Exponential cosmological solutions with two factor spaces in EGB model with $$\Lambda = 0$$ Λ=0 revisited

Abstract

Abstract We study exact cosmological solutions in D-dimensional Einstein–Gauss–Bonnet model (with zero cosmological term) governed by two non-zero constants: $$\alpha _1$$ α1 and $$\alpha _2$$ α2 . We deal with exponential dependence (in time) of two scale factors governed by Hubble-like parameters $$H >0$$ H>0 and h, which correspond to factor spaces of dimensions $$m >2$$ m>2 and $$l > 2$$ l>2 , respectively, and $$D = 1 + m + l$$ D=1+m+l . We put $$h \ne H$$ h≠H and $$mH + l h \ne 0$$ mH+lh≠0 . We show that for $$\alpha = \alpha _2/\alpha _1 > 0$$ α=α2/α1>0 there are two (real) solutions with two sets of Hubble-like parameters: $$(H_1, h_1)$$ (H1,h1) and $$(H_2, h_2)$$ (H2,h2) , which obey: $$ h_1/ H_12), (12, 11), (11,16), (15, 6)$$ (m,l)=(9,l>2),(12,11),(11,16),(15,6) .