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.
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 AGeV/c beam momentum. Results on Λ, Ξ and Ω ...hyperon yields at mid-rapidity in the most central 53% of Pb–Pb collisions at 40 AGeV/c are presented and compared with those obtained at higher energy, in the same collision centrality range.
The Λ and Ξ− yields per unit rapidity stay roughly constant while those of Ω−, Λ̄, Ξ̄+ and Ω̄+ increase when going to the higher SPS energy. Hyperon yields at the SPS are compared with those from the STAR experiment in sNN=130 GeV Au–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 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.
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
Recent results on strange baryons and antibaryon production in Pb-Pb collisions at 160 GeV per nucleon from the NA57 experiment are reported. Strangeness enhancements and the transverse mass spectra ...properties are described.
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/{\it c} and 40 A ...GeV/{\it c}. The value of $dN_{ch}/d\eta$ at the maximum has been determined and its behaviour as a function of centrality has been studied in the centrality range covered by NA57 (about 50% of the inelastic cross section). The multiplicity increases approximately logarithmically with the centre of mass energy.
The Na57 experiment has collected high statistics, high purity samples of K$^0_s$ and $\Lambda, \Xi $ and $\Omega$ hyperons produced in Pb-Pb collisions at 158 A GeV/c. In this paper we present a ...study of the transverse mass spectra of these particles for a sample of events corresponding to the most central 53 $\%$ of the inelastic Pb-Pb cross-section. We analyse the transverse mass distributions in the framework of the blast-wave model for the full sample and, for the first time at the SPS, as a function of the event centrality.
(NA57 Collaboration) F. Antinori,, A. Badala,, R. Barbera,, A. Belogianni, A. Bhasin, I. J. Bloodworth, G. E. Bruno,, S. A. Bull, R. Caliandro,, M. Campbell, W. Carena, N. Carrer, R. F. Clarke, A. ...Dainese,, A. P. de Haas,, P. C. de Rijke,, D. Di Bari,, S. Di Liberto,, R. Divia, D. Elia,, D. Evans, K. Fanebust, F. Fayazzadeh, J. Fedorisin, G. A. Feofilov, R. A. Fini,, J. Ftanik, B. Ghidini,, G. Grella,, H. Helstrup, M. Henriquez, A. K. Holme, A. Jacholkowski,, G. T. Jones, P. Jovanovic, A. Jusko, R. Kamermans,, J. B. Kinson, K. Knudson, A. A. Kolojvari, V. Kondratiev, I. Kralik, A. Kravcakova, P. Kuijer,, V. Lenti,, R. Lietava, G. Lovhoiden, M. Luptak, V. Manzari,, G. Martinska, M. A. Mazzoni,, F. Meddi,, A. Michalon, M. Morando,, D. Muigg,, E. Nappi,, F. Navach,, P. I. Norman, A. Palmeri,, G. S. Pappalardo,, B. Pastirak, J. Pisut, N. Pisutova, F. Posa,, E. Quercigh,, F. Riggi,, D. Rohrich, G. Romano,, K. afaik, L. andor, E. Schillings,, G. Segato,, M. Sene, R. Sene, W. Snoeys, F. Soramel,, M. Spyropoulou-Stassinaki, P. Staroba, T. A. Toulina, R. Turrisi,, T. S. Tveter, J. Urban, F. F. Valiev, A. van den Brink,, P. van den Ven,, P. Vande Vyvre, N. van Eijndhoven,, J. Van Hunen, A. Vascotto, T. Vik, O. Villalobos Baillie, L. Vinogradov, T. Virgili,, M. F. Votruba, J. Vrlakova, and P. Zavada Physics Department, Unversity of Athens, Athens, Greece Dipartimento IA di Fisica dell'Universita e del Politecnico di Bari, Bari, Italy INFN, Bari, Italy Fysik Institutt, Universitetet i Bergen, Bergen, Norway Hogskolen i Bergen, Bergen, Norway University of Birmingham, Birmingham, UK Comenius University, Bratislava, Slovakia University of Catania, Catania, Italy INFN, Catania, Italy CERN, European Laboratory for Particle Physics, Geneva, Switzerland Institute of Experimental Physics, Slovak Academy of Science, Koice, Slovakia P.J. afaik University, Koice, Slovakia Fysik Institutt, Universitetet i Olso, Oslo, Norway University of Padua, Padua, Italy INFN, Padua, Italy College de France, Paris, France Institute of Physics, Prague, Czech Republic University 'La Sapienza', Rome, Italy INFN, Rome, Italy Dipartimento di Scienze Fisiche 'E.R.Caianiello' dell'Universita, Salerno, Italy INFN, Salerno, Italy State University of St.Petersburg, St.Petersburg, Russia Institut de Recherche Subatomique, IN2P3/ULP, Strasbourg, France Utrecht University, Utrecht, The Netherlands NIKHEF, Utrecht, The Netherlands The production of strange baryons and anti-baryons in PbPb and pBe collisions has been studied by the NA57 experiment at the CERN SPS, extending down the centrality range covered by the previous WA97 experiment, and collecting data at two different energies. The enhanced production of such particles in central PbPb collisions with respect to pBe has been experimentally confirmed. This paper discusses results on and hyperon production obtained at 40 and 158 A GeV/c.
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