H. Stöcker

Nuclei in a chiral SU(3) model

Nuclei can be described satisfactorily in a nonlinear chiral SU(3)-framework, even with standard potentials of the linear

Statistical Coalescence Model with Exact Charm Conservation

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Collective Flow Signals the Quark-Gluon Plasma

-model. The condensate value of the strange scalar meson is found to be important for the properties of nuclei even without adding hyperons. By neglecting terms which couple the strange to the nonstrange condensate one can reduce the model to a Walecka model structure embedded in SU(3). We discuss inherent problems with chiral SU(3) models regarding hyperon optical potentials.

Chiral Lagrangian for strange hadronic matter

The statistical coalescence model for the production of open and hidden charm is considered within the canonical ensemble formulation. The data for the J/ multiplicity in Pb+Pb collisions at 158 AGeV are used for the model prediction of the open charm yield which has not yet been measured in these reactions. The charmonium states J/ andhave been measured in nucleus-nucleus (A+A) collisions at CERN SPS over the last 15 years by the NA38 and NA50 Collaborations. This experimental program was motivated by a suggestion (1) to use the J/ as a probe of the state of matter created in the early stage of the collision. In this approach a significant suppression of J/ production relative to Drell-Yan lepton pairs is predicted when going from peripheral to central Pb+Pb interactions at 158 AGeV. This is originally attributed to the formation of a quark-gluon plasma, but could be also explained in microscopic hadron models as secondary collision effects (see (2) and references therein). The statistical approach, formulated in Ref.(3), assumes that J/ mesons are created at hadronization according to the available hadronic phase-space. In this model the J/ yield is independent of the open charm yield. The model offers a natural explanation of the proportionality of the J/ and pion yields and the magnitude of the J/ multiplicity in hadronic and nuclear collisions. Recently the statistical coalescence model (4) and the microscopical coalescence model (5) were introduced for the charmonium production. Similar to the statistical model (3), the charmonium states are assumed to be formed at the hadronization stage. However, they are produced as a coalescence of created earlier c-c quarks and therefore the multi- plicities of open and hidden charm hadrons are connected in the coalescence models. In Ref. (4) the charm quark-antiquark pairs are assumed to be created at the early stage of A+A collision and the average number of c-c pairs, N dir cc , is fixed by the model consid- eration based on the hard scattering approach. The estimated number N dir

Azimuthal correlations of pions in relativistic heavy ion collisions at 1-GeV/nucleon

A critical discussion of the present status of the CERN experiments on hadron collective flow is given. We emphasize the importance of the flow excitation function from 1 to 50 A·GeV: here the hydrodynamic model has predicted the collapse of the ]]> v_1

Colour rope formation and strange baryon production in ultrarelativistic heavy ion collisions

flow and of the v2 flow at ∼10 A·GeV; at 40 A·GeV it has been recently observed by the NA49 Collaboration. Since hadronic rescattering models predict much larger flow than observed at this energy we interpret this observation as potential evidence for a first order phase transition at high baryon density ρB. A detailed discussion of the collective flow as a barometer for the equation of state (EoS) of hot dense matter at RHIC follows. Here, hadronic rescattering models can explain 2 GeV/c. This is interpreted as evidence for the production of superdense matter at RHIC with initial pressure far above hadronic pressure, p > 1 GeV/fm3. We suggest that the fluctuations in the flow, v1 and v2, should be measured in future since ideal hydrodynamics predicts that they are larger than 50% due to initial state fluctuations. Furthermore, the QGP coefficient of viscosity may be determined experimentally from the fluctuations observed.

Kaon production at subthreshold energies

A generalized Lagrangian for the description of hadronic matter based on the linear

Mach shocks induced by partonic jets in expanding quark–gluon plasma

\mathrm{SU}{(3)}_{L}\ifmmode\times\else\texttimes\fi{}\mathrm{SU}{(3)}_{R}

Hypernuclei, dibaryon and antinuclei production in high energy heavy ion collisions: Thermal production vs. Coalescence ✩

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