Ab initio theory for major questions in subatomic physics

也许是宇宙中最复杂的量子系统，原子核的许多方面与自然界中一些最深刻的问题交织在一起。长期以来，现代核理论一直被认为是一门现象学学科，现在的目标是从头开始面对这些问题：作为一门能够提供具有量化不确定性的可靠预测的第一原则学科。要做到这一点，我们必须首先建立质子和中子结合到原子核中的作用力的一致描述，以及只从这些相互作用出发解决核多体问题的方法。*我之前的发现拨款对于建立价空间介质中相似重整化群(VS-IMSRG)作为一个强大的从头计算多体工具至关重要。凭借大空间方法的精确度和壳模型的多功能性，VS-IMSRG目前的独特之处在于它基本上能够计算质量为100的所有原子核的所有性质。这项发现拨款的中心重点将是大力推动提高准确性，估计模型不确定性，并扩大物理覆盖范围，以迅速利用这一进展。有了足够的支持，我们将直接有助于理解加拿大亚原子物理长程计划中列出的七个“亚原子物理大问题”中的五个。VS-IMSRG的范围很广，应用于奇异原子核提供了一些最令人兴奋的可能性，以理解原子核结构是如何从核力中出现的。我们将讨论整个图表中的主要核结构问题，如轻质量和中等质量区域中核(质子和中子滴线)的存在限度。此外，我们将预测新魔数在未探索地区的演变，以指导未来的实验工作。从长远来看，我们将为r过程核合成模拟提供第一性原理数据，模拟宇宙中重元素的形成。此外，我们还将讨论与核相关的一些最重要的问题--弱物理。其中最突出的是无中微子双β衰变的核矩阵元素，这是从一个潜在的实验发现中提取绝对中微子质量标度所必需的。轻候选星48Ca76Ge和82Se的从头计算正在进行中，并将达到130Te和136Xe。同样，为了理解暗物质的本质，需要WIMP-原子核截面来解释大规模直接探测搜索的结果。我们将提供第一个WIMP-原子核弹性散射结构因子的从头计算，其中对轻候选者的计算正在进行中，并将扩展到129,131Xe。最后，为了理解电弱尺度下的物理，我们将提供从头算输入来提取GV和CKM夸克混合矩阵的上下分量。

Perhaps the most complicated quantum systems in the universe, the many facets of atomic nuclei are intertwined with some of the most profound questions in nature. Long considered a phenomenological discipline, modern nuclear theory now aims to confront these questions from the ground up: as a first-principles discipline capable of providing reliable predictions with quantified uncertainties. To do this we must first develop a consistent description of the forces which bind protons and neutrons into nuclei, as well as methods which solve the nuclear many-body problem starting only from those interactions.******My previous Discovery Grant was crucial for establishing the valence-space in-medium similarity renormalization group (VS-IMSRG) as a powerful ab initio many-body tool. With the accuracy of large-space methods, but the versatility of the shell model, the VS-IMSRG is currently unique in its capability to calculate essentially all properties of all nuclei up to the mass 100 region. The central focus of this Discovery Grant will be a strong push to improve accuracy, estimate model uncertainty, and expand the physics reach to capitalize quickly on this progress. With sufficient support we will contribute directly to understanding five of the seven "Big Questions in Subatomic Physics", as laid out in the Canadian Subatomic Physics Long Range Plan.******The range of the VS-IMSRG is broad, and applications to exotic nuclei present some of the most exciting possibilities to understand how the structure of nuclei emerges from nuclear forces. We will address major nuclear structure issues across the chart such as the limits of existence of nuclei (the proton and neutron driplines) in the light and medium-mass regions. Furthermore, we will predict the evolution of new magic numbers in unexplored regions to guide future experimental efforts. In the long term we will contribute first-principles data for r-process nucleosynthesis simulations modeling the formation of heavy elements in the universe.******In addition we will address some of the most important questions related to nuclear-weak physics. The most prominent of these is the nuclear matrix element for neutrinoless double beta decay, which is necessary to extract the absolute neutrino mass scale from a potential experimental discovery. Ab initio calculations are underway for the light candidates 48Ca 76Ge and 82Se and will reach 130Te and 136Xe. Similarly for understanding the nature of dark matter, WIMP-nucleus cross sections are needed to interpret results of large-scale direct-detection searches. We will provide the first ab initio calculations of WIMP-nucleus elastic-scattering structure factors, where calculations for light candidates are underway, and will be extended to 129,131Xe. Finally for understanding physics at the electroweak scale, we will provide ab initio input to extract Gv and the up-down component of the CKM quark-mixing matrix.