Quantum Many-Body Theories for the Nuclear Equation of State

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An overarching challenge in nuclear theory is to develop a predictive framework for atomic nuclei and the extended nuclear matter found in the interiors of stars and other dense astrophysical environments, starting from the fundamental interactions between the constituent nucleons and solving the quantum mechanical equations of motion that describe their dynamics. This project focuses on developing new theoretical techniques to predict the behavior of extended nuclear matter under a wide range of conditions such as those found in the interiors of stars. Mapping out the behavior of nuclear matter as a function of asymmetry (i.e., different ratios of protons and neutrons), density, and temperature is referred to as constructing the nuclear equation of state. The project will generalize techniques which have previously been used to describe the properties of atomic nuclei at zero temperature to the problem of extended nuclear matter (i.e., homogenous systems comprised of an infinite number of nucleons) at finite temperatures, in order to construct the nuclear equation of state. The project develops and applies microscopic many-body methods targeted for dense nuclear matter, with extensions to access finite temperature and dynamic response properties. The research is built around modern many-body methods such as coupled cluster theory and the in-medium similarity renormalization group. In addition to extending nuclear matter calculations to finite temperature and dynamic response properties, powerful techniques from machine learning and dynamical systems are used to develop fast and accurate emulators of our many-body calculations, which is necessary for computationally-intensive uncertainty quantification studies. Additionally, renormalization group scale and scheme dependence of operators that couple to external probes are studied to better understand how reaction theory and structure theory calculations can be carried out in a consistent framework.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.