WoU-MMA: Thermodynamics of Nuclei and Nuclear Matter

University Of North Carolina At Chapel Hill, Chapel Hill NC

Investigators

Abstract

The origin of the heavy elements in our Universe remains a mystery. At least half of those elements are believed to be generated in violent collisions between neutron stars, and whether this is true is a central question in nuclear astrophysics. To answer that question, neutron-star collisions are studied in astrophysics simulations, which in turn need input data from nuclear physics. Specifically, simulations require information about neutrons and protons at very high temperatures and densities. This project aims to calculate such thermal properties from first principles: starting from neutrons and protons and their interactions, and implementing the computational machinery of lattice quantum field theory. Using the same tools, the PI will also study simpler, related systems in ultracold atomic physics that are currently realized in many laboratories worldwide. The PI will mentor graduate students engaged in this research in a teaching-and-training collaboration with UNC-Pembroke, and in research collaborations with Michigan State University, the University of Washington, and TU Darmstadt. Outreach activities will also include the organization of the 21st International Conference on Recent Progress in Many-Body Theories at UNC-CH. The recent gravitational- and electromagnetic-wave detection of neutron star mergers has given new impetus to the ab initio characterization of the thermodynamics of nuclei and nuclear matter. The latter are required as input to dynamical astrophysics simulations but pose a challenging quantum many-body problem. The overarching objective of this project is to face that challenge, starting with the finite-temperature thermodynamics of neutron matter, using the ab initio non-perturbative tools of non-relativistic lattice field theory combined with chiral effective theory interactions. The research program will focus on the thermal equation of state of nuclear matter, beginning with dilute pure neutron matter, with plans to include protons at a later stage. Calculations of the pairing, superfluidity, and clustering properties of neutron matter are also planned, as they impact the structure and thermal evolution of neutron stars. This project will also pursue studies of nucleon clustering and the density of states of finite nuclei, and ab initio calculations of the neutron skin, all of which are relevant to nuclear astrophysics and the physics of neutron-rich nuclei to be realized in heavy-ion facilities around the world. This project advances the objectives of "Windows on the Universe: the Era of Multi-Messenger Astrophysics", one of the 10 Big Ideas for Future NSF Investments. 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.