Direct photon emission in Heavy Ion Collisions from Microscopic Transport Theory and Fluid Dynamics

TL;DR

This paper investigates direct photon emission in heavy-ion collisions using a hybrid model combining hydrodynamics and microscopic transport, comparing results with experimental data and making predictions for future experiments.

Contribution

It introduces a relativistic hybrid model integrating hydrodynamics with transport theory to study photon emission in heavy-ion collisions.

Findings

Hybrid model successfully reproduces experimental photon spectra.

Transition scenarios significantly affect photon emission predictions.

Predictions for CBM-experiment provide guidance for future measurements.

Abstract

Direct photon emission in heavy-ion collisions is calculated within a relativistic micro+macro hybrid model and compared to the microscopic transport model UrQMD. In the hybrid approach, the high-density part of the collision is calculated by an ideal 3+1-dimensional hydrodynamic calculation, while the early (pre-equilibrium-) and late (rescattering-) phase are calculated with the transport model. Different scenarios of the transition from the macroscopic description to the transport model description and their effects are studied. The calculations are compared to measurements by the WA98-collaboration and predictions for the future CBM-experiment are made.