Higher curvature corrections to primordial fluctuations in slow-roll inflation

Abstract

We study higher curvature corrections to the scalar spectral index, the\ntensor spectral index, the tensor-to-scalar ratio, and the polarization of\ngravitational waves. We find that the higher curvature corrections can not be\nnegligible in the dynamics of the scalar field, although they are energetically\nnegligible. Indeed, it turns out that the tensor-to-scalar ratio could be\nenhanced and the tensor spectral index could be blue due to the Gauss-Bonnet\nterm. We estimate the degree of circular polarization of gravitational waves\ngenerated during the slow-roll inflation. We argue that the circular\npolarization can be observable with the help both of the Gauss-Bonnet and\nparity violating terms. We also present several examples to reveal\nobservational implications of higher curvature corrections for chaotic\ninflationary models.\n