scholarly journals Generalized energy-momentum-squared gravity in the Palatini formalism

2020 ◽  
Vol 102 (6) ◽  
Author(s):  
Elham Nazari ◽  
Farahnaz Sarvi ◽  
Mahmood Roshan
Keyword(s):  
Palatini Formalism

scholarly journals GENERALIZED EINSTEIN–MAXWELL FIELD EQUATIONS IN THE PALATINI FORMALISM

2013 ◽  
Vol 22 (04) ◽  
pp. 1350017 ◽  
Author(s):  
GINÉS R. PÉREZ TERUEL
Keyword(s):  
Electromagnetic Field ◽  
Algebraic Equation ◽  
Ricci Tensor ◽  
Maxwell Equations ◽  
Natural Generalization ◽  
New Method ◽  
Maxwell Field ◽  
Field Equations ◽  
Palatini Formalism

We derive a new set of field equations within the framework of the Palatini formalism. These equations are a natural generalization of the Einstein–Maxwell equations which arise by adding a function [Formula: see text], with [Formula: see text] to the Palatini Lagrangian f(R, Q). The result we obtain can be viewed as the coupling of gravity with a nonlinear extension of the electromagnetic field. In addition, a new method is introduced to solve the algebraic equation associated to the Ricci tensor.

scholarly journals Constraining f ( R ) gravity in the Palatini formalism

2006 ◽  
Vol 23 (4) ◽  
pp. 1253-1267 ◽  
Author(s):  
Thomas P Sotiriou
Keyword(s):  
Palatini Formalism

scholarly journals Bianchi I and V cosmologies with Hu-Sawicki f(R) gravity in Palatini formalism

2018 ◽  
Vol 2 (11) ◽  
pp. 115017
Author(s):  
Debika K Banik ◽  
Sebika K Banik ◽  
Kalyan Bhuyan
Keyword(s):  
Palatini Formalism ◽  
Bianchi I

FURTHER EXTENDED THEORIES OF GRAVITATION: PART I

2010 ◽  
Vol 07 (05) ◽  
pp. 887-898 ◽  
Author(s):  
M. DI MAURO ◽  
L. FATIBENE ◽  
M. FERRARIS ◽  
M. FRANCAVIGLIA
Keyword(s):  
Forthcoming Paper ◽  
Palatini Formalism ◽  
Extended Theories ◽  
Theories Of Gravitation

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 behaviors even compared to f(R) theories.

scholarly journals General Slow-Roll Inflation in f(R) Gravity under the Palatini Approach

Symmetry ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1958
Author(s):  
Sabit Bekov ◽  
Kairat Myrzakulov ◽  
Ratbay Myrzakulov ◽  
Diego Sáez-Chillón Gómez
Keyword(s):  
Scalar Field ◽  
Simple Model ◽  
Spectral Index ◽  
Effective Potential ◽  
Modified Gravity ◽  
Palatini Formalism ◽  
Slow Roll ◽  
Slow Roll Inflation

Slow-roll inflation is analyzed in the context of modified gravity within the Palatini formalism. As shown in the literature, inflation in this framework requires the presence of non-traceless matter; otherwise, it does not occur just as a consequence of the nonlinear gravitational terms of the action. Nevertheless, by including a single scalar field that plays the role of the inflaton, slow-roll inflation can be performed in these theories, where the equations lead to an effective potential that modifies the dynamics. We obtain the general slow-roll parameters and analyze a simple model to illustrate the differences introduced by the gravitational terms under the Palatini approach, and the modifications on the spectral index and the tensor to scalar ratio predicted by the model.

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