Numerical Study of Inflationary Preheating with Arbitrary Power-law Potential and a Realization of Curvaton Mechanism

During inflationary preheating, the energy stored in the inflaton field is rapidly converted into excitations of other entropy fields. This stage is characterized by exponential particle production due to parametric resonance and is notoriously difficult to analyze using analytic methods. We develop a detailed numerical simulation to investigate inflationary preheating when the potential of the inflaton is a power-law function with arbitrary power index. To achieve a successful graceful exit from a primordial inflationary phase to a smooth, oscillatory phase during preheating, we assume the inflaton potential reduces to a quadratic function in the infrared regime, which may be regarded as a mass term at low-energy scales. With this simplification, our numerical method may be applied to unconventional chaotic inflation models. To demonstrate its validity, we numerically analyze the preheating stage of axion-monodromy inflation, which is inspired by string theory. By performing perturbation analyses, our result shows that the power spectrum of primordial curvature perturbation can be dominated by fluctuations of entropy field rather than those of inflaton, which can be regarded as a particular realization of the curvaton mechanism through a preheating process.