Particlization in hybrid models

TL;DR

This paper details the technical process of converting fluid descriptions to particles in hybrid heavy-ion collision models, focusing on hypersurface determination and sampling methods, including issues like negative contributions.

Contribution

It provides a detailed methodology for particlization in 3+1D hybrid models, addressing hypersurface finding and particle sampling techniques.

Findings

Effective hypersurface determination in 3+1D models

Sampling procedures for particle distributions

Analysis of negative contributions in Cooper-Frye

Abstract

In hybrid models, which combine hydrodynamical and transport approaches to describe different stages of heavy-ion collisions, conversion of fluid to individual particles, particlization, is a non-trivial technical problem. We describe in detail how to find the particlization hypersurface in a 3+1 dimensional model, and how to sample the particle distributions evaluated using the Cooper-Frye procedure to create an ensemble of particles as an initial state for the transport stage. We also discuss the role and magnitude of the negative contributions in the Cooper-Frye procedure.