Speaker
Description
We consider a $D$-dimensional Einstein-Gauss-Bonnet model with a cosmological term $\Lambda$ and two non-zero
constants: $\alpha_1$ and $\alpha_2$. We restrict the metrics to be diagonal ones and study a class of solutions
with exponential time dependence of three scale factors, governed by three non-coinciding Hubble-like parameters:
$H \neq 0$, $h_1$ and $h_2$, obeying to $m H + k_1 h_1 + k_2 h_2 \neq 0$ and corresponding to factor spaces of
dimensions $m > 1$, $k_1 > 1$ and $k_2 > 1$, respectively ($D = 1 + m + k_1 + k_2$). We analyse two cases:
i) $m < k_1 < k_2$ and ii) $1< k_1 = k_2 = k$, $k \neq m$. We show that in both cases the solutions exist if
$\alpha = \alpha_2 / \alpha_1 > 0$ and $\alpha \Lambda > 0$ obeys certain restrictions, e.g. upper and lower
bounds. In case ii) explicit relations for exact solutions are found. In both cases the subclasses of stable
and non-stable solutions are singled out. For $m >2$ the case i) contains a subclass of solutions describing
an exponential expansion of $3$-dimensional subspace with Hubble parameter $H > 0$ and zero variation of the effective gravitational constant $G$.
