RT Journal Article
T1 On the non-attractive character of gravity in f(R) theories
A1 Albareti, F. D.
A1 Ruiz Cembranos, José Alberto
A1 Cruz Dombriz, Álvaro de la
A1 Dobado González, Antonio
AB Raychaudhuri equation is found provided that particular energy conditions are assumed and regardless the considered solution of the Einstein's equations. This fact is usually interpreted as a manifestation of the attractive character of gravity. Nevertheless, a positive contribution to Raychaudhuri equation from space-time geometry should occur since this is the case in an accelerated expanding Robertson-Walker model for congruences followed by fundamental observers. Modified gravity theories provide the possibility of a positive contribution although the standard energy conditions are assumed. We address this important issue in the context of f(R) theories, deriving explicit upper bounds for the contribution of space-time geometry to the Raychaudhuri equation. Then, we examine the parameter constraints for some paradigmatic f(R) models in order to ensure a positive contribution to this equation. Furthermore, we consider the implications of these upper bounds in the equivalent formulation of f(R) theories as a Brans-Dicke model.
PB Iop Publishing Ltd
SN 1475-7516
YR 2013
FD 2013-07
LK https://hdl.handle.net/20.500.14352/33349
UL https://hdl.handle.net/20.500.14352/33349
LA eng
NO ©2013 IOP Publishing Ltd and Sissa Medialab srlThis work has been supported by MINECO (Spain) project numbers FIS2011-23000, FPA2011-27853-C02-01 and Consolider-Ingenio MULTIDARK CSD2009-00064. AdlCD also acknowledges financial support from Marie Curie - Beatriu de Pinós contract BP-B00195, Generalitat de Catalunya and ACGC, University of Cape Town.
NO MINECO (Spain)
NO Consolider-Ingenio MULTIDARK
NO Marie Curie - Beatriu de Pinos
NO Generalitat de Catalunya
NO ACGC, University of Cape Town
DS Docta Complutense
RD 7 abr 2025