Non-oscillating Early Dark Energy and Quintessence from Alpha-Attractors

TL;DR

This paper introduces a non-oscillating scalar field model based on alpha-attractors that explains early dark energy and late-time dark energy without fine-tuning, addressing the Hubble tension more effectively.

Contribution

The authors propose a novel non-oscillating EDE model using alpha-attractors that naturally transitions from early to late dark energy without additional tuning.

Findings

The model injects EDE near matter-radiation equality.

It refreezes to become late-time dark energy at present.

The model's decay is faster than oscillatory EDE, improving observational fit.

Abstract

Early dark energy (EDE) is one of the most promising possibilities in order to resolve the Hubble tension: the discrepancy between early and late-Universe measurements of the Hubble constant. In this paper we propose a model of a scalar field which can explain both EDE and late Dark Energy (DE) in a joined manner without additional fine-tuning. The field features kinetic poles as with alpha-attractors. Our model provides an injection of EDE near matter-radiation equality, and redshifts away shortly after via free-fall, later refreezing to become late-time DE at the present day. Using reasonable estimates of the current constraints on EDE from the literature, we find that the parameter space is narrow but viable. As such our model is readily falsifiable. In contrast to other work in EDE, our model is non-oscillatory, which causes its decay to be faster than that of the usual oscillatory EDE, thereby achieving better agreement with observations.