Numerical tiling-based simulations of decoherence in multifield models of inflation

TL;DR

This paper introduces a flexible, numerically stable framework for simulating decoherence effects in multifield inflation models, enabling detailed studies of open-system dynamics without relying on slow-roll assumptions.

Contribution

It develops a general, efficient numerical method for modeling open-system effects on inflationary perturbations, extending previous approaches to multiple fields and arbitrary decoherence sequences.

Findings

Framework is numerically stable and flexible

Compatible with nonlinear numerical codes

Allows detailed control over decoherence parameters

Abstract

In previous work, we developed a method for computing two-point correlators by decomposing the mode degrees of freedom into fast and slow components. Building on this framework, we present a numerical implementation to study the evolution of primordial scalar perturbations under controlled state deformations induced by the simplest environment corrections from the Lindblad equation. The primary contribution of this work is the development of a numerically stable and flexible framework for implementing open-system effects in inflationary perturbations, rather than the extraction of concrete predictions for the primordial spectrum. Our approach generalizes to an arbitrary number of degrees of freedom and does not rely on the slow-roll approximation. The computational routine is numerically efficient and allows users to configure arbitrary sequences of decoherence events, with full control over their duration, shape, amplitude and effective wavelength range. The resulting outputs are compatible with nonlinear numerical codes, enabling studies of how decoherence effects propagate during reheating.