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

Jerry Draayer, Louisiana State University

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Jerry Draayer, Tomas Dytrych, Kristina Launey, Daniel Langr, Tomas Oberhuber, Robert Baker, Bei Wang, Grigor Sargsyan, Vit Hanousek, Pavel Novy

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 Blue Waters. 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 using 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 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.