$<m_T>$ excitation function: Freeze-out and equation of state dependence

dc.creatorPetersen, Hannah
dc.creatorSteinheimer, Jan
dc.creatorBleicher, Marcus
dc.creatorStoecker, Horst
dc.date2009-02-27
dc.date2009-04-14
dc.date.accessioned2026-07-07T13:09:48Z
dc.date.available2026-07-07T13:09:48Z
dc.descriptionAn integrated Boltzmann+hydrodynamics transport approach is applied to investigate the dependence of the mean transverse mass on the freeze-out and the equation of state over the energy range from $E_{\rm lab}=2-160A $GeV. This transport approach based on the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) with an intermediate hydrodynamic stage allows for a systematic comparison without adjusting parameters. We find that the multiplicities of pions and protons are rather insensitive to different freeze-out prescriptions and changes in the equation of state, but the yields are slightly reduced in the hybrid model calculation compared to a pure transport calculation while the (anti)kaon multiplicities are increased. The mean transverse mass excitation functions of all three particle species are found to be sensitive to the different freeze-out treatments as well as to the equation of state. We find that the bag model equation of state with a strong first order phase transition is in qualitative agreement with the experimentally observed step-like behaviour in the < m_T > excitation function. The hybrid model with a hadron gas equation of state leads to a overestimation of the < m_T >, especially at higher energies. However, non-equilibrium effects seem also to be substantial as is suggested by the comparison with standard UrQMD results.
dc.description12 pages, 8 figures, discussion extended, final version to appaer in J. Phys. G
dc.identifierhttps://arxiv.org/abs/0902.4866
dc.identifierhttp://arxiv.org/abs/0902.4866
dc.identifierJ.Phys.G36:055104,2009
dc.identifierdoi:10.1088/0954-3899/36/5/055104
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/228859
dc.subjectNuclear Theory
dc.subjectHigh Energy Physics - Phenomenology
dc.subjectNuclear Experiment
dc.title$<m_T>$ excitation function: Freeze-out and equation of state dependence
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