Production of non-gaussianities in a bouncing phase
  We compute the level of non-gaussianities produced by a cosmological bouncing phase in the minimal non-singular setup that lies within the context of General Relativity when the matter content consists of a simple scalar field with a standard kinetic term. Such a bouncing phase is obtained by requiring that the spatial sections of the background spacetime be positively curved. We restrict attention to the close vicinity of the bounce by Taylor expanding the scale factor, the scalar field and its potential in powers of the conformal time around the bounce. We find that possibly large non-gaussianities are generically produced at the bounce itself and also discuss which shapes of non-gaussianities are mostly likely to be produced. 
Xian Gao (Tokyo Institute of Technology), Marc Lilley (Dept of   Mathematics & Applied Mathematics, University of Cape Town)...
gr-qc astro-ph.CO hep-th