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

TL;DR

This study uses lattice simulations to analyze how multi-field inflation models affect parametric resonance and tachyonic preheating, revealing suppression effects and conditions for efficient preheating.

Contribution

It demonstrates the suppression of parametric resonance due to four-leg interactions and highlights the importance of three-leg interactions for effective tachyonic preheating in multi-field inflation.

Findings

Resonance suppression occurs with four-leg interactions in multi-field models.

Tachyonic preheating remains effective with three-leg interactions regardless of the number of fields.

Without tachyonic contributions, traditional reheating theory applies.

Abstract

We investigate the feasibility of explosive particle production via parametric resonance or tachyonic preheating in multi-field 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 sub-dominant, we observe a slight enhancement of tachyonic preheating. Thus, in order for preheating after multi-field 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.