TY  - JOUR
A1  - Schmidt, Hans-Jürgen
T1  - Gauss-Bonnet lagrangian G lnG and cosmological exact solutions
T2  - Physical review : D, Particles, fields, gravitation, and cosmology
N2  - For the Lagrangian L = G lnG where G is the Gauss-Bonnet curvature scalar we deduce the field equation and solve it in closed form for 3-flat Friedmann models using a state-finder parametrization. Further we show that among all Lagrangians F(G) this L is the only one not having the form G(r) with a real constant r but possessing a scale-invariant field equation. This turns out to be one of its analogies to f(R) theories in two-dimensional space-time. In the appendix, we systematically list several formulas for the decomposition of the Riemann tensor in arbitrary dimensions n, which are applied in the main deduction for n = 4.
Y1  - 2011
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/36906
SN  - 1550-7998
VL  - 83
IS  - 8
PB  - American Physical Society
CY  - College Park
ER  -