Gravitational dark matter production in Palatini preheating

TL;DR

This paper explores gravitational production of superheavy dark matter during preheating in a Palatini inflation model, demonstrating a mechanism for creating very massive scalar particles through purely gravitational effects.

Contribution

It introduces a new gravitational particle production mechanism for superheavy dark matter in Palatini inflation, extending previous work on inflaton particle production.

Findings

Efficient production of superheavy scalar particles via gravitational effects.

Scalar mass can reach around 10^{13} GeV, exceeding the Hubble scale.

Potential candidate for superheavy dark matter.

Abstract

We study preheating in plateau inflation in the Palatini formulation of general relativity, in a special case that resembles Higgs inflation. It was previously shown that the oscillating inflaton field returns to the plateau repeatedly in this model, and this leads to tachyonic production of inflaton particles. We show that a minimally coupled spectator scalar field can be produced even more efficiently by a similar mechanism. The mechanism is purely gravitational, and the scalar field mass can be of order $10^{13}$ GeV, larger than the Hubble scale by many orders of magnitude, making this a candidate for superheavy dark matter.