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

## TL;DR

This paper introduces a simple, exact model of quasi-single field inflation with controllable couplings, enabling precise numerical testing of inflationary predictions and confirming analytical results.

## Contribution

The paper presents a novel, exact inflation model allowing for precise numerical analysis and validation of theoretical predictions in quasi-single field inflation.

## Key findings

- Numerical results agree with analytical predictions for bispectrum shapes.
- Couplings in the model can be set to constant values for testing.
- The model facilitates testing of inflationary scenarios across regimes.

## Abstract

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.