Bumpy inflation from explosive particle production

Abstract

We present a first-principles derivation of an effective inflaton potential with a bumpy feature. We consider the coupling of a spectator field χto the inflaton ϕsuch that χis massive enough for almost all values of ϕ, but becomes massless when the inflaton crossed the value ϕ_\star. This gives rise to a burst of χ-particle production at ϕ=ϕ_\star. By taking the backreaction of the particle production, we obtain a bumpy feature in the effective potential. We discover that for certain choices of the interaction constants and field scale relevant for particle production, the backreaction-induced bumpy effective potential can lead to a sizable enhancement in the curvature perturbation. In particular, the enhancement can be large enough to generate observationally relevant amounts of primordial black holes and stochastic gravitational wave backgrounds.

arXiv comment6 pages plus supplemental material. 3 figures