  The low energy effective action of quantum gravity may include the higher
curvature terms such as the Gauss-Bonnet term. The inflaton dynamics may be
affected by the Gauss-Bonnet term if there is an inflaton-Gauss-Bonnet
coupling. We show that an inflation model with a simple power law potential is
made viable if it is coupled to the Gauss-Bonnet term since the prediction on
the scalar spectral index and the tensor-to-scalar ratio are modified. We
further point out that such a model predicts huge amount of gravitational waves
at the high frequency range around 100GHz--100THz through the perturbative
inflaton decay into gravitons induced by the Gauss-Bonnet term. Thus the
spectrum of high frequency gravitational background is a unique feature of the
inflation models with a Gauss-Bonnet correction.
