Nuclear Theory from First Principles

Nuclear physics aims at understanding the emergence and properties of complex structures like atomic nuclei from QCD, the underlying theory of the strong interaction, and addresses some of the Big Science Questions including the origin of the elements, the limits of nuclear stability, searches for physics beyond the Standard Model and physics of neutron stars.

Answering these questions requires a reliable theoretical approach to nuclear structure and reactions.

Chiral effective field theory (EFT) combined with ab initio many-body methods provides an efficient and well-founded framework, and a major effort is needed to push the precision of nuclear forces and develop an efficient matching with the emerging lattice QCD results.Recently, the PI and his group made significant breakthroughs in the two-nucleon (2N) sector by developing chiral EFT interactions which are more precise than any other potentials and, for the first time, qualify to be regarded as partial wave analysis (PWA).

This shows that chiral EFT can, without any compromises on rigor and consistency, be advanced to a precision tool.

While the 2N sector can be considered as solved, three-nucleon (3N) scattering data could so far not be described showing that the simplest nuclear system beyond the 2N one is not understood.Given this success in the 2N sector, I propose to perform for the first time a PWA of 3N scattering and to determine the Hamiltonian complete up through fifth order.

The project aims at solving the long-standing 3N force challenge and development of accurate, state-of-the-art nuclear forces determined solely by the chiral symmetry of QCD and few-nucleon data. The resulting Hamiltonian will be used in large-scale ab initio calculations of nuclear structure and reactions.

We will also develop an efficient interface between lattice QCD and chiral EFT.

If successful, these studies will establish a rigorous, fully microscopic approach to nuclear physics firmly rooted in QCD.