Duration of classicality in highly degenerate interacting Bosonic systems

TL;DR

This paper investigates how highly occupied interacting bosonic systems behave classically only up to their relaxation time, with implications for axion cosmology, supported by analytical and numerical methods.

Contribution

It demonstrates that classical behavior in highly degenerate bosonic systems persists only up to the relaxation time, providing new insights into their temporal classicality limits.

Findings

Classical equations of motion hold only up to the relaxation time τ.

Numerical simulations confirm the analytical predictions.

Results are relevant for understanding axion and axion-like particle cosmology.

Abstract

We study sets of oscillators that have high quantum occupancy and that interact by exchanging quanta. It is shown by analytical arguments and numerical simulation that such systems obey classical equations of motion only on time scales of order their relaxation time $\tau$ and not longer than that. The results are relevant to the cosmology of axions and axion-like particles.