Cuscuton-like contribution to dark energy evolution

TL;DR

This paper investigates how a cuscuton-like term influences dark energy evolution, providing analytical solutions, exploring its effects on cosmic history, and statistically comparing it with the standard Lambda-CDM model, finding strong support for the new model.

Contribution

It introduces a first-order Hamilton-Jacobi-like framework to analyze cuscuton effects on dark energy and compares its viability with Lambda-CDM using observational data.

Findings

Cuscuton-like contribution can modify cosmic evolution and alter expansion phases.

Analytical solutions for dark energy dynamics with cuscuton are derived.

Statistical analysis favors the cuscuton model over Lambda-CDM based on AIC.

Abstract

This work deals with the presence of the cuscuton term in the otherwise standard dark energy evolution under the usual FLRW background. We disclose a first-order framework similar to the Hamilton-Jacobi formalism, which helps us to solve the equations of motion and find analytical solutions. We explore several possibilities, concentrating mainly on how the cuscuton-like contribution works to modify cosmic evolution. Some results are of current interest since they describe scenarios capable of changing the evolution, adding or excluding possible distinct phases during the Universe's expansion history. Additionally, we present interesting constraints on the cuscuton-like contribution for the dark energy evolution using a set of homogeneous geometrical observational probes. Finally, based on the Akaike Information Criterion (AIC), we perform a statistical comparison of the cuscuton-like model with $\Lambda$CDM, and find strong support for our model.