Ab initio theory of light and medium mass nuclei

原子核是由质子和中子与源自量子色动力学基本理论的力相互作用而形成的量子多体系统。从组成核子及其核子间的相互作用出发，准确处理原子核一直是核物理学的一个重要目标。 这个项目的目标是发展一种预测轻质量和中等质量原子核的核结构和核反应的从头算理论。这样的理论对于理解在TRIUMF的ISAC这样的稀有同位素设施中研究的奇异核，对于理解对天体物理学很重要的核反应，对于理解对未来的能源产生很重要的聚变反应，以及对于测试核过程中的基本对称性，都是必要的。同时，它提供了关于用作这些计算输入的核子间迭代作用的质量的反馈，并最终有助于提高我们对核子-核子相互作用的知识，特别是仍然不完全理解的三核子相互作用的知识。 在这个方案中，我们结合了能够描述轻核束缚态的从头算核结构方法和描述原子团簇反应的微观团簇方法。由此产生的方法提供了从质子和中子之间的核子间相互作用开始的束缚核态和非束缚核态的统一描述。我们将应用这种方法来提高我们对9He、11N或17C等奇异核的理解，以描述11Be或11Li等晕核。使用包括三核子相互作用在内的最先进的核力，我们将计算对天体物理重要的核反应速率，包括7Be(p，伽马)8B，3He(4He，伽马)7Be，2H(阿尔法，伽马)6Li和4He(nn，伽马)6He，这些反应在宇宙环境中发生的低能很难或不可能测量到。我们还将研究与未来能量产生相关的聚变反应，如~3H(d，n)4He和非中子态11B(p，α)8BE。我们将研究6He的β衰变，这是一项超越标准模型的重要物理测试。我们还将致力于中等质量原子核的从头算研究，主要目标之一是改进无中微子双β衰变矩阵元的计算。最后，这个项目的一个长期目标是计算对恒星合成12C和16O很重要的反应。预计对这些反应的理论理解的复杂性相当于大规模的计算。

Atomic nuclei are quantum many-body systems made by protons and neutrons interacting with forces that originate from the fundamental theory of Quantum Chromo-Dynamics. The exact treatment of nuclei starting from the constituent nucleons and the inter-nucleon interactions among them has been a long-standing goal in nuclear physics. The goal of this project is to develop a predictive ab initio theory of nuclear structure and nuclear reactions for light and medium mass nuclei. Such a theory is needed for understanding of exotic nuclei investigated at rare isotope facilities like ISAC at TRIUMF, for understanding of nuclear reactions important for astrophysics, for understanding of fusion reactions important for the future energy generation as well as for the testing of fundamental symmetries in nuclear processes. At the same time, it provides a feedback on the quality of inter-nucleon iteractions used as input to these calculations and ultimately helps to improve our knowledge of the nucleon-nucleon interaction, and in particular of the still-not-completely-understood three-nucleon interaction. In this proposal, we combine an ab initio nuclear structure approach capable to describe bound states of light nuclei with a microscopic cluster method developed to describe reactions of nuclear clusters. The resulting method provides a unified description of both bound and unbound nuclear states starting from inter-nucleon interactions among protons and neutrons. We will apply this method to improve our understanding of exotic nuclei such as 9He, 11N, or 17C, to describe halo nuclei like 11Be or 11Li. Using state-of-the-art nuclear forces including the three-nucleon interaction, we will calculate rates of nuclear reactions important for astrophysics including 7Be(p,gamma)8B, 3He(4He,gamma)7Be, 2H(alpha,gamma)6Li and 4He(nn,gamma)6He that are difficult or impossible to measure at low energies at which these reactions occur in cosmic environments. We will also investigate fusion reactions such as 3H(d,n)4He and the aneutronic 11B(p,alpha)8Be relevant for future energy generation. We will study beta decay of 6He that is being measured as an important test of physics beyond the Standard Model. We will also contribute to ab initio investigatinos of medium mass nuclei with one of the major goals to improve calculations of the neutrinoless double-beta decay matrix elements. Finally, a long-term goal of this project is the calculation of reactions important for stellar synthesis of 12C and 16O. It is anticipated that the complexity of theoretical understanding of these reactions equires exa-scale computing.