Relativistic Heavy-Ion Collisions

PHSD-PHQMD

A unified non-equilibrium microscopic transport approach for the description of the dynamics of strongly-interacting hadronic and partonic matter.

Au+Au simulation movie

PHSD-PHQMD is a Fortran-based unified transport simulation framework for relativistic nucleus-nucleus collisions. It combines two complementary descriptions of baryon dynamics: PHSD, which uses mean-field BUU transport, and PHQMD, which uses a Quantum Molecular Dynamics (QMD) n-body approach. The overview image below summarizes this modeling scheme.

  • In both modes, the subsequent evolution includes quarks, gluons, mesons, and hadrons, propagated within non-equilibrium Kadanoff-Baym and BUU dynamics.
  • Interactions are handled through a collision integral for off-shell hadrons and QGP partons, with the Dynamical-QuasiParticle Model (DQPM) describing the partonic medium.
  • Final-state nuclear fragments can be reconstructed with MST (Minimum Spanning Tree), SACA (Simulated Annealing Cluster Algorithm), or coalescence-based algorithms.
  • The simulated events are exported in OSCAR, ROOT, and Rivet formats.
PHSD-PHQMD overview

New Features

Special Features of PHSD/PHQMD

  • Possibility to study mean-field versus QMD dynamics based on one framework
  • Kadanoff-Baym dynamics for off-shell hadrons and partons
  • Phase transition from hadronic to partonic matter
  • Description of QGP in terms of strongly interacting quasiparticles based on DQPM in-line with lQCD EoS
  • Chiral symmetry restoration via Schwinger mechanism for string breaking
  • In-medium effects within G(T)-matrix for strangeness
  • Realization of n↔m reactions for specific channels
  • Open/hidden charm/bottom dynamics
  • Dark matter: dark photons
  • Electromagnetic probes (dileptons, photons)
  • PHQMD mode:
  • - EoS with hard, soft and soft momentum dependent potential
  • - Mechanisms for cluster production in PHQMD: dynamical, kinetic and coalescence

PHSD/PHQMD Modeling Workflow

A unified non-equilibrium microscopic transport approach for heavy-ion and hadron-nucleus reactions from SIS to LHC energies.

1. Two Initialization Modes

PHSD mode: A+A initialization and baryon propagation with mean-field dynamics (BUU).

PHQMD mode: A+A initialization and baryon propagation with Quantum Molecular Dynamics (QMD).

2. Shared Transport Core

Common propagation of partons (quarks, gluons) and mesons with off-shell mean-field dynamics.

3. Collision Integral

Unified interaction treatment between hadrons and partons, including the QGP phase.

4. Cluster Recognition

MST, SACA, and coalescence mechanisms are available to reconstruct final-state clusters.

5. Final Outputs

Event-level outputs prepared for analysis workflows in OSCAR, ROOT, and Rivet-like formats.

6. Continuous Dynamics

No artificial micro-to-macro handover: a continuous dynamical description from initial state to final hadrons and leptons.

Navigate The Site

All content from the previous PHSD-PHQMD website is preserved and reorganized.

PHSD PHSD PHQMD PHQMD