Gravitational dark matter production in Palatini preheating

Understand

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.