# Big bounce and black bounce in quasi-topological gravity

## TL;DR

This paper introduces a quasi-topological gravity model that unifies cosmological and black hole bounce solutions, effectively avoiding singularities and linking loop quantum cosmology with higher-curvature gravity theories.

## Contribution

It proposes a novel covariant model in quasi-topological gravity that reproduces loop quantum cosmology dynamics and black bounce metrics, unifying quantum effects with higher-curvature corrections.

## Key findings

- Reproduces modified Friedmann equations from loop quantum cosmology
- Produces black bounce metrics similar to quantum Oppenheimer-Snyder model
- Resolves singularities in black hole and cosmological models

## Abstract

In the framework of quasi-topological (QT) gravity, we propose a novel model which is characterized by a bounce of the spacetime such that the singularity in standard general relativity can be avoided in both cosmological and black hole setups. Specifically, in the cosmological background, this model reproduces the modified Friedmann equation proposed in loop quantum cosmology, while in a black hole background, it produces a black bounce metric identical to that of the quantum Oppenheimer-Snyder (qOS) model. This model resolves the singularity presented in the qOS model as well as in QT gravity coupled to linear electromagnetic fields, and provides a unified, manifestly covariant framework for general spacetimes, from which both the modified Friedmann equation and the qOS black hole metric can be derived. Furthermore, it establishes a profound correspondence between the effective dynamics of loop quantum cosmology and the QT gravity theory, suggesting that certain quantum gravitational effects in loop quantum gravity can be captured by adding an infinite tower of higher-curvature corrections to the Einstein-Hilbert action.