Note on the bispectrum and one-loop corrections in single-field inflation with primordial black hole formation

Understand

Primordial black holes can be formed from the collapse of large-amplitude perturbation on small scales in the early Universe.

• Such an enhanced spectrum can be realized by introducing a flat region in the potential of single-field inflation, which makes the inflaton go into a temporary ultraslow-roll period.
• In this paper, we calculate the bispectrum of curvature perturbation in such a scenario.
• We explicitly confirm that bispectrum satisfies Maldacena's theorem.