Adiabatic Spectra During Slowly Evolving

Understand

In general, for single field, the scale invariant spectrum of curvature perturbation can be given by either its constant mode or its increasing mode.

• We show that during slowly expanding or contracting, the spectrum of curvature perturbation given by its increasing mode can be scale invariance.
• The perturbation mode can be naturally extended out of horizon, and the amplitude of perturbation is consistent with the observations.
• We briefly discuss the implement of this scenario.