Signatures of Planck corrections in a spiralling axion inflation model

McDonald, John (2015) Signatures of Planck corrections in a spiralling axion inflation model. Journal of Cosmology and Astroparticle Physics (5): 014. ISSN 1475-7516

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Abstract

The minimal sub-Planckian axion inflation model accounts for a large scalar-to-tensor ratio via a spiralling trajectory in the field space of a complex field Phi. Here we consider how the predictions of the model are modified by Planck scale-suppressed corrections. In the absence of Planck corrections the model is equivalent to a phi(4/3) chaotic inflation model. Planck corrections become important when the dimensionless coupling xi of |Phi|(2) to the topological charge density of the strongly-coupled gauge sector F (F) over tilde satisfies xi similar to 1. For values of |Phi| which allow the Planck corrections to be understood via an expansion in powers of |Phi|(2)/M-P1(2), we show that their effect is to produce a significant modification of the tensor-to-scalar ratio from its phi(4/3) chaotic inflation value without strongly modifying the spectral index. In addition, to leading order in |Phi|(2)/M-P1(2), the Planck modifications of n(s) and r satisfy a consistency relation, Delta n(s) = -Delta r/16. Observation of these modifications and their correlation would allow the model to be distinguished from a simple phi(4/3) chaotic inflation model and would also provide a signature for the influence of leading-order Planck corrections.