Accelerating universe at early and late times in extended Jordan-Brans-Dicke gravity

TL;DR

This paper presents a unified model within extended Jordan-Brans-Dicke gravity that explains both early inflation and late-time dark energy using a two-field scalar potential, with implications for cosmic evolution and heating mechanisms.

Contribution

It introduces a two-field scalar potential model in extended Jordan-Brans-Dicke gravity that unifies early inflation and late dark energy phenomena.

Findings

A realistic inflation and dark energy scenario is achieved in a two-field model.

The model predicts efficient heating through parametric amplification during inflaton oscillations.

The universe approaches an asymptotic fixed point consistent with late-time acceleration.

Abstract

We propose a scenario that can explain the early-time inflation and the late-time dark energy within a unified framework. A scalar potential combining power-law and exponential type in a context of extended Jordan-Brans-Dicke gravity is critically important for this realization. A realistic scenario can be achieved in a two-field model in which one directional motion in field space realizes the slow-roll inflation. The inflaton ends up with oscillatory period and turns its direction to another direction that is identified as the quintessence field, giving rise to the dark energy at late times. The inflaton oscillation is expected to realize efficient heating if parametric amplification works. Along the quintessence direction, the present universe is on the way to reach the asymptotic fixed point. We search for successful parameter region, taking potential function in the form of low-order field powers times decreasing exponential in two dimensional field space.