The strong force at low energies: from exotic nuclei to fundamental symmetries

低能强力：从奇异核到基本对称

• 批准号: SAPIN-2015-00043
• 负责人: Holt, Jason
• 金额: $ 2.48万
• 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: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=614394
• 关键词: strong; force; low; energies; exotic

One of the central challenges in nuclear physics is to understand and predict the properties of stable and exotic nuclei, for which three-nucleon (3N) forces are crucial and present a current frontier. This project will uniquely apply powerful many-body methods to strongly interacting nuclear systems, systematically implementing 3N forces in many-body calculations of medium-mass and heavier neutron-rich nuclei using similarity renormalization group (SRG) methods in momentum space and in-medium for consistent calculations of valence-shell interactions and electroweak operators. Chiral effective field theory (EFT) provides a systematic basis for nuclear forces including consistent many-body forces and theoretical uncertainties. With theoretical and computational advances, I am in a key position to connect the observations made in the laboratory to the underlying strong interactions governing the properties of nuclei. Applications of this work include predictions of exotic nuclei for rare-isotope beam experiments, such as those at TRIUMF, extreme neutron-rich matter in astrophysics, and the nuclear matrix elements of neutrinoless double-beta decay that probe the nature and mass scale of the neutrino.  I plan to systematically push these studies to heavy neutron-rich isotopes, reaching nickel, tin, and beyond, exploring structural evolution and limits of existence in medium-mass and heavy nuclei and make important first predictions with 3N forces in these regions.  A major future direction of this work will be going beyond semi-magic isotopic/isotonic chains. I have begun to access fluorine and neon isotopes, systematically exploring both proton and neutron driplines above 16O and 40Ca. This will present the first attempts to understand the island of inversion and r-process regions, based on NN+3N forces.  In the past year, I have made progress in applying the many-body formalism to the calculation of effective one- and two-body operators for electroweak transitions, including neutrinoless double-beta decay. First results have been published for light double-beta-decay nuclei 48Ca, 76Ge, and 82Se, where I found that the addition of these effects changed predictions of the neutrinoless double-beta-decay nuclear matrix element by 30-70%. I will apply this formalism combined with recent advances in two-body currents from chiral EFT to microscopically calculate M1, E2, and Gamow-Teller transitions in medium- and heavy-mass nuclei as well as neutrinoless double-beta-decay in heavy systems. Finally, I have recently developed a novel ab initio method, the in-medium SRG, for open-shell nuclei. This provides the first nonperturbative approach to valence-shell Hamiltonians that is feasible in practice. Very promising first results have been obtained with NN+3N forces for the oxygen isotopes and great synergy exits to explore the topics above with this method.

核物理学的核心挑战之一是理解和预测稳定和奇异核的性质，其中三核子（3 N）力是至关重要的，并提出了当前的前沿。该项目将独特地将强大的多体方法应用于强相互作用的核系统，在中等质量和较重的富中子核的多体计算中系统地实施3 N力，在动量空间和介质中使用相似重整化群（SRG）方法，用于一致计算价壳层相互作用和电弱算子。手征有效场论（EFT）为核力提供了一个系统的基础，包括一致的多体力和理论的不确定性。随着理论和计算的进步，我处于一个关键的位置，将实验室中的观察结果与控制原子核性质的潜在强相互作用联系起来。 这项工作的应用包括稀有同位素束实验的奇异核的预测，例如TRIUMF的那些，天体物理学中的极端富中子物质，以及探测中微子的性质和质量尺度的无中微子双β衰变的核矩阵元素。我计划系统地将这些研究推向重富中子同位素，达到镍，锡等，探索中等质量和重核的结构演化和存在极限，并在这些区域用3 N力进行重要的首次预测。这项工作的一个主要未来方向将是超越半魔同位素/等渗链。我已经开始接触氟和氖同位素，系统地探索16 O和40 Ca以上的质子和中子滴线。这将提出第一次尝试了解反转和r-过程区域的岛屿，基于NN+3 N forces. In过去的一年中，我已经取得了进展，在应用多体形式主义的计算有效的一个和两个身体运营商的电弱转变，包括中微子双β衰变。第一个结果已经发表了轻双β衰变核48 Ca，76 Ge和82 Se，我发现这些效应的增加使无中微子双β衰变核矩阵元素的预测改变了30- 70%。我将应用这种形式主义结合最近的进展，在两体电流从手征EFT微观计算M1，E2，和Gamow-Teller过渡在中等和重质量的核，以及在重系统中的中微子双β衰变。最后，我最近发展了一种新的从头计算方法，在介质SRG，开壳层核。这提供了第一个非微扰方法的价壳层哈密顿量是可行的，在实践中。用NN+3 N力对氧同位素进行了初步的研究，取得了很有希望的结果。