String Inspired Quintom Model with Non-minimally Coupled Modified Gravity

TL;DR

This paper introduces a quintom dark energy model with non-minimal coupling to modified gravity, inspired by string theory, demonstrating EoS crossing -1 without higher derivative operators.

Contribution

It presents a novel quintom model with non-minimal coupling to f(R) gravity, avoiding the need for higher derivative terms to achieve EoS crossing -1.

Findings

EoS parameter crosses -1 without higher derivatives

Derived conditions for model parameters to enable crossing

Model consistent with string-inspired tachyonic Lagrangian

Abstract

In this paper we consider a quintom model of dark energy with non-minimal coupling between scalar field and modified gravity which is known $f(R)$ gravity. The Lagrangian for scalar field has been inspired by tachyonic Lagrangian in string theory. Then we obtain the equation of state (EoS), and the condition required for the model parameters when $\omega$ crosses over -1. This model shows that for having $\omega$ across over -1, one doesn't need to add some higher derivative operator in the tachyonic part of action (the way that usually used to obtain crossing of the phantom divide line for EoS parameter).