# Condensation and superfluidity of dilute Bose gases with finite-range interaction

## TL;DR

This paper studies how finite-range interactions affect the properties of dilute Bose gases, revealing modifications to superfluidity and symmetry breaking using an effective-field-theory approach.

## Contribution

It introduces a finite-range interaction model for dilute Bose gases and develops a perturbative scheme incorporating quantum and thermal fluctuations.

## Key findings

- Finite-range corrections influence superfluid density.
- Relation between symmetry breaking and superfluidity is clarified.
- Landau's equation is recovered with finite-range effects.

## Abstract

We investigate an ultracold and dilute Bose gas by taking into account a finite-range two-body interaction. The coupling constants of the resulting Lagrangian density are related to measurable scattering parameters by following the effective-field-theory approach. A perturbative scheme is then developed up to the Gaussian level, where both quantum and thermal fluctuations are crucially affected by finite-range corrections. In particular, the relation between spontaneous symmetry breaking and the onset of superfluidity is emphasized by recovering the renowned Landau's equation for the superfluid density in terms of the condensate one.