Five-dimensional Einstein-Chern-Simons cosmology

We consider a five-dimensional Einstein-Chern-Simons action which is composed of a gravitational sector and a sector of matter, where the gravitational sector is given by a Chern-Simons gravity action instead of the Einstein-Hilbert action, and where the matter sector is given by a perfect fluid. The gravitational Lagrangian is obtained gauging some Lie-algebras, which in turn, were obtained by S-expansion procedure of anti–de Sitter and de Sitter algebras. On the cosmological plane, we discuss the field equations resulting from the anti–de Sitter and de Sitter frameworks and we show analogies with four-dimensional cosmological schemes.

Figure 1

The Hubble parameter for $\omega =-1/2$. Here, $A=0.5$ (blue line) and $A=3$ (red line). The 4D-case is the black line.

Figure 2

The deceleration parameter for $\omega =-1/2$. Note that $q=0$ is recovered when $z\to \infty$. Here, $A=0.5$ (blue line) and $A=1.5$ (red line).