Dynamics of Brans-Dicke cosmology with varying mass fermions

TL;DR

This paper explores the cosmological behavior of Brans-Dicke theory with fermions that have variable mass and self-interactions, identifying conditions for stable, late-time accelerated expansion.

Contribution

It introduces a detailed analysis of fermion coupling and self-interactions in Brans-Dicke cosmology, revealing new stable solutions for late-time acceleration.

Findings

Stable late-time accelerated solutions identified.

Variable fermion mass cannot vanish during evolution.

Acceleration depends on fermion self-interaction for positive mbda. mbda

Abstract

In this paper, the cosmological dynamics of Brans-Dicke theory in which there are fermions with a coupling to BD scalar field as well as a self-interaction potential is investigated. The conditions that there exists a solution which is stable and represents a late-time accelerated expansion of the universe are found. The variable mass of fermions can not vanish exactly during the evolution of the universe once it exists initially. It is shown that the late-time acceleration depends completely on the self-interaction of the fermionic field if our investigation is restricted to the theory with positive BD parameter $\omega$. Provided a negative $\omega$ is allowed, there will be another two class of stable solutions describing late-time accelerated expansion of the universe.