General Einstein-Cartan quadratic gravity with derivative couplings

TL;DR

This paper explores a generalized Einstein-Cartan gravity model with quadratic curvature terms and derivative couplings, deriving its effective metric theory, analyzing its inflationary dynamics, and showing compatibility with current observational data.

Contribution

It introduces a new Einstein-Cartan quadratic gravity model with derivative couplings and derives its effective metric theory with a dynamical pseudoscalar field.

Findings

The model evolves into an effective single-field inflationary scenario.

It is consistent with latest observational data across a range of parameters.

Upper limits on derivative coupling parameters are established.

Abstract

Within the framework of Einstein-Cartan gravity we consider an action, containing up to quadratic terms of the Ricci scalar and the Holst invariant, coupled non-minimally to a scalar field, including couplings of its derivatives to curvature. We derive the equivalent metric theory, featuring an extra dynamical pseudoscalar degree of freedom associated with the presence of the Holst term in the action. We study the evolution of the resulting two-field system in a FRW background and show that it evolves rapidly into an effective single-field inflationary model. We find that the model is consistent with the latest observational data for a wide range of its parameters, determining the necessary upper limits on derivative coupling parameters.