Blue spectral inflation

TL;DR

This paper investigates the nonlinear second order Abel equation related to slow-roll inflation, discovering a new eigenvalue spectrum in the blue regime that aligns with observational data.

Contribution

It introduces a novel eigenvalue spectrum in the blue regime for the Abel equation, providing better fits to COBE and ground-based CMB data.

Findings

New eigenvalue spectrum in the blue regime

Consistent fits to COBE data

Alignment with recent CMB experiments

Abstract

We reconsider the nonlinear second order Abel equation of Stewart and Lyth, which follows from a nonlinear second order slow-roll approximation. We find a new eigenvalue spectrum in the blue regime. Some of the discrete values of the spectral index n_s have consistent fits to the cumulative COBE data as well as to recent ground-base CMB experiments.