Filtern
Erscheinungsjahr
- 1998 (7) (entfernen)
Dokumenttyp
- Preprint (5)
- Wissenschaftlicher Artikel (2)
Sprache
- Englisch (7)
Volltext vorhanden
- ja (7)
Gehört zur Bibliographie
- nein (7)
Schlagworte
- Kollisionen schwerer Ionen (3)
- heavy ion collisions (3)
- Drell-Yan (2)
- Molekulare Dynamik (2)
- Quark-Gluon-Plasma (2)
- Ultrarelativistic Quantum Molecular Dynamics (2)
- UrQMD (2)
- ultrarelativistisch (2)
- Dilepton (1)
- LHC (1)
- Meson (1)
- SPS (1)
- Ultra-relativistic Quantum Molecular Dynamics model (1)
- UrQMD Modell (1)
- dilepton (1)
- heavy ions (1)
- quark-gluon plasma (1)
- quark-gluon-plasma (1)
- schwere Ione (1)
Institut
- Physik (7)
In this paper, the concepts of microscopic transport theory are introduced and the features and shortcomings of the most commonly used ansatzes are discussed. In particular, the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) transport model is described in great detail. Based on the same principles as QMD and RQMD, it incorporates a vastly extended collision term with full baryon-antibaryon symmetry, 55 baryon and 32 meson species. Isospin is explicitly treated for all hadrons. The range of applicability stretches from E lab < 100$ MeV/nucleon up to E lab> 200$ GeV/nucleon, allowing for a consistent calculation of excitation functions from the intermediate energy domain up to ultrarelativistic energies. The main physics topics under discussion are stopping, particle production and collective flow.
We perform an event-by-event analysis of the transverse momentum distribution of final state particles in central Pb(160AGeV)+Pb collisions within a microscopic non-equilibrium transport model (UrQMD). Strong influence of rescattering is found. The extracted momentum distributions show less fluctuations in A+A collisions than in p+p reactions. This is in contrast to simplified p+p extrapolations and random walk models.
We study J/psi suppression in AB collisions assuming that the charmonium states evolve from small, color transparent configurations. Their interaction with nucleons and nonequilibrated, secondary hadrons is simulated us- ing the microscopic model UrQMD. The Drell-Yan lepton pair yield and the J/psi /Drell-Yan ratio are calculated as a function of the neutral transverse en- ergy in Pb+Pb collisions at 160 GeV and found to be in reasonable agreement with existing data.
Dissociation rates of J / psi's with comoving mesons : thermal versus nonequilibrium scenario.
(1998)
We study J/psi dissociation processes in hadronic environments. The validity of a thermal meson gas ansatz is tested by confronting it with an alternative, nonequilibrium scenario. Heavy ion collisions are simulated in the frame- work of the microscopic transport model UrQMD, taking into account the production of charmonium states through hard parton-parton interactions and subsequent rescattering with hadrons. The thermal gas and microscopic transport scenarios are shown to be very dissimilar. Estimates of J/psi survival probabilities based on thermal models of comover interactions in heavy ion collisions are therefore not reliable.