Axion monodromy inflation with multi-natural modulations

TL;DR

This paper explores axion monodromy inflation models with sinusoidal modulations, demonstrating they can produce large tensor-to-scalar ratios and significant spectral index running while maintaining sub-Planckian decay constants.

Contribution

It introduces a potential with multiple sinusoidal modulations in axion monodromy inflation, achieving observable predictions with sub-Planckian decay constants and analyzing reheating processes.

Findings

Tensor-to-scalar ratio r_T ~ 0.16

Large negative spectral index running α_s ~ -0.02 to -0.03

Sub-Planckian decay constants in the model

Abstract

We study parameter space in the axion monodromy inflation corrected by dynamically generated terms involving with the axion. The potential has the linear potential with multiple sinusoidal functions, which play a role in generating modulations. We show that this potential leads both to a large tensor-to-scalar ratio $r_T \sim 0.16$ and to a large negative running of spectral index $\alpha_s \sim - (0.02 -0.03)$. To realize these results, a small hierarchy among dynamical scales is required whereas the decay constants in sinusoidal functions remain sub-Planckian in this model. We discuss also reheating process after the inflation in a bottom-up approach.