Collisional relaxation in diffuse clouds of trapped bosons

TL;DR

This paper investigates how collisions influence the damping and relaxation processes in a trapped Bose gas above the condensation temperature, using perturbative methods and variational principles.

Contribution

It introduces a perturbative approach to calculate relaxation rates in a trapped Bose gas, comparing results with experiments and prior theories.

Findings

Collision effects can be treated perturbatively in the collisionless regime.

Calculated relaxation rates agree with experimental data.

Theoretical framework improves understanding of damping in Bose gases.

Abstract

The damping of collective modes and the relaxation of temperature anisotropies in a trapped Bose gas is determined at temperatures above the Bose-Einstein condensation temperature in the collisionless regime. We demonstrate for both cases how the effects of collisions may be treated perturbatively and calculate relaxation rates based on a variational principle. Our results are compared with experiment and with previous theoretical calculations.