A simple, exact, model of quasi-single field inflation

Understand

In this note we present a simple but exact model of quasi-single field inflation \cite{Chen:2009zp, Chen:2009we}, 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 quasi-single field inflation and to test its predictions in various regimes.
• We confirm that the numerics agree to good accuracy with the analytical predictions for the isosceles bispectrum and the full shape function.