Gravitational waves induced from string axion model of inflation

Abstract

We study the production of gravitational waves from primordial scalar perturbations in a string axion inflationary model with subleading nonperturbative corrections. In such a model, the subleading nonperturbative effects can superimpose steep cliffs and gentle plateaus onto the leading axion potential. Such an inflationary potential both matches the Planck observations at CMB scales and gives rise to an enhancement in the scalar power spectrum at small scales. We calculate the second-order gravitational wave signatures induced by the scalar density perturbations, and find that the signal can be detected by the space-based laser interferometers in the future.