Kinetics of mobile impurities and correlation functions in one-dimensional superfluids at finite temperature

TL;DR

This paper investigates the limitations of hydrodynamics in 1D superfluids at finite temperature and introduces a kinetic approach based on mobile impurities to derive universal dynamical structure factors relevant to ultracold atom experiments.

Contribution

It develops a kinetic framework for fermionic quasiparticles as mobile impurities, extending the understanding of dynamical correlations beyond hydrodynamic validity.

Findings

Identifies the time scale { au} where hydrodynamics breaks down.

Derives universal dynamical structure factors for 1D superfluids.

Provides theoretical results applicable to ultracold atomic gas experiments.

Abstract

We scrutinize the hydrodynamic approach for calculating dynamical correlations in one-dimensional superfluids near integrability and calculate the characteristic time scale {\tau} beyond which this approach is valid. For time scales shorter than {\tau} hydrodynamics fails and we develop an approach based on kinetics of fermionic quasiparticles described as mobile impurities. New universal results for the dynamical structure factor relevant to experiments in ultracold atomic gases are obtained.