Unified framework for early dark energy from α -attractors

TLDR: In this paper, the curvature of the potential in the early dark energy (EDE) model was analyzed for three representative cases and it was shown that the potential curvature in the EDE model is significantly larger than in other EDE models.

Abstract: One of the most appealing approaches to ease the Hubble tension is the inclusion of an early dark energy (EDE) component that adds energy to the Universe in a narrow redshift window around the time of recombination and dilutes faster than radiation afterwards. In this paper, we analyze EDE in the framework of $\ensuremath{\alpha}$-attractor models. As is well known, the success in alleviating the Hubble tension crucially depends on the shape of the energy injection. We show how different types of energy injections can be obtained, thanks to the freedom in choosing the functional form of the potential inspired by $\ensuremath{\alpha}$-attractor models. To confirm our intuition, we perform a Markov-chain Monte Carlo analysis for three representative cases and find indeed that ${H}_{0}$ is significantly larger than in $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$, like in other EDE models. Unlike axion-driven EDE models with a super-Planckian decay constant, the curvature of the potential in the EDE models required by the data is natural in the context of recent theoretical developments in $\ensuremath{\alpha}$-attractors.