Simple, exact model of quasisingle field inflation

In this paper we present a simple but exact model of quasisingle field inflation [X. Chen and Y. Wang, Quasi-single field inflation and non-Gaussianities, J. Cosmol. Astropart. Phys. 04 (2010) 027, X. Chen and Y. Wang, Large non-Gaussianities with intermediate shapes from quasisingle field inflation, Phys. Rev. D 81, 063511 (2010)], in which the couplings between perturbations are completely controlled, and for instance can be made constant with any desired value. This provides a way to numerically implement quasisingle field inflation and to test its predictions in various regimes. We find that the numerics agree to high accuracy with the analytical predictions for the shape of the bispectrum, given a fixed overall scale. Also, we find reasonable agreement for the amplitude of the isosceles bispectrum, given a fixed base side.