Hybrid inflation and waterfall field in string theory from D7-branes
  We present an explicit string realisation of a cosmological inflationary
scenario we proposed recently within the framework of type IIB flux
compactifications in the presence of three magnetised D7-brane stacks.
Inflation takes place around a metastable de Sitter vacuum. The inflaton is
identified with the volume modulus and has a potential with a very shallow
minimum near the maximum. Inflation ends due to the presence of "waterfall"
fields that drive the evolution of the Universe from a nearby saddle point
towards a global minimum with tuneable vacuum energy describing the present
state of our Universe.
