Extended $f(R,L_m)$ gravity with generalized scalar field and kinetic term dependences

TL;DR

This paper introduces a generalized $f(R,L_m, ext{scalar}, ext{kinetic})$ gravity model incorporating scalar fields and kinetic terms, aiming to better describe dark energy and dark matter interactions for cosmic acceleration.

Contribution

It develops a new gravitational framework with arbitrary functions of curvature, matter, scalar field, and kinetic terms, extending previous models and deriving corresponding field equations.

Findings

Derived gravitational field equations for the generalized model.

Explored models with nonminimal scalar-matter coupling.

Highlighted potential for explaining late-time cosmic acceleration.

Abstract

We generalize previous work by considering a novel gravitational model with an action given by an arbitrary function of the Ricci scalar, the matter Lagrangian density, a scalar field and a kinetic term constructed from the gradients of the scalar field, respectively. The gravitational field equations in the metric formalism are obtained, as well as the equations of motion for test particles, which follow from the covariant divergence of the stress-energy tensor. Specific models with a nonminimal coupling between the scalar field and the matter Lagrangian are further explored. We emphasize that these models are extremely useful for describing an interaction between dark energy and dark matter, and for explaining the late-time cosmic acceleration.