# Inflation and Bounce from Classical and Loop Quantum Cosmology Imperfect Fluids

## TL;DR

This paper explores how imperfect fluids with generalized equations of state can model inflationary and bouncing cosmologies in classical and loop quantum cosmology, comparing predictions with observational data.

## Contribution

It introduces a unified framework for modeling diverse cosmological scenarios using imperfect fluids and assesses their observational viability.

## Key findings

- Partial compatibility with Planck data achieved
- None of the scenarios fully agree with observational constraints
- Imperfect fluid models can realize various inflationary and bouncing scenarios

## Abstract

We investigate how various inflationary and bouncing cosmologies can be realized by imperfect fluids with a generalized equation of state, in the context of both classical and loop quantum cosmology. With regards to the inflationary cosmologies, we study the intermediate inflation scenario, the $R^2$ inflation scenario and two constant-roll inflation scenarios and with regards to the bouncing cosmologies we study the matter bounce scenario, the singular bounce and the super bounce scenario. Within the context of the classical cosmology, we calculate the spectral index of the power spectrum of primordial curvature perturbations, the scalar-to-tensor ratio and the running of the spectral index and we compare the resulting picture with the Planck data. As we demonstrate, partial compatibility with the observational data is achieved in the imperfect fluid description, however none of the above scenarios is in full agreement with data. This result shows that although it is possible to realize various cosmological scenarios using different theoretical frameworks, it is not guaranteed that all the theoretical descriptions are viable.