- Multi-particle interactions within the UrQMD approach (2011)
- A mechanism for locally density-dependent dynamic parton rearrangement and fusion has been implemented into the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) approach. The same mechanism has been previously built in the Quark Gluon String Model (QGSM). This rearrangement and fusion approach based on parton coalescence ideas enables the description of multi-particle interactions, namely 3 -> 3 and 3 -> 2, between (pre)hadronic states in addition to standard binary interactions. The UrQMD model (v2.3) extended by these additional processes allows to investigate implications of multi-particle interactions on the reaction dynamics of ultrarelativistic heavy ion collisions. The mechanism, its implementation and first results of this investigation are presented and discussed.
- Implications on the collision dynamics via azimuthal sensitive HBT from UrQMD : the Seventh Workshop on Particle Correlations and Femtoscopy, September 20 - 24 2011, University of Tokyo, Japan (2011)
- We explore the shape and orientation of the freezeout region of non-central heavy ion collisions. For this we fit the freezeout distribution with a tilted ellipsoid. The resulting tilt angle is compared to the same tilt angle extracted via an azimuthally sensitive HBT analysis. This allows to access the tilt angle experimentally, which is not possible directly from the freezeout distribution. We also show a systematic study on the system decoupling time dependence on dNch/dh, using HBT results from the UrQMD transport model. In this study we found that the decoupling time scales with (dNch/dh)1/3 within each energy, but the scaling is broken across energies.
- HBT radii from the UrQMD transport approach at different energies (2011)
- We present results on Hanbury Brown-Twiss (HBT) radii extracted from the Ultra-relativistic Molecular Dynamics (UrQMD) approach to relativistic heavy ion collisions. The present investigation provides a comparison of results from pure hadronic transport calculations to a Boltzmann + Hydrodynamic hybrid approach with an intermediate hydrodynamic phase. For the hydrodynamic phase different Equations of State (EoS) have been employed, i.e. bag model, hadron resonance gas and a chiral EoS. The influence of various freeze-out scenarios has been investigated and shown to be negligible if hadronic rescatterings after the hydrodynamic evolution are included. Furthermore, first results of the source tilt from azimuthal sensitive HBT and the direct extraction from the transport model are presented and exhibit a very good agreement with E895 data at AGS.