Primordial Fluctuations from Inflation with a Triad of Background Gauge Fields

TL;DR

This paper analyzes a novel inflation model with multiple gauge fields that maintains isotropy and predicts specific features in the primordial fluctuation spectra, consistent with current observational data.

Contribution

It derives the quadratic action for perturbations in a gauge-kinetic coupled multi-vector field inflation model and evaluates its observational predictions.

Findings

Predicted slightly red scalar spectra

Tensor-to-scalar ratio is suppressed

Model consistent with WMAP 7-year data

Abstract

We study the linear perturbation of the recently proposed model of inflation where a uniform gauge-kinetic coupling of the inflaton to multiple vector fields breaks the cosmic no-hair conjecture while maintaining the isotropy. We derive the general quadratic action for the perturbation and calculate the power spectra of scalar and tensor modes at the end of inflation by in-in formalism. It is shown that the model predicts slightly red spectra and the tensor-to-scalar ratio tends to be suppressed. The comparison with the data from WMAP 7-year does not impose strong constraints on the parameters and both weak- and strong- gauge-field regimes are consistent with the current observations.