J. Pišút

An alternative mechanism of Jψ suppression in heavy ion collisions

Abstract We argue that J ψ suppression observed recently in high energy oxygen-uranium collisions by the NA38 Collaboration at CERN need not imply that the quark-gluon plasma was produced. A considerable part of the effect may be caused by the disintegration of J ψ s in collisions with dense hadronic matter (below the phase transition into quark-gluon plasma) produced simultaneously with J ψ in heavy ion interactions.

Rho-meson shape

Abstract A detailed description is developed for the invariant dipion mass distribution in the reaction π p → ππ N. Based on OPEM and modified phenomenologically this “generalized Breit-Wigner” formula accounts for peripheral production, t -dependence of the ϱ parameters, skewness of the ϱ peak, energy dependence of the ϱ width, energ-dependent departure from OPEM, background, and background interference. Contributions from other ππ partial waves are included and the possibility of ϱ being a CDD pole considered. The formula is used on a data compilation of large statistics and conclusions concerning the presence of the various terms and the ϱ parameters are reached. Finally, we compare the width of the pion-produced ϱ meson with the width of the e + e − produced ϱ meson.

An Alternative Mechanism of

Abstract We argue that J ψ suppression observed recently in high energy oxygen-uranium collisions by the NA38 Collaboration at CERN need not imply that the quark-gluon plasma was produced. A considerable part of the effect may be caused by the disintegration of J ψ s in collisions with dense hadronic matter (below the phase transition into quark-gluon plasma) produced simultaneously with J ψ in heavy ion interactions.

J/\psi

Abstract We point out that recent indications from the NA38 Collaboration for an increase of the φ/(ω+ϱ0) ratio in central 200A GeV O+U and S+U collisions at CERN give evidence for an approach to chemical equilibrium in these systems. Under the assumption (which is supported by previous theoretical work) that the J/ψ suppression found in the same experiment under similar kinematic conditions is due to final state absorption via rescattering in the dense collision zone, we solve the rate equations for φ-production and -absorption via secondary collisions in the reaction zone. Eliminating unknown geometrical parameters of the collision zone by using the J/ψ suppression data, we obtain a quantitative description of the measured φ enhancement.

Suppression in Heavy Ion Collisions

A measurement of strange baryon and antibaryon production in Pb-Pb collisions has been carried out by the NA57 experiment at the CERN SPS, with 40 and 158 A GeV/c beam momentum. Results on

φ-enhancement and J/ψ suppression in nuclear collisions by rescattering of secondary hadrons

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Energy dependence of hyperon production in nucleus–nucleus collisions at SPS

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On the transverse energy distributions in the central rapidity region of 16O+Pb collisions at 200 GeV per nucleon

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On the time dependence of J/ψ suppression by the quark-gluon plasma

and

A clear-cut test of low mass dilepton production mechanism in hadronic collisions

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