A smooth bouncing cosmology with scale invariant spectrum
Paolo Creminelli
ICTP
Wed, Apr. 25th 2007, 14:15
Salle Claude Itzykson, Bât. 774, Orme des Merisiers
We present a bouncing cosmology which evolves from the contracting to the expanding phase in a smooth way, without developing instabilities or pathologies and remaining in the regime of validity of 4d effective field theory. A nearly scale invariant spectrum of perturbations is generated during the contracting phase by an isocurvature scalar with a negative exponential potential and then converted to adiabatic. The model predicts a slightly blue spectrum, \$n_S >\sim 1\$, no observable gravitational waves and a high (but model dependent) level of non-Gaussianities with local shape. The model represents an explicit and predictive alternative to inflation, although, at present, it is clearly less compelling.