Signature of short distance physics on inflation power spectrum and CMB anisotropy

TL;DR

This paper develops a new formalism to analyze how non-canonical inflaton properties, like compositeness or decay width, affect the inflation power spectrum and CMB anisotropy, with potential observational signatures.

Contribution

It introduces a general method using the Källén-Lehmann spectral function to compute the power spectrum for non-canonical inflaton models in quasi-de Sitter space.

Findings

Decay width suppresses large-scale power.

Composite inflaton causes oscillations in the power spectrum.

Potential observational signatures in WMAP and PLANCK data.

Abstract

The inflaton field responsible for inflation may not be a canonical fundamental scalar. It is possible that the inflaton is a composite of fermions or it may have a decay width. In these cases the standard procedure for calculating the power spectrum is not applicable and a new formalism needs to be developed to determine the effect of short range interactions of the inflaton on the power spectrum and the CMB anisotropy. We develop a general formalism for computing the power spectrum of curvature perturbations for such non-canonical cases by using the flat space K\"all\'en-Lehmann spectral function in curved quasi-de Sitter space assuming implicitly that the Bunch-Davis boundary conditions enforces the inflaton mode functions to be plane wave in the short wavelength limit and a complete set of mode functions exists in quasi-de Sitter space. It is observed that the inflaton with a decay width suppresses the power at large scale while a composite inflaton's power spectrum oscillates at large scales. These observations may be vindicated in the WMAP data and confirmed by future observations with PLANCK.