Sufficient conditions for curvature invariants to avoid divergencies in Hyperextended Scalar Tensor theory for Bianchi models

TL;DR

This paper identifies conditions in Hyperextended Scalar Tensor theory that ensure curvature invariants remain finite, helping to avoid singularities in Bianchi cosmological models.

Contribution

It provides new classes of gravitation and coupling functions that prevent divergences in curvature invariants within Hyperextended Scalar Tensor theory for Bianchi models.

Findings

Identified conditions for bounded scalar curvature, Ricci, and Kretchmann scalars.

Derived classes of functions avoiding singularities in the models.

Compared results with previous work in Generalized Scalar Tensor theory.

Abstract

We look for sufficient conditions such that the scalar curvature, Ricci and Kretchmann scalars be bounded in Hyperextended Scalar Tensor theory for Bianchi models. We find classes of gravitation functions and Brans-Dicke coupling functions such that the theories thus defined avoid the singularity. We compare our results with these found by Rama in the framework of the Generalised Scalar Tensor theory for the FLRW models.