Coupling constant constraints in a nonminimally coupled phantom cosmology

TL;DR

This paper constrains the coupling constant in a nonminimally coupled phantom cosmology model using various observational data, providing bounds that relate to the Equivalence Principle.

Contribution

It offers the first comprehensive observational constraint on the coupling parameter in nonminimally coupled phantom scalar field models.

Findings

The coupling constant $\xi$ is close to the conformal coupling value.

Observational data favor a small deviation from conformal coupling.

The results imply an indirect bound on the Equivalence Principle.

Abstract

In the paper we investigate observational constraints on coupling to gravity constant parameter $\xi$ using distant supernovae SNIa data, baryon oscillation peak (BOP), the cosmic microwave background radiation (CMBR) shift parameter, and $H(z)$ data set. We estimate the value of this parameter to constrain the extended quintessence models with nonminimally coupled to gravity phantom scalar field. The combined analysis of observational data favors a value of $\xi$ which lies in close neighborhood of the conformal coupling. While our estimations are model dependent they give rise to a indirect bound on the Equivalence Principle.