%0 Journal Article
%T Conditions for the cosmological viability of f(R) dark energy models
%+ Laboratoire de Physique Théorique et Astroparticules (LPTA)
%A Amendola, L.
%A Gannouji, R.
%A Polarski, D.
%A Tsujikawa, S.
%Z 25 pages, 11 figures, version to appear in Physical Review D
%< avec comité de lecture
%@ 1550-7998
%J Physical Review D
%I American Physical Society
%V 75
%P 083504
%8 2007
%D 2007
%Z gr-qc/0612180
%Z 2006gr.qc....12180A
%R 10.1103/PhysRevD.75.083504
%K Phenomenology
%K High Energy Physics
%K Theory
%K General Relativity and Quantum Cosmology
%K Astrophysics
%Z Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]
%Z Physics [physics]/General Relativity and Quantum Cosmology [gr-qc]
%Z Physics [physics]/High Energy Physics - Phenomenology [hep-ph]
%Z Physics [physics]/High Energy Physics - Theory [hep-th]
%Z Sciences of the Universe [physics]/Astrophysics [astro-ph]Journal articles
%X We derive the conditions under which dark energy models whose Lagrangian densities f are written in terms of the Ricci scalar R are cosmologically viable. We show that the cosmological behavior of f(R) models can be understood by a geometrical approach consisting in studying the m(r) curve on the (r, m) plane, where m=Rf_{,RR}/f_{,R} and r=-Rf_{,R}/f with f_{,R}=df/dR. This allows us to classify the f(R) models into four general classes, depending on the existence of a standard matter epoch and on the final accelerated stage. The existence of a viable matter dominated epoch prior to a late-time acceleration requires that the variable m satisfies the conditions m(r) approx+0 and dm/dr>-1 at r approx-1. For the existence of a viable late-time acceleration we require instead either (i) m=-r-1, (sqrt{3}-1)/2
%G English
%L in2p3-00142912
%U https://hal.in2p3.fr/in2p3-00142912
%~ IN2P3
%~ LPTA
%~ CNRS
%~ UNIV-MONTP2
%~ UNIV-MONTPELLIER
%~ UM1-UM2