Large scale effective theory for cosmological bounces

TL;DR

This paper presents an exactly solvable effective theory for cosmological bounces in loop quantum cosmology, providing analytical solutions and insights into the robustness and potential variability of bounce scenarios.

Contribution

It introduces a solvable bounce model serving as a perturbative basis for realistic scenarios and discusses how effective theories can incorporate complex quantum gravity effects.

Findings

Analytical bounce solutions derived in the model

Robustness of smooth bounces confirmed by simulations

Effective theory can include complex quantum effects

Abstract

An exactly solvable bounce model in loop quantum cosmology is identified which serves as a perturbative basis for realistic bounce scenarios. Its bouncing solutions are derived analytically, demonstrating why recent numerical simulations robustly led to smooth bounces under the assumption of semiclassicality. Several effects, easily included in a perturbative analysis, can however change this smoothness. The effective theory is not only applicable to such situations where numerical techniques become highly involved but also allows one to discuss conceptual issues. For instance, consequences of the notoriously difficult physical inner product can be implemented at the effective level. This indicates that even physical predictions from full quantum gravity can be obtained from perturbative effective equations.