Decoherence Problem in Ekpyrotic Phase

TL;DR

This paper investigates whether quantum decoherence leads to classical behavior during the ekpyrotic phase, finding that such a transition does not occur, which questions the classical interpretation of fluctuations in ekpyrotic models.

Contribution

It provides a simple model analysis showing that quantum decoherence does not occur during the ekpyrotic phase, challenging assumptions about classical fluctuations in such cosmological scenarios.

Findings

Quantum to classical transition does not happen during ekpyrosis.

Fluctuations remain quantum, not classical, during the ekpyrotic phase.

Implications for the scale-free power spectrum prediction in cyclic universe models.

Abstract

Quantum decoherence and the transition to semiclassical behavior during inflation has been extensively considered in the literature. In this paper, we use a simple model to analyze the same process in ekpyrosis. Our result is that the quantum to classical transition would not happen during an ekpyrotic phase even for superhorizon modes, and therefore the fluctuations cannot be interpreted as classical. This implies the prediction of scale-free power spectrum in ekpyrotic/cyclic universe model requires more inspection.