The running curvaton

TL;DR

This paper introduces a curvaton mechanism active during preheating with a running mass, analyzing its production via resonance, and calculating key cosmological observables, independent of the inflaton potential.

Contribution

It proposes a novel curvaton model during preheating with a running mass, analyzing resonance production and deriving independent power spectrum and non-Gaussianity predictions.

Findings

Power spectrum $P_\zeta$ calculated analytically.

Non-Gaussian parameter $f_{NL}$ derived.

Results are independent of inflaton potential.

Abstract

Inspired by \cite{Jiang:2018uce}, we propose a similar curvaton mechanism whose realization occurs in preheating process, in which the effective mass is running (its potential consists of coupling part and exponential part whose contribution is subdominant comparing to the coupling part). The production of curvaton contains the cases of narrow resonance and broad resonances whose criteria comes via the spectral index of curvaton. Since the inflationary potential is chaotic inflation (quadratic potential), it could smoothly transit into the preheating process. Once the entropy perturbation transferred into curvature perturbation, we will use $\delta N$ formalism to investigate its validity. By neglecting the contribution of exponential potential of curvaton, we calculate power spectrum $P_\zeta$ and non linear Non-Gaussian parameter $f_{NL}$. Our calculation analytically shows that these two observables are independent of potential of inflaton. Finally, as the curvaton almost decay (inflaton field vanishes), the exponential potential will be approaching a constant of order of cosmological constant, which may play a role of dark energy.