Kavli Affiliate: Misao Sasaki

| First 5 Authors: Shi Pi, Misao Sasaki, , ,

| Summary:

In the curvaton scenario, the curvature perturbation is generated after

inflation at the curvaton decay, which may have a prominent non-Gaussian

effect. For a model with a non-trivial kinetic term, an enhanced curvature

perturbation on a small scale can be realized, which can lead to copious

production of primordial black holes (PBHs) and induce secondary gravitational

waves (GWs). Using the probability distribution function (PDF) which takes full

nonlinear effects into account, we calculate the PBH formation. We find that

under the assumption that thus formed PBHs would not overclose the universe,

the non-Gaussianity of the curvature perturbation can be well approximated by

the local quadratic form, which can be used to calculate the induced GWs. In

this model the limit of large non-Gaussianity can be reached when the curvaton

energy fraction $r$ is small at the moment of curvaton decay. We also show that

in the $rto1$ limit the PDF is similar to that of ultraslow-roll inflation.

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