Cosmology and stability in scalar tensor bigravity with non-minimal kinetic coupling gravity

TL;DR

This paper extends scalar tensor bigravity models by incorporating non-minimal kinetic couplings to Einstein tensors, demonstrating their ability to explain various expanding universes and analyzing the stability of these solutions.

Contribution

It introduces a generalized bigravity model with non-minimal kinetic couplings and investigates the stability of its cosmological solutions.

Findings

A broad class of expanding universe solutions is explained.

Stable solutions are identified through perturbation analysis.

The model provides a viable framework for cosmological evolution.

Abstract

We generalize the scalar tensor bigravity models to the non-minimal kinetic coupling scalar tensor bigravity models with two scalar fields whose kinetic terms are non-minimally coupled to two Einstein tensors constructed by two metrics. We show that a broad class of expanding universes can be explained by some solutions of this model. Then, we study the stability issue of the solutions by means of imposing homogeneous perturbation on the equations of motion and extract the stable solutions.