Effective-range corrections to the ground-state energy of the weakly-interacting Bose gas in two dimensions

TL;DR

This paper calculates the nonuniversal effective-range corrections to the ground-state energy of a weakly-interacting two-dimensional Bose gas using effective field theory and exact finite-system calculations, confirming the results through two methods.

Contribution

It introduces a combined approach of effective field theory and exact finite-system calculations to determine effective-range corrections in 2D Bose gases.

Findings

Effective-range corrections are quantified for 2D Bose gases.

Results are validated by both field theory and exact finite-system calculations.

The study enhances understanding of nonuniversal effects in low-dimensional quantum gases.

Abstract

Nonuniversal effects due to leading effective-range corrections are computed for the ground-state energy of the weakly-coupled repulsive Bose gas in two spatial dimensions. Using an effective field theory of contact interactions, these corrections are computed first by considering fluctuations around the mean-field free energy of a system of interacting bosons. This result is then confirmed by an exact calculation in which the energy of a finite number of bosons interacting in a square with period boundary conditions is computed and the thermodynamic limit is explicitly taken.