1,413 research outputs found
Event-by-event fluctuations of the charged particle ratio from non-equilibrium transport theory
The event by event fluctuations of the ratio of positively to negatively
charged hadrons are predicted within the UrQMD model. Corrections for finite
acceptance and finite net charge are derived. These corrections are relevant to
compare experimental data and transport model results to previous predictions.
The calculated fluctuations at RHIC and SPS energies are shown to be compatible
with a hadron gas. Thus, deviating by a factor of 3 from the predictions for a
thermalized quark-gluon plasma.Comment: This paper clarifies the previous predictions of Jeon and Koch
(hep-ph/0003168) and addresses issues raised in hep-ph/0006023. 2 Figures,
10pp, uses RevTe
Determination of the structure of the in collisions
Currently, the structure of the meson is unknown. Different
competing models of the exotic state exist, including the
possibilities that this state is either a mesonic molecule with dominating composition, a tetraquark, or a -gluon hybrid state. It is expected that the state is rather
strongly coupled to the channel and, therefore, can be produced in
and collisions at PANDA. We propose to test the
hypothetical molecular structure of by studying the or stripping reactions on a nuclear residue.Comment: 19 pages, 8 figures; version accepted in PL
Event-by-Event Analysis of Baryon-Strangeness Correlations: Pinning Down the Critical Temperature and Volume of QGP Formation
The recently proposed baryon-strangeness correlation (C_BS) is studied with a
string-hadronic transport model (UrQMD) for various energies from E_lab=4 AGeV
to \sqrt s=200 AGeV. It is shown that rescattering among secondaries can not
mimic the predicted correlation pattern expected for a Quark-Gluon-Plasma.
However, we find a strong increase of the C_BS correlation function with
decreasing collision energy both for pp and Au+Au/Pb+Pb reactions. For Au+Au
reactions at the top RHIC energy (\sqrt s=200 AGeV), the C_BS correlation is
constant for all centralities and compatible with the pp result. With
increasing width of the rapidity window, C_BS follows roughly the shape of the
baryon rapidity distribution. We suggest to study the energy and centrality
dependence of C_BS which allow to gain information on the onset of the
deconfinement transition in temperature and volume
Searching for the Critical Point of QCD: Theoretical Benchmark Calculations
We present a comprehensive study of event-by-event multiplicity fluctuations
in nucleon-nucleon and nucleus-nucleus interactions from AGS/FAIR to RHIC
energies within the UrQMD transport approach. The scaled variances of negative,
positive, and all charged hadrons are analysed. The scaled variance in central
Pb+Pb collisions increases with energy and behaves similar to inelastic p+p
interactions. We find a non-trivial dependence of multiplicity fluctuations on
the rapidity and transverse momentum interval used for the analysis and on the
centrality selection procedure. Quantitative predictions for the NA49
experiment are given, taking into account the acceptance of the detector and
the selection procedure of central events.Comment: 10 pages, 10 figure
- …