TY  - JOUR
AU  - Barragan, C.
AU  - Olmo, G. J.
PY  - 2010
DA  - 2010//
TI  - Isotropic and anisotropic bouncing cosmologies in Palatini gravity
T2  - Phys. Rev. D
JO  - Physical Review D
SP  - 084015
EP  - 15pp
VL  - 82
IS  - 8
PB  - Amer Physical Soc
AB  - We study isotropic and anisotropic (Bianchi I) cosmologies in Palatini f(R) and f(R, R μnu R μnu) theories of gravity with a perfect fluid and consider the existence of nonsingular bouncing solutions in the early universe. We find that all f(R) models with isotropic bouncing solutions develop shear singularities in the anisotropic case. On the contrary, the simple quadratic model R + aR(2)/R-P + R μnu R μnu/R-P exhibits regular bouncing solutions in both isotropic and anisotropic cases for a wide range of equations of state, including dust (for a<0) and radiation (for arbitrary a). It thus represents a purely gravitational solution to the big bang singularity and anisotropy problems of general relativity without the need for exotic (w>1) sources of matter/energy or extra degrees of freedom.
SN  - 1550-7998
UR  - http://arxiv.org/abs/1005.4136
UR  - https://doi.org/10.1103/PhysRevD.82.084015
DO  - 10.1103/PhysRevD.82.084015
LA  - English
N1  - ISI:000282751900002
ID  - Barragan+Olmo2010
ER  -