Stable exponential cosmological solutions with zero variation of G and three different Hubble-like parameters in the Einstein–Gauss–Bonnet model with a Λ -term

We consider a D-dimensional gravitational model with a Gauss–Bonnet term and the cosmological term Λ. We restrict the metrics to diagonal cosmological ones and find for certain Λ a class of solutions with exponential time dependence of three scale factors, governed by three non-coinciding Hubble-like parameters H> 0 , h1 and h2, corresponding to factor spaces of dimensions m> 2 , k1> 1 and k2> 1 , respectively, with k1≠ k2 and D= 1 + m+ k1+ k2. Any of these solutions describes an exponential expansion of 3d subspace with Hubble parameter H and zero variation of the effective gravitational constant G. We prove the stability of these solutions in a class of cosmological solutions with diagonal metrics. © 2017, The Author(s).