The $s$-wave scattering length of a Gaussian potential

TL;DR

This paper derives accurate analytical formulas for the s-wave scattering length of a Gaussian potential in various dimensions, improving the description of ultracold atomic gases across different interaction regimes.

Contribution

It introduces simple analytical expressions for the s-wave scattering length that are accurate near bound states and across wide parameter regimes, enhancing previous numerical methods.

Findings

Derived analytical formulas match numerical results closely.

Formulas accurately describe scattering length near bound state formation.

Provides a hierarchy of approximations for different accuracy levels.

Abstract

We provide accurate expressions for the $s$-wave scattering length for a Gaussian potential well in one, two and three spatial dimensions. The Gaussian potential is widely used as a pseudopotential in the theoretical description of ultracold atomic gases, where the $s$-wave scattering length is a physically relevant parameter. We first describe a numerical procedure to compute the value of the $s$-wave scattering length from the parameters of the Gaussian but find that its accuracy is limited in the vicinity of singularities that result from the formation of new bound states. We then derive simple analytical expressions that capture the correct asymptotic behavior of the $s$-wave scattering length near the bound states. Expressions that are increasingly accurate in wide parameter regimes are found by a hierarchy of approximations that capture an increasing number of bound states. The small number of numerical coefficients that enter these expressions is determined from accurate numerical calculations. The approximate formulas combine the advantages of the numerical and approximate expressions, yielding an accurate and simple description from the weakly to the strongly interacting limit.