f(R) Cosmology in the First Order Formalism

In the present work we consider those theories that are obtained from a Lagrangian density ℒ<sub>T</sub>(R) = f(R)√-g + ℒ<sub>M</sub>, that depends on the curvature scalar and a matter Lagrangian that does not depend on the connection, and apply Palatini's method to obta...

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Autores principales: Barraco, Daniel E., Hamity, Víctor Hugo, Vucetich, Héctor
Formato: Articulo
Lenguaje:Inglés
Publicado: 2002
Materias:
Astronomía
cosmology
non-linear Lagrangian
Palatini approach
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/141452
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-141452
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Astronomía
cosmology
non-linear Lagrangian
Palatini approach
spellingShingle Astronomía
cosmology
non-linear Lagrangian
Palatini approach
Barraco, Daniel E.
Hamity, Víctor Hugo
Vucetich, Héctor
f(R) Cosmology in the First Order Formalism
topic_facet Astronomía
cosmology
non-linear Lagrangian
Palatini approach
description In the present work we consider those theories that are obtained from a Lagrangian density ℒ<sub>T</sub>(R) = f(R)√-g + ℒ<sub>M</sub>, that depends on the curvature scalar and a matter Lagrangian that does not depend on the connection, and apply Palatini's method to obtain the field equations. We start with a brief discussion of the field equations of the theory and apply them to a cosmological model described by the FRW metric. Then, we introduce an auxiliary metric to put the resultant equations into the form of GR with cosmological constant and coupling constant that are curvature depending. We show that we reproduce known results for the quadratic case. We find relations among the present values of the cosmological parameters q₀, H₀, (G◦/G)₀ and (G◦◦/G)₀. Next we use a simple perturbation scheme to find the departure in angular diameter distance with respect to General Relativity. Finally, we use the observational data to estimate the order of magnitude of what is essentially the departure of f(R) from linearity. The bound that we find for f''(0) is so huge that permit almost any f(R). This is in the nature of things: the effect of higher order terms in f(R) are strongly suppressed by power of Planck's time 8πG₀. In order to improve these bounds more research on mathematical aspects of these theories and experimental consequences is necessary.
format Articulo
Articulo
author Barraco, Daniel E.
Hamity, Víctor Hugo
Vucetich, Héctor
author_facet Barraco, Daniel E.
Hamity, Víctor Hugo
Vucetich, Héctor
author_sort Barraco, Daniel E.
title f(R) Cosmology in the First Order Formalism
title_short f(R) Cosmology in the First Order Formalism
title_full f(R) Cosmology in the First Order Formalism
title_fullStr f(R) Cosmology in the First Order Formalism
title_full_unstemmed f(R) Cosmology in the First Order Formalism
title_sort f(r) cosmology in the first order formalism
publishDate 2002
url http://sedici.unlp.edu.ar/handle/10915/141452
work_keys_str_mv AT barracodaniele frcosmologyinthefirstorderformalism
AT hamityvictorhugo frcosmologyinthefirstorderformalism
AT vucetichhector frcosmologyinthefirstorderformalism
bdutipo_str Repositorios
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