Ω− signal in WA85

Abatzis, S.; Andrighetto, A.; Barnes, R. P.; Bayes, A. C.; Benayoun, M.; Beusch, W.; Bravar, A.; Carney, J. N.; Cruz, B. De La; Bari, D. Di; Dufey, J.P.; Davies, J.; Elia, D.; Evans, D.; Fini, R. A.; French, B. R.; Ghidini, B.; Girone, M.; Helstrup, H.; Holme, A.K.; Jachołkowski, A.; Kahane, J.; Kinson, J.B.; Kirk, A.; Knudson, K.; Lassalle, J. C.; Lenti, V.; Manzari, V.; Navach, F.; Narjoux, J. L.; Penzo, A.; Quercigh, E.; Rossi, L. P.; Šafařı́k, K.; Sené, M.; Sené, R.; Vassiliadis, G.; Baillie, O. Villalobos; Volte, A.; Votruba, M.F.

doi:10.1016/0375-9474(94)90676-9

Cited by 23 publications

(33 citation statements)

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“…The ratiosΛ/Λ,Ξ/Ξ, Ξ/Λ andΞ/Λ measured by the WA85 and WA97 collaborations [295,296,297] at the SPS can be fit in analogy to the ratios at the AGS by an equilibrium hadron gas model with γ s = 0.7, µ B = 0.24 and T = 180 MeV [154]. Besides the three parameters T, µ B and µ S which are used in the grand-canonical formalism of statistical mechanics, the additional parameter γ s accounts for incomplete saturation of strange particles in phase space.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore K + /K − ,Λ/Λ andp/p production ratios have been measured at the AGS [140]. At the SPS, enhanced production of (anti)hyperons, such asΛ,Ξ, Ω andΩ, has been observed and ratios ofΛ/Λ,Ξ/Ξ, Ξ/Λ andΞ/Λ have been analyzed by the NA36,WA85 and WA97 collaborations [293,294,295,296,297,298,299,300]. The WA94 collaboration has measured antihyperon ratios (i.e.…”

Section: Experimental Statusmentioning

confidence: 99%

See 1 more Smart Citation

Signatures of quark-gluon plasma formation in high energy heavy-ion collisions: a critical review

Bass

Gyulassy

Stöcker

et al. 1999

J. Phys. G: Nucl. Part. Phys.

280

223

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A critical review on signatures of quark-gluon plasma (QGP) formation is given and the current (1998) experimental status is discussed. After giving an introduction to the properties of QCD matter in both, equilibrium and non-equilibrium theories, we focus on observables which may yield experimental evidence for QGP formation. For each individual observable the discussion is divided into three sections: first the connection between the respective observable and QGP formation in terms of the underlying theoretical concepts is given, then the relevant experimental results are reviewed and finally the current status concerning the interpretation of both, theory and experiment, is discussed. A comprehensive summary including an outlook towards RHIC is given in the final section.

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Section: Discussionmentioning

confidence: 99%

Section: Experimental Statusmentioning

confidence: 99%

Signatures of quark-gluon plasma formation in high energy heavy-ion collisions: a critical review

Bass

Gyulassy

Stöcker

et al. 1999

J. Phys. G: Nucl. Part. Phys.

280

223

View full text Add to dashboard Cite

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“…This fact is important for numerical calculations but was not taken into account in previous publications. Note also that at small densities and equal particle volume parameters, v i = v, our [13] (3) is very close to the inconsistent formulation [4,5,6] with…”

mentioning

confidence: 83%

“…We begin our calculations with WA85 experimental data for strange baryon ratios in S-W collisions [13], namelȳ…”

mentioning

confidence: 99%

The excluded volume hadron gas model and pion production at the SPS

Ritchie

Gorenstein

Miller

1997

Zeitschrift f�r Physik C Particles and Fields

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Experimental data for nucleus-nucleus collisions at the CERN SPS suggest that an ideal hadron gas model is unable to account simultaneously (same baryonic chemical potential and temperature at freeze-out) for the strange anti-baryon to baryon ratios and pion abundances. Using a thermodynamically consistent excluded volume model we examine possibilities to account for the observed excess of pions.The formation of systems at high energies and densities allows the study of matter in another regime which, it is hoped, is amenable to the use of equilibrium statistical physics. Of particular interest is the possibility for the formation of a short-lived phase transition to a quark-gluon plasma (QGP). Recently nucleus-nucleus collisions have been performed at the BNL AGS (14 A GeV) and the CERN SPS (200 A GeV) producing energetic systems in which such a phase transition is hoped to take place. However, it is first necessary to understand predictions from conventional hadron physics before one can draw conclusions about any new phenomena which may be observed.Assuming local thermodynamical equilibrium at the final (freeze-out) stage of the process, particle number ratios can be calculated without detailed knowledge of the very complicated and poorly understood dynamics of heavy ion collisions. Strange particle production has attracted special attention as a possible signal of QGP formation [1, 2]. Hadron gas models have been successful in reproducing many of the observed hadron ratios measured at the AGS and SPS [3,4,5,6,7,8]. However for SPS data it has been observed [9, 4, 5, 6] that a simple ideal gas model is unable, within a single set of freeze-out parameters, to simultaneously yield the strange anti-baryon to baryon ratios together with pion to proton and charged particle ratios D Q = (N + − N − )/(N + + N − ) (N + and N − are the positive and negative charged hadron multiplicities). Note that N + − N − ∼ = p, N − ∼ = π − (p, π − are proton and negative pion multiplicities) and hence D Q ∼ = (1 + 2π − /p) −1 . It appears that the chemical freeze-out values of temperature T and baryonic chemical potential µ b found in Refs. [9,4,5,6] from the SPS data for strange particles are in a contradiction with the large pion/nucleon ratio. As D Q can be related to the entropy of the system, hadron gas models appear unable to account for the large entropy per baryon at freeze-out [9]. Therefore, unexpectedly, not strange particles but the deficiency of pions in the hadron gas model calculations is the main problem in the theoretical hadron gas interpretation of the SPS particle production data. Several mechanisms of the two-stage hadron chemical freeze-out [5] and QGP breakup to hadrons [9,5] have been proposed to remedy this problem but without significant success.The large values of T and µ b found in hadron gas models suggest that the chemical freeze-out state in the SPS experiments looks rather like a hot dense hadron gas and one needs a non-ideal gas equation of state to describe the system. In Refs. [7,8] a non-ideal fo...

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“…However, measurements of hyperons and antihyperons also provide us with valuable information on primordial yield ratios resulting from partonic coalescence essentially free of reequilibration in the subsequent hadronic expansion phase. The measurements were made by the WA85 collaboration for S+W at 200 GeV/nucleon [13], and an analysis was performed [14] in which various yield ratios describe curves of allowed Hagedorn model solutions in a plane of temperature, T, and baryochemical potential, pg. The curves were found to intersect at about T = 185 MeV and pg = 0.24 GeV.…”

Section: Expansion Hadronization and Freeze-outmentioning

confidence: 99%