A Cosmological Model with Fermionic Field and Gauss-Bonnet Term

TL;DR

This paper explores a string theory-inspired cosmological model where a Gauss-Bonnet term coupled with a fermionic field influences universe acceleration, showing both early deceleration and late acceleration with stable equation-of-state behavior.

Contribution

It introduces a novel coupling between the Gauss-Bonnet term and a non-Dirac fermionic field, affecting cosmic acceleration phases.

Findings

Gauss-Bonnet-fermion coupling induces late-time acceleration.

The model predicts an early decelerating universe phase.

The equation-of-state parameter remains stable, ensuring theoretical consistency.

Abstract

In this work, a cosmological model inspired by string theory with Gauss-Bonnet term coupled to the fermionic field is taken into consideration. The self-interaction potential is considered as a combination of the scalar and pseudo-scalar invariants. Here the cosmological contribution of the coupling of Gauss-Bonnet term with a non-Dirac fermionic field--characterized by an \textit{interaction term}$L_{DG} ^2$-- is investigated. It is observed that the new type of coupling plays a significant role in the accelerating behavior of the universe. Specifically, in addition to the late time acceleration for the universe, $L_{DG} ^2$ produces an early decelerating behavior. The behavior of the equation-of-state parameter $(w)$ is such that it guarantees the stability of the theory.