Dynamics and kinetics of quasiparticle decay in a nearly-one-dimensional degenerate Bose gas

TL;DR

This paper investigates how quasiparticles decay in a nearly-one-dimensional Bose gas, revealing that virtual transverse excitations lead to effective three-body collisions causing diffusive quasiparticle dynamics.

Contribution

It provides a calculation of the matrix element for three-body quasiparticle scattering in a nearly-1D Bose gas, highlighting the role of virtual transverse modes in decay processes.

Findings

Decay involves effective three-body elastic collisions.

Low-frequency, thermally populated modes induce diffusive quasiparticle behavior.

Breakdown of 1D integrability affects quasiparticle dynamics.

Abstract

We consider decay of a quasiparticle in a nearly-one-dimensional quasicondensate of trapped atoms, where virtual excitations of transverse modes break down one-dimensionality and integrability, giving rise to effective three-body elastic collisions. We calculate the matrix element for the process that involves one incoming quasiparticle and three outgoing quasiparticles. Scattering that involves low-frequency modes with high thermal population results in a diffusive dynamics of a bunch of quasiparticles created in the system.