The Matter Bounce Curvaton Scenario
  Massless scalar fields originating in a quantum vacuum state acquire a scale-invariant spectrum of fluctuations in a matter-dominated contracting universe. We show that these isocurvature fluctuations transfer to a scale-invariant spectrum of curvature fluctuations during a non-singular bounce phase. This provides a mechanism for enhancing the primordial adiabatic fluctuations and suppressing the ratio of tensor to scalar perturbations. Moreover, this mechanism leads to new sources of non-Gaussianity of curvature perturbations. 
Yi-Fu Cai, Robert Brandenberger and Xinmin Zhang (Arizona State,   McGill and IHEP Beijing)
hep-th astro-ph.CO gr-qc hep-ph