An exact model for enhancing/suppressing primordial fluctuations

Understand

Enhancements of primordial curvature fluctuations in single field inflation often involve departures from attractor trajectories in the phase space.

• We study enhancement/suppression of primordial fluctuations in one of the simplest models with exact background solutions for arbitrary initial conditions: a single field inflationary model with a piecewise exponential potential.
• We then present close to exact analytical solutions for primordial fluctuations in a general transition between two slow-roll attractors, valid whether the first slow parameter increases or decreases.
• The main features in the primordial spectrum are determined by the ratio of exponents of the potential.