Refine
Document Type
- Preprint (35) (remove)
Language
- English (35)
Has Fulltext
- yes (35)
Is part of the Bibliography
- no (35)
Keywords
- Kollisionen schwerer Ionen (6)
- heavy ion collisions (6)
- UrQMD (4)
- QGP (3)
- Ultrarelativistic Quantum Molecular Dynamics (3)
- Molekulare Dynamik (2)
- Quark Gluon Plasma (2)
- Quark-Gluon-Plasma (2)
- UrQMD Modell (2)
- ultrarelativistisch (2)
- Absorption (1)
- Bremsstrahlung (1)
- Charmonium Produktion (1)
- Charmonium production (1)
- Deuteron (1)
- Drell-Yan (1)
- Drell-Yan production (1)
- Drell-Yan-Prozess (1)
- Dynamik (1)
- Energie (1)
- Freiheitsgrad (1)
- Hadron (1)
- J/ϕ (1)
- Kollision (1)
- Korrelation (1)
- Meson (1)
- Monte-Carlo model for relativistic heavy ion collisions (1)
- QGP signals (1)
- Quanten-Molekular-Dynamic (1)
- Quanten-Molekular-Dynamik (1)
- SPS (1)
- Statistical model (1)
- URQMD (1)
- Ultra-relativistic Quantum Molecular Dynamics model (1)
- Ultrarelativisitic Quantum Molecular Dynamics model (1)
- Ultrarelativisitisches (1)
- Ultrarelativistic Quantum Molecular Model (1)
- Ultrarelativistisches Quant Molekulares Modell (1)
- UrQMD model (1)
- absorption (1)
- bremsstrahlung (1)
- collision (1)
- degrees of freedom (1)
- deuteron (1)
- dileptons (1)
- energy (1)
- equation of state (1)
- flow (1)
- hadron hadron Kollision (1)
- hadron hadron collision (1)
- hadronic (1)
- hadronic freeze-out (1)
- heavy-ion collisions (1)
- high energie (1)
- hohe Energie (1)
- microscopic transport theory (1)
- mikroskopische Transporttheorie (1)
- particle ratios (1)
- quark-gluon plasma (1)
- quark-gluon-plasma (1)
- relativistic heavy ion collision (1)
- relativistische schwere Ion Kollision (1)
- schwere Ion Kollision (1)
- schwere Ionen Kollision (1)
- space-momentum correlation (1)
- strangeness (1)
- thermalization (1)
- ultra-relativistic heavy ion collision (1)
- ultrarelativistic heavy-ion collision (1)
- ultrarelativistische (1)
- ultrarelativistische Kollision des schweren Ionen (1)
Institute
A study of secondary Drell-Yan production in nuclear collisions is presented for SPS energies. In addition to the lepton pairs produced in the initial collisions of the projectile and target nucleons, we consider the potentially high dilepton yield from hard valence antiquarks in produced mesons and antibaryons. We calculate the secondary Drell-Yan contributions taking the collision spectrum of hadrons from the microscopic model URQMD. The con- tributions from meson-baryon interactions, small in hadron-nucleus interac- tions, are found to be substantial in nucleus-nucleus collisions at low dilepton masses. Preresonance collisions of partons may further increase the yields.
Quantum Molecular Dynamics (QMD) calculations of central collisions between heavy nuclei are used to study fragment production and the creation of collective flow. It is shown that the final phase space distributions are compatible with the expectations from a thermally equilibrated source, which in addition exhibits a collective transverse expansion. However, the microscopic analyses of the transient states in the intermediate reaction stages show that the event shapes are more complex and that equilibrium is reached only in very special cases but not in event samples which cover a wide range of impact parameters as it is the case in experiments. The basic features of a new molecular dynamics model (UQMD) for heavy ion collisions from the Fermi energy regime up to the highest presently available energies are outlined.
The behavior of hadronic matter at high baryon densities is studied within Ultrarelativistic Quantum Molecular Dynamics (URQMD). Baryonic stopping is observed for Au+Au collisions from SIS up to SPS energies. The excitation function of flow shows strong sensitivities to the underlying equation of state (EOS), allowing for systematic studies of the EOS. Effects of a density dependent pole of the rho-meson propagator on dilepton spectra are studied for different systems and centralities at CERN energies.
We study the thermodynamic properties of infinite nuclear matter with the Ultrarelativistic Quantum Molecular Dynamics (URQMD), a semiclassical transport model, running in a box with periodic boundary conditions. It appears that the energy density rises faster than T4 at high temperatures of T approx. 200 - 300 MeV. This indicates an increase in the number of degrees of freedom. Moreover, We have calculated direct photon production in Pb+Pb collisions at 160 GeV/u within this model. The direct photon slope from the microscopic calculation equals that from a hydrodynamical calculation without a phase transition in the equation of state of the photon source.
The microscopic phasespace approach URQMD is used to investigate the stopping power and particle production in heavy systems at SPS and RHIC energies. We find no gap in the baryon rapidity distribution even at RHIC. For CERN energies URQMD shows a pile up of baryons and a supression of multi-nucleon clusters at midrapidity.