Power Spectrum and Signatures for Cascade Inflation

TL;DR

This paper derives the power spectrum for cascade inflation in M-theory, revealing distinctive signatures like power suppression, oscillations, and spectral index steps, which can be used to test the theory observationally.

Contribution

It provides the first detailed derivation of the power spectrum for cascade inflation, linking features in the inflaton potential to observable signatures and M-theory physics.

Findings

Power suppression at small scales in the spectrum.

Oscillations around horizon crossing scales.

Stepwise decrease in the scalar spectral index.

Abstract

The power spectrum of M-theory cascade inflation is derived. It possesses three distinctive signatures: a decisive power suppression at small scales, oscillations around the scales that cross the horizon when the inflaton potential jumps and stepwise decrease in the scalar spectral index. All three properties result from features in the inflaton potential. Cascade inflation realizes assisted inflation in heterotic M-theory and is driven by non-perturbative interactions of N M5-branes. The features in the inflaton potential are generated whenever two M5-branes collide with the boundaries. The derived small-scale power suppression serves as a possible explanation for the dearth of observed dwarf galaxies in the Milky Way halo. The oscillations, furthermore, allow to directly probe M-theory by measurements of the spectral index and to distinguish cascade inflation observationally from other string inflation models.