Loop quantum cosmology and slow roll inflation

TL;DR

Loop quantum cosmology predicts a quantum bounce and super-inflation phase that naturally lead to conditions favoring slow roll inflation with over 68 e-foldings, unlike classical general relativity.

Contribution

This paper demonstrates that in LQC, the dynamics inherently favor slow roll inflation with sufficient e-foldings, without pre-big bang input, contrasting classical GR results.

Findings

Quantum bounce replaces big bang singularity.

Super-inflation phase leads to finite maximum Hubble parameter.

All trajectories naturally lead to conditions for sufficient slow roll inflation.

Abstract

In loop quantum cosmology (LQC) the big bang is replaced by a quantum bounce which is followed by a robust phase of super-inflation. Rather than growing unboundedly in the past, the Hubble parameter \emph{vanishes} at the bounce and attains a \emph{finite universal maximum} at the end of super-inflation. These novel features lead to an unforeseen implication: in presence of suitable potentials all LQC dynamical trajectories are funneled to conditions which virtually guarantee slow roll inflation with more than 68 e-foldings, {without any input from the pre-big bang regime}. This is in striking contrast to certain results in general relativity, where it is argued that the a priori probability of obtaining a slow roll with 68 or more e-foldings is suppressed by a factor $e^{-204}$.