Born - Infeld-like modified gravity

TL;DR

This paper introduces a Born-Infeld-like modified gravity model with a specific function F(R), analyzing its theoretical properties, stability, and compatibility with local tests, and deriving solutions like Schwarzschild-de Sitter spacetime.

Contribution

The paper proposes a new F(R) gravity model inspired by Born-Infeld theory, analyzing its stability, solutions, and consistency with local gravitational tests.

Findings

The model reduces to Einstein-Hilbert action at small λ.

De Sitter space is unstable in this model.

Zero Ricci scalar solutions are stable and matter instability is absent.

Abstract

A modified theory of gravity with the function $F(R) = (1-\sqrt{1-2\lambda R})/\lambda$ is suggested and analyzed. At small value of the parameter $\lambda$ introduced the action is converted into Einstein$-$Hilbert action. The theory is consistent with local tests which gives a bound on the value of the parameter $\lambda\leq 2\times 10^{-6}$ cm$^2$. I have considered the Jordan frame as well as the Einstein frame in which the potential of the scalar field was obtained. The static Schwarzschild$-$de Sitter solutions of the model are obtained and analyzed. It was demonstrated that the de Sitter space is unstable but a solution with zero Ricci scalar is stable. It is shown that there is no matter instability in the proposed model.