Axion monodromy inflation with sinusoidal corrections

T Kobayashi,O Seto,Y Yamaguchi

doi:10.1093/ptep/ptu145

Abstract

We study the axion monodromy inflation with a non-perturbatively generated sinusoidal term. The potential form is a mixture between the natural inflation and the axion monodromy inflation potentials. The sinusoidal term is subdominant in the potential, but leaves significant effects on the resultant fluctuation generated during inflation. A larger tensor-to-scalar ratio can be obtained in our model. We study two scenarios, single inflation scenario and the double inflation scenario. In the first scenario, the axion monodromy inflation with a sufficient number of e-fold generates a larger tensor-to-scalar ratio about $0.1 - 0.15$ but also a tiny running of spectral index. In the second scenario of double inflation, axion monodromy inflation is its first stage and, we assume another inflation follows. In this case, our model can realize a larger tensor-to-scalar ratio and a large negative running of spectral index simultaneously.

Highlights

We study the axion monodromy inflation with a non-perturbatively generated sinusoidal term
Recent detection of the gravitational wave perturbation by BICEP2 [1] indicates its large amplitude and its tensor-to-scalar ratio of r T = 0.20+0.07 −0.05 (1)for a lensed-CDM plus tensor mode cosmological model, and r T = 0.16+0.06 (2)after foreground subtraction based on dust models
We consider the case that the axion monodromy inflation expands enough to solve the horizon and flatness problem and study other observables

Summary

Introduction

We study the axion monodromy inflation with a non-perturbatively generated sinusoidal term. The axion monodromy inflation with a sufficient number of e-folds generates a larger tensor-to-scalar ratio of about 0.1–0.15 and a tiny running of the spectral index. Our model can realize a larger tensor-to-scalar ratio and a large negative running of the spectral index simultaneously.

Results

Conclusion