Frontiers in Nuclear Physics

Coordinators: Barry Holstein, Wick Haxton, and Martin Savage

Scientific Advisors: Silas Beane, Evgeny Epelbaum, Dean Lee, and Andreas Wirzba

Nuclear Physics is entering a new era. With the rapidly increasing capabilities of lattice gauge theory to perform ab initio calculations in Quantum Chromodynamics (QCD) and chiral effective field theory (EFT) techniques that systematize the nuclear forces and allow for precise simulations of atomic nuclei, we are beginning to understand how nuclei and the nuclear forces emerge from QCD. This progress is complemented by a broad and vigorous experimental program. Consequently, answers to fundamental questions at the heart of nuclear physics that could not be addressed before, or required sophisticated modeling, are nearly within our grasp. 

These new capabilities permit refined calculations of the properties and reactions of nuclei, of nuclear matter under extreme conditions such as occurs in the interior of neutron stars, and of the nuclei used in tests of the Standard Model. They also provide insights into the environmental selection of fundamental parameters such as the Higgs vacuum expectation value, the quark masses, the fine-structure constant and nuclear properties relevant to nucleosynthesis. This program will advance the physics of strongly interacting systems while impacting our understanding of the physics of nuclei and their role in making up the observed matter of the Universe. 

Key questions to be addressed in this program are:

1. What is the best path forward to refine the nuclear forces, the structure and interactions of nuclei and provide fundamental insights into nuclear physics directly from QCD?

2. Can successful, but model dependent, many-body methods, such as density functional approaches, be transformed into predictive EFTs, allowing for model-independent investigations of the limits of nuclear stability?

3. Nuclei continue to be used as laboratories for precision tests of the standard model of particle physics and in searches for physics that may exist beyond the standard model. What are the quantities that are best suited to make progress addressing fundamental physics questions?  How far can both theory and experiment be pushed in setting limits on electric dipole moments of nucleons and light nuclei to reveal the sources of CP violation? What are the present uncertainties in nuclear matrix elements relevant for dark matter searches and double beta decay, and how can they be improved? How do nuclei interact with neutrinos in the GeV energy regime and how can calculations of these interaction cross sections be improved?

4. How do these developing capabilities complement the international experimental programs that study QCD in depth, explore nuclei at the limits of stability and search for neutrinoless double-beta decay?