A fully integrated Boltzmann+hydrodynamics approach: Multiplicities, transverse dynamics and HBT

TL;DR

This paper introduces a hybrid model combining Boltzmann transport and hydrodynamics to simulate relativistic heavy ion collisions, enabling direct comparison of microscopic and macroscopic approaches with consistent initial conditions.

Contribution

It presents a novel integrated approach that couples Boltzmann transport with hydrodynamics for more accurate modeling of heavy ion reactions.

Findings

Consistent particle multiplicities across models

Reproduction of transverse mass excitation functions

Agreement with HBT radii data at SPS energies

Abstract

We present a coupled Boltzmann and hydrodynamics approach to relativistic heavy ion reactions. This hybrid approach is based on the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) transport approach with an intermediate hydrodynamical evolution for the hot and dense stage of the collision. This implementation allows to compare microscopic transport calculations with hydrodynamic calculations using exactly the same initial conditions and freeze-out procedure. Here, the results of the different calculations for particle multiplicities, the mean transverse mass excitation function and the HBT radii at all SPS energies are discussed in the context of the available data.