One-loop corrections to the power spectrum in general single-field inflation

We perfom a thorough computation of the one-loop corrections from both scalar and tensor degrees of freedom to the power spectrum of curvature fluctuations for non-canonical Lagrangians in single-field inflation. We consider models characterized by a small sound speed cs, which produce large non-Gaussianities. As expected, the corrections turn out to be inversely proportional to powers of cs; evaluating their amplitudes it is then possible to derive some theoretical bounds on the sound speed by requesting the conditions necessary for perturbation theory to hold.