# Nonlinear Dynamics of Preheating after Multifield Inflation with Nonminimal Couplings

## TL;DR

This paper investigates the nonlinear dynamics of preheating in multifield inflation models with nonminimal couplings, revealing efficient particle production and strong attractor behavior that preserve predictions consistent with observations.

## Contribution

It provides the first lattice simulation analysis of nonlinear effects in multifield inflation with nonminimal couplings, highlighting the persistence of single-field attractor behavior.

## Key findings

- Efficient particle production leads to nearly instantaneous preheating.
- Strong single-field attractor behavior persists, suppressing multifield signatures.
- Predictions for primordial observables remain consistent with current measurements.

## Abstract

We study the post-inflation dynamics of multifield models involving nonminimal couplings using lattice simulations to capture significant nonlinear effects like backreaction and rescattering. We measure the effective equation of state and typical time-scales for the onset of thermalization, which could affect the usual mapping between predictions for primordial perturbation spectra and measurements of anisotropies in the cosmic microwave background radiation. For large values of the nonminimal coupling constants, we find efficient particle production that gives rise to nearly instantaneous preheating. Moreover, the strong single-field attractor behavior that was previously identified persists until the end of preheating, thereby suppressing typical signatures of multifield models. We therefore find that predictions for primordial observables in this class of models retain a close match to the latest observations.