化，并计算选定过程的反应速率。对由此产生的不确定性进行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一个极好的培训基础，并将为依赖核物理的技术提供所需的劳动力，这些技术与安全、能源和卫生保健部门有关。研究生将熟悉在工业工作中有用的数值方法。这个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，我们将在所谓的无点有效场论的统一框架内计算少核子系统中的一些弱过程。具体地说，将对测量良好的氚衰变半衰期进行处理，并用来确定在这一框架内实现质子-质子聚变的高精度和氦-3上的弱质子捕获所需的参数。第二个重点将集中在理解哈密顿量的内在误差和与之相关的电弱电流，这些电流是由所谓的点有效场论产生的。PI将使用新的数值优化/拟合技术来建立手性势和相关的电弱电流的排序方案，该方案反映了哈密顿按序排列的固有误差。然后，PI将与他的合作者一起，使用这些结果来计算可观测数据，如半衰期或总衰减率，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.