Energy spectrum and effective mass using a non-local 3-body interaction

TL;DR

This paper explores a nonlocal 3-body interaction model's impact on the energy spectrum and effective mass in Fermi gases and nuclear matter, revealing significant effects on effective mass predictions and implications for functional fitting.

Contribution

It introduces a nonlocal 3-body interaction consistent with Fock space, analyzing its effects on excitation spectra and effective mass in Fermi gases and nuclear matter.

Findings

Effective mass comparable to many-body perturbation theory in Fermi gas.

Large enhancement of effective mass in nuclear matter.

Implication that functionals should treat effective mass as a free parameter.

Abstract

We recently proposed a nonlocal form for the 3-body induced interaction that is consistent with the Fock space representation of interaction operators but leads to a fractional power dependence on the density. Here we examine the implications of the nonlocality for the excitation spectrum. In the two-component weakly interacting Fermi gas, we find that it gives an effective mass that is comparable to the one in many-body perturbation theory. Applying the interaction to nuclear matter, it predicts a large enhancement to the effective mass. Since the saturation of nuclear matter is partly due to the induced 3-body interaction, fitted functionals should treat the effective mass as a free parameter, unless the two- and three-body contributions are determined from basic theory.