On the Suppression of Parametric Resonance and the Viability of Tachyonic Preheating after Multi-Field Inflation

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We investigate the feasibility of explosive particle production via parametric resonance or tachyonic preheating in multifield inflationary models by means of lattice simulations. We observe a strong suppression of resonances in the presence of four-leg interactions between the inflaton fields and a scalar matter field, leading to insufficient preheating when more than two inflatons couple to the same matter field. This suppression is caused by a dephasing of the inflatons that increases the effective mass of the matter field. Including three-leg interactions leads to tachyonic preheating, which is not suppressed by an increase in the number of fields. If four-leg interactions are subdominant, we observe a slight enhancement of tachyonic preheating. Thus, in order for preheating after multifield inflation to be efficient, one needs to ensure that three-leg interactions are present. If no tachyonic contributions exist, we expect the old theory of reheating to be applicable.


Physical Review D