Functional renormalization for repulsive Bose-Bose mixtures at zero temperature

TL;DR

This paper applies the functional renormalization group to weakly-repulsive Bose-Bose mixtures at zero temperature, analyzing phase separation, density and spin fluctuations, and comparing results with perturbative methods.

Contribution

It introduces a FRG-based analysis of Bose-Bose mixtures, providing insights into phase separation and fluctuations beyond mean-field theory.

Findings

Phase separation occurs at the mean-field point.

FRG results agree with perturbative approaches for macroscopic properties.

Density and spin fluctuations significantly influence the system's behavior.

Abstract

We study weakly-repulsive Bose-Bose mixtures in two and three dimensions at zero temperature using the functional renormalization group (FRG). We examine the RG flows and the role of density and spin fluctuations. We study the condition for phase separation and find that this occurs at the mean-field point within the range of parameters explored. Finally, we examine the energy per particle and condensation depletion. We obtain that our FRG calculations compare favorably with known results from perturbative approaches for macroscopic properties.