Ab initio nuclear theory for applications in astrophysics and tests of fundamental symmetries

从头算核理论在天体物理学和基本对称性测试中的应用

• 批准号: SAPIN-2022-00019
• 负责人: Navratil, Petr
• 金额: $ 8.01万
• 依托单位: TRIUMF
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=765952
• 关键词: Ab; initio; nuclear; theory; applications

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 to understand nuclear reactions important for astrophysics, to calculate electroweak reactions and decays of nuclei, to provide nuclear physics input for tests fundamental symmetries and for search for physics beyond the standard model, to understand fusion reactions important for the future energy generation, and to interpret the structure of exotic nuclei investigated at facilities like ISAC/ARIEL at TRIUMF. At the same time, it provides a feedback on the quality of inter-nucleon interactions 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 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 for example to improve our understanding of reactions with 8Be as the composite system, e.g., the transfer 7Li(p,n)7Be and electromagnetic captures 7Li(p,?)8Be and 7Li(p,e+e--)8Be relevant for Big Bang nucleosynthesis and the 7Li puzzle as well as for the recently claimed observation of a 17 MeV fifth--force boson. We will investigate 10C?10B and 14O?14N beta decays relevant for probing of the CKM matrix unitarity, an important test of the standard model. We will also focus on the 6He?6Li transition including predictions of the ß--energy spectrum investigated experimentally at present, which is one of the precision tests looking for evidence of interactions beyond the standard model. As experiments are proposed to measure nuclear spin -dependent parity- violating effects in polyatomic molecules, we will continue our calculations of anapole moments of the involved nuclei and focus on contributions from different terms of parity -violating nucleon-nucleon interaction. A similar sensitivity study will be performed in calculations of nuclear electric dipole moments. Finally, a long-term goal of this project is the calculation of reactions important for stellar synthesis of 12C and 16O. This is now within reach as the a--a scattering capability has been developed. The complexity of theoretical understanding of these reactions requires exa-scale computing.

原子核是由质子和中子与源自量子色动学基本理论的力相互作用而形成的量子多体系统。从核子组成和核子间相互作用出发，对原子核进行精确的处理一直是核物理学的一个长期目标。该项目的目标是发展一个预测的从头计算理论的核结构和核反应的轻和中等质量的核。需要这样的理论来理解对天体物理学重要的核反应，计算电弱反应和原子核的衰变，为测试基本对称性和寻找标准模型之外的物理学提供核物理输入，理解对未来能源产生重要的聚变反应，并解释在TRIUMF的ISAC/ARIEL等设施中研究的奇异核的结构。它提供了关于核子间相互作用的质量的反馈，作为这些计算的输入，并最终有助于提高我们对核子-核子相互作用的认识，特别是对仍未完全理解的三核子相互作用的认识。在这个建议中，我们结合联合收割机的从头计算核结构的方法能够描述束缚态的核与微观集团方法发展来描述核集团的反应。由此产生的方法提供了一个统一的描述从质子和中子之间的核子间相互作用的束缚和非束缚的核状态。例如，我们将应用这种方法来提高我们对8Be作为复合体系的反应的理解，例如，7 Li（p，n）7 Be的转移和7 Li（p，？）8Be和7 Li（p，e+e--）8Be与大爆炸核合成和7 Li之谜以及最近声称的17 MeV第五力玻色子的观测有关。我们将研究10 C？10 B和14 O？14 N β衰变与CKM矩阵酉性的探测有关，这是标准模型的一个重要测试。我们还将关注6 He？~ 6Li跃迁，包括对目前实验研究的~ 6Li能谱的预测，这是寻找标准模型以外相互作用证据的精确检验之一。随着实验被提出来测量多原子分子中与核自旋相关的宇称违反效应，我们将继续计算所涉及的核的阿那极矩，并关注不同项的宇称违反核子-核子相互作用的贡献。将在计算核电偶极矩时进行类似的灵敏度研究。最后，该项目的长期目标是计算对恒星合成12 C和16 O重要的反应。随着α-α散射能力的发展，这一点现在已经触手可及。理论上理解这些反应的复杂性需要exa尺度的计算。