Collaborative Research: Innovative ab initio symmetry-adapted no-core shell model for advancing fundamental physics and astrophysics

路易斯安那州立大学的一组研究人员将解决为原子核复杂的动力学建模所固有的重大计算挑战，原子核动力学是一系列天体物理现象的基础。他们将通过使用Blue Waters超级计算机的千万亿级资源来做到这一点。更具体地说，研究人员将对从氧气到Ar的中等质量原子核进行大规模计算，包括作为当前和下一代稀有同位素实验设施重点的奇异不稳定同位素。从恒星爆炸到核反应堆内部，这样的原子核经常被发现是理解极端环境中过程的关键。该研究项目提供的可靠的核结构信息将对天体物理和中微子物理的基础研究问题产生影响，并将在核能等领域具有潜在的应用，从而为国家的能源基础设施做出贡献。将向下一代物理学家提供利用大规模计算资源的培训，该小组将通过提供前所未有的准确性和范围的核结构信息作为公开可用的数据库，供其他科学家使用，从而扩大他们的研究影响。路易斯安那州立大学团队的方法是求解由质子和中子组成的多体量子系统的薛定谔方程，该系统通过与潜在的夸克/胶子相关的现实相互作用进行相互作用。这个问题的解决方案是通过寻找核哈密顿量的本征态和本征值来实现的，核哈密顿量是在物理相关的基础上计算的，该基础利用了原子核的精确和近似对称性。这种对称性的使用是我们模型的一个独特功能，与Blue Waters的功能相结合使解决方案变得可行。也就是说，该团队将采用对称适应的无核心外壳模型方法，该方法由高度可伸缩的计算机代码实现，被称为“LSU3Shell”，该代码已经在Blue Waters系统上展示了良好的可扩展性和性能。计算将提供寿命短的缺乏中子和富含中子的同位素的核性质，而现有的实验数据很少或根本没有，这些数据预计将对X射线爆发可观测性的模拟、对宇宙中存在的许多重元素的合成负责的触发过程以及对标准模型以外的自然界和物理学中的基本对称性的严格测试产生相当大的影响。

A team of researchers at Louisiana State University will address the significant computational challenges inherent to modeling the intricate dynamics of atomic nuclei, which are fundamental to a vast array of astrophysical phenomena. They will do so by employing the petascale resources of the Blue Waters Supercomputer. More specifically, the investigators will carry out large-scale computations of intermediate-mass nuclei from oxygen to argon, including exotic unstable isotopes that are the focus of current and next-generation rare isotope experimental facilities. Such nuclei are often found key to understanding processes in extreme environments, from stellar explosions to the interior of nuclear reactors. Reliable nuclear structure information provided by this research project will have impacts on basic research questions in astrophysics and neutrino physics, and will also have potential applications in areas like nuclear energy, thus contributing to the nation's energy infrastructure. Training in utilizing large-scale computational resources will be provided to, the next generation of physicists, and the team will expand the impact of their research by providing nuclear structure information of unprecedented accuracy and scope as a publicly available database for use by other scientists. The LSU team's approach is to solve the Schrodinger equation for a many-body quantum system composed of protons and neutrons interacting via realistic interactions that are tied to the underlying quark/gluon considerations. The solution to this problem is achieved by finding eigenstates and eigenvalues of the nuclear Hamiltonian, which is computed in a physically relevant basis that capitalizes on exact and approximate symmetries of nuclei. The use of such symmetries is a unique feature of our model, one that coupled with the Blue Waters capabilities makes solutions feasible. Namely, the team will employ the symmetry-adapted no-core shell model approach implemented by a highly scalable computer code, dubbed "LSU3shell", that has already demonstrated good scalability and performance on the Blue Waters system. Calculations will provide nuclear properties of short-lived neutron-deficient and neutron-rich isotopes with little to no available experimental data that are expected to have a considerable impact on modeling X-ray burst observables, on triggering processes responsible for the synthesis of many of the heavy elements present in the universe, and on providing a stringent test of fundamental symmetries in nature and physics beyond the Standard model.