Natural inflation at the GUT scale

TL;DR

This paper proposes a warm inflation model with a Pseudo-Nambu-Goldstone boson at the GUT scale, addressing spectral index issues and linking to neutrino mass generation and leptogenesis, with testable non-Gaussianity predictions.

Contribution

It introduces a GUT-scale PNGB warm inflation model that aligns with observational data and connects to neutrino physics and leptogenesis.

Findings

Achieves spectral index consistent with WMAP data

Predicts large non-Gaussianity detectable by PLANCK

Links inflation to neutrino mass generation and lepton asymmetry

Abstract

Natural inflation driven by Pseudo-Nambu-Goldstone bosons have a problem that the nearly scale invariant spectrum of density perturbations is attained only when the symmetry breaking scale is of the order of Planck scale. We show here that if one couples the PNGB to a thermal bath as in warm inflation models, the amplitude and spectral index which agrees with the WMAP data is obtained with the symmetry breaking in the GUT scale. We give a GUT model of PNGB arising out of spontaneously broken lepton number at the GUT scale which gives rise to heavy Majorana masses for the right handed neutrinos which is needed in see-saw models. This model also generates a lepton asymmetry because of the derivative coupling of the PNGB to the lepton current. A characteristic feature of this model is the prediction of large non-gaussianity which may be observed in the forthcoming PLANCK experiment.