A note on low energy effective theory of chromo-natural inflation in the light of BICEP2 results

Abstract

Recent result of BICEP2, revealing a larger value of tensor to scalar ratio (r), has opened up new investigations of the inflationary models to fit the experimental data. The experiment needs to reconfirm the results, specifically the consistency between Planck and BICEP2. On the other hand, the combined analysis of Planck and BICEP2, including the dust polarization uncertainty, brings down the upper limit on r. In this paper, we re-examine the low energy effective theory of chromo-natural inflation model and its generalization in view of such observational data. We find that the parameter space of the model admits a large value of r as well as other cosmological observables consistent with data.