On classical de Sitter and Minkowski solutions with intersecting branes
  Motivated by the connection of string theory to cosmology or particle
physics, we study solutions of type II supergravities having a four-dimensional
de Sitter or Minkowski space-time, with intersecting Dp-branes and orientifold
Op-planes. Only few such solutions are known, and we aim at a better
characterisation. Modulo a few restrictions, we prove that there exists no
classical de Sitter solution for any combination of D3/O3 and D7/O7, while we
derive interesting constraints for intersecting D5/O5 or D6/O6, or combinations
of D4/O4 and D8/O8. Concerning classical Minkowski solutions, we understand
some typical features, and propose a solution ansatz. Overall, a central
information appears to be the way intersecting Dp/Op overlap each other, a
point we focus on.
