Onset of classical behaviour after a phase transition

TL;DR

This paper investigates how classical behavior emerges in a scalar field after a phase transition, focusing on decoherence caused by interactions with environmental modes, and finds that decoherence occurs rapidly compared to other dynamics.

Contribution

It provides a detailed calculation of decoherence time in a scalar field model post-phase transition, highlighting the role of environmental interactions in classicalization.

Findings

Decoherence time is generally the shortest dynamical timescale.

Diagonalisation of the decoherence functional confirms rapid classical behavior onset.

Additional environmental fields accelerate the decoherence process.

Abstract

We analyze the onset of classical behaviour in a scalar field after a continuous phase transition, in which the system-field, the long wavelength order parameter of the model, interacts with an environment of its own short-wavelength modes. We compute the decoherence time for the system-field modes from the master equation and compare it with the other time scales of the model. Within our approximations the decoherence time is in general the smallest dynamical time scale. Demanding diagonalisation of the decoherence functional produces identical results. The inclusion of other environmental fields makes diagonalisation occur even earlier.