Particlization in fluid dynamical simulations of heavy-ion collisions: The iS3D module

TL;DR

The iS3D module provides a versatile Monte-Carlo implementation for simulating hadron emission in heavy-ion collisions, allowing exploration of uncertainties in the particlization process and validation against theoretical expectations.

Contribution

It introduces a flexible, validated Monte-Carlo particlization module with multiple non-equilibrium correction options for heavy-ion collision simulations.

Findings

The module accurately reproduces theoretical distributions.

Different correction choices impact the particle spectra.

Validation confirms high precision of the sampling method.

Abstract

The iS3D particlization module simulates the emission of hadrons from heavy-ion collisions via Monte-Carlo sampling of the Cooper-Frye formula which converts fluid dynamical information into local phase-space distributions for hadrons. The code package includes multiple choices for the non-equilibrium correction to these distribution functions: the 14-moment approximation, first-order Chapman-Enskog expansion, and two types of modified equilibrium distributions. This makes it possible to explore to what extent heavy-ion experimental data are sensitive to different choices for $\delta f_n$, presently the main source of theoretical uncertainty in the particlization stage. We validate our particle sampler with a high degree of precision by generating several million hadron emission events from a longitudinally boost-invariant hypersurface and comparing the event-averaged particle spectra and space-time distributions to the Cooper-Frye formula.