The running curvaton
  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.
