Ground state energy of a dilute inhomogeneous Fermi gas

TL;DR

This paper rigorously analyzes the ground state energy of a large, dilute, inhomogeneous Fermi gas, demonstrating convergence to the Thomas-Fermi energy with interaction corrections involving the scattering length.

Contribution

It provides a mathematical proof of the energy convergence for a dilute inhomogeneous Fermi gas, combining upper and lower bounds using semi-classical analysis and the Dyson lemma.

Findings

Energy per particle converges to the Thomas-Fermi energy.

Interaction effects are captured by the scattering length.

The proof employs a novel combination of bounds and regularization techniques.

Abstract

We study the ground state energy of a system of N fermions with two spin states in the large N limit. The particles are placed in an inhomogeneous trapping potential and interact via scaled interactions. We study a dilute limit where the range of the interaction potential is much smaller than the typical inter-particle distance. We show that the energy per particle converges to the Thomas-Fermi energy of the system, with a perturbative term corresponding tot he interaction and exhibiting the scattering length of the potential. The proof is decomposed into two bounds. First, we construct an appropriate test-state to prove the upper bound. Then, we prove the lower bound by the Dyson lemma, which allows us to regularize the interaction potential, and several semi-classical tools.