Microscopic nuclear physics aims at describing structure and reaction properties of atomic nuclei starting from nucleonic scales and using the elementary interaction between nucleons as the basic input. Ab-initio methods use systematic interactions derived via effective theories of underlying Quantum Chromo-Dynamics and adjusted on properties of light systems. Most methods describing N interacting quantum bodies rely on the estimation of a wave function that is the solution of an N-body Schrödinger-type equation. Self-consistent Green’s function theory works differently, as it recasts the N-body problem by substituting suitably chosen Green’s functions for the wave function. An interesting aspect of Green’s function theory is that it involves a systematically improvable field – the self-energy – describing the interaction “felt” by the nucleon. This field, used in structure calculations, can thus also be used for describing nuclear reactions.
The PhD student will first study the formalism and learn how to use related tools, namely the spherical HFB code sPAN, which provides first-order contributions to the Green’s functions. The student will then implement second-order descriptions. Finally, the obtained self-energy will be used for nuclear reaction calculations, namely in the context of R-matrix theory. The latter is a convenient tool to describe (unbound) nucleons in the continuum, treating both the direct and exchange parts of the nucleon-nuclei interaction.