Scale invariance via a phase of slow expansion
Scale invariance via a phase of slow expansion
We consider a cosmological scenario in which a scale-invariant spectrum of curvature perturbations is generated by a rapidly evolving equation of state on a slowly expanding background. This scenario generalizes the ``adiabatic ekpyrotic'' mechanism proposed recently by Khoury and Steinhardt [Phys. Rev. Lett. 104, 091301 (2010)]. Whereas the original proposal …