Further Extended Theories of Gravitation: Part I

TL;DR

This paper introduces a broad class of relativistic gravitational theories based on the EPS framework, encompassing all Palatini f(R) theories and highlighting their exotic behaviors compared to standard models.

Contribution

It defines a new unified class of extended gravitational theories within the EPS framework, including all Palatini f(R) theories and suggesting further generalizations.

Findings

Class of relativistic gravitation theories proposed

All Palatini f(R) theories are included in this class

Exotic behaviors observed in these models

Abstract

We shall here propose a class of relativistic theories of gravitation, based on a foundational paper of Ehlers Pirani and Schild (EPS).All "extended theories of gravitation" (also known as f(R) theories) in Palatini formalism are shown to belong to this class. In a forthcoming paper we shall show that this class of theories contains other more general examples. EPS framework helps in the interpretation and solution of these models that however have exotic behaviours even compared to f(R) theories.