Quintessence without scalar fields

TL;DR

This paper explores alternative theories to scalar fields for explaining cosmic acceleration, focusing on effective models derived from fundamental physics like extended gravity theories and generalized matter equations.

Contribution

It introduces and compares new approaches to quintessence that do not rely on scalar fields, including higher order curvature, torsion, and Van der Waals corrections.

Findings

Exact accelerated solutions are achievable in these models.

Models with higher order curvature and torsion can produce cosmic acceleration.

Generalized matter equations can also lead to accelerated expansion.

Abstract

The issues of quintessence and cosmic acceleration can be discussed in the framework of theories which do not include necessarily scalar fields. It is possible to define pressure and energy density for new components considering effective theories derived from fundamental physics like the extended theories of gravity or simply generalizing the state equation of matter. Exact accelerated expanding solutions can be achieved in several schemes: either in models containing higher order curvature and torsion terms or in models where the state equation of matter is corrected by a second order Van der Waals terms. In this review, we present such new approaches and compare them with observations.