Warped Ricci-flat reductions
  We present a simple class of warped-product vacuum (Ricci-flat) solutions to ten and eleven-dimensional supergravity, where the internal space is flat and the warp factor supports de Sitter (dS) and anti-de Sitter (AdS) vacua in addition to trivial Minkowski vacua. We outline the construction of consistent Kaluza-Klein (KK) reductions and show that, although our vacuum solutions are non-supersymmetric, these are closely related to the bosonic part of well-known maximally supersymmetric reductions on spheres. We comment on the stability of our solutions, noting that (A)dS$_3$ vacua pass routine stability tests. 
Eoin \'O Colg\'ain, M.M. Sheikh-Jabbari, Justin F. V\'azquez-Poritz,   Hossein Yavartanoo, Zhibai Zhang
hep-th