We propose a simple Glauber-type mechanism for the suppression of jet production up to transverse momenta of about 10 \(\mathrm {GeV}/c\) at RHIC. For processes in this kinematic region, the ...formation time is smaller than the interval between two successive hard partonic collisions and the subsequent collision influences the jet production. The number of jets then roughly scales with the number of participants. Proportionality to the number of binary collisions is recovered for very high transverse momenta. The model predicts suppression of jet production in \(d + {\mathrm {Au}}\) collisions at RHIC.
We present a few estimates of energy densities reached in heavy-ion collisions at the CERN SPS. The estimates are based on data and models of proton-nucleus and nucleus-nucleus interactions. In all ...of these estimates the maximum energy density in central Pb+Pb interactions is larger than the critical energy density \(\varepsilon_c\approx 0.7 \)GeV/fm3 following from lattice gauge theory computations. In estimates which we consider as realistic the maximum energy density is about \(2\varepsilon_c\). In this way our analysis gives some support to claims that deconfined matter has been produced at the CERN SPS. Any definite statement requires a deeper understanding of formation times of partons and hadrons in nuclear collisions. We also compare our results with implicit energy estimates contained in earlier models of anomalous \(J/\psi\) suppression in nuclear collisions.
The multiplicity of charged particles in the central rapidity region has been measured by the NA57 experiment in Pb–Pb collisions at the CERN SPS at two beam momenta: 158 A GeV/c and 40 A GeV/c. The ...value of dNch/dη at the maximum has been determined and studied as a function of centrality within the range covered by NA57 (about 55 most central part of the inelastic cross section). The central rapidity multiplicity varies roughly linearly with the number of wounded nucleons (participants) and increases approximately logarithmically with the centre of mass energy.
Status of the NA57 experiment at CERN SPS Manzari, V; Collaboration, the NA57; Antinori, F ...
Journal of physics. G, Nuclear and particle physics,
03/2001, Letnik:
27, Številka:
3
Journal Article
The data of J/psi suppression at large x(F) in pA collisions are used to infer the existence of gluon depletion as the projectile proton traverses the nucleus. The modification of the gluon ...distribution is studied by use of a convolution equation whose nonperturbative splitting function is determined phenomenologically. The depletion factor at x(1) = 0.8 is found to be about 25% at A = 100.
We point out that formation time of pions produced in heavy ion collisions modifies the mass spectrum of dileptons produced via
π
+
π
− →
e
+
e
−. Increasing formation time enhances the production of ...dileptons with lower masses. The effect offers an explanation of a part of the enhanced production of dileptons below the ϱ-meson mass as observed by the CERES and HELIOS Collaborations at the CERN SPS.
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