Abstract:
In this talk, we present whether the new ekpyrotic scenario
can be embedded into ten-dimensional supergravity. We use that the
scalar potential obtained from flux compactifications of type II
supergravity with sources has a universal scaling with respect to the
dilaton and the volume mode. Similar to the investigation of
inflationary models, we find very strong constraints ruling out
ekpyrosis from analyzing the fast-roll conditions. We conclude that
flux compactifications tend to provide potentials that are neither too
flat and positive (inflation) nor too steep and negative (ekpyrosis).