Non-Gaussianity from violation of slow-roll in multiple inflation
  Multiple inflation is a model based on N=1 supergravity wherein there are
sudden changes in the mass of the inflaton because it couples to 'flat
direction' scalar fields which undergo symmetry breaking phase transitions as
the universe cools. The resulting brief violations of slow-roll evolution
generate a non-gaussian signal which we find to be oscillatory and yielding
f_NL ~ 5-20. This is potentially detectable by e.g. Planck but would require
new bispectrum estimators to do so. We also derive a model-independent result
relating the period of oscillations of a phase transition during inflation to
the period of oscillations in the primordial curvature perturbation generated
by the inflaton.
