Chemical nonequilibrium and deconfinement in 200<i>A</i>GeV sulphur induced reactions

Letessier, Jean; Rafelski, Johann

doi:10.1103/physrevc.59.947

Cited by 62 publications

(74 citation statements)

References 33 publications

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“…This analysis addressed solely the strange particle abundances. When results for non-strange hadrons were included and were analyzed, it became necessary to expand the chemical-non-equilibrium approach, allowing the abundances of light quarks to vary [3,4]. In the analysis of the 158A GeV Pb collisions with Pb targets, we discovered that the light quark overabundance converged towards the maximum value allowed, at which point the entropy content of the final hadronic state is maximized [5].…”

Section: Historical Backgroundmentioning

confidence: 99%

Strangeness, equilibration, hadronization

Rafelski¹

2002

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

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Abstract. In these remarks I explain the motivation which leads us to consider chemical nonequilibrium processes in flavor equilibration and in statistical hadroniziation of quark-gluon plasma (QGP). Statistical hadronization allowing for chemical non-equilibrium is introduced. The reesults of fits to RHIC-130 results, including multistrange hadrons, are shown to agree only with the model of an exploding QGP fireball. Historical backgroundThe topic we discuss today, production of hadrons in statistical hadronization in high energy heavy ion collisions, has been the subject of several diploma and doctor thesis at the University Frankfurt in late 70's and early 80's. At the time, in a field void of any experimental result, I competed with a Hungarian hadrochemistry group lead by the chair of this discussion session, Prof. J. Zimanyi.We both passed through natural evolution stages. We were at first considering the equilibrium particle abundances expected to arise when Mr. EquilibriX holds in his hand hot and dense hadron matter fireball, which evaporated these particles. This work was followed by the development of kinetic theory of strangeness production, which was precipitated by the finding of the Budapest group, that light quark interactions were not fast enough to produce strangeness abundantly.We learned to appreciate that the yields of newly produced quarks were not necessarily given by the chemical equilibrium statistical model. The physics reason which lead us to explore the kinetic theory was relatively short available reaction time in relativistic heavy ion collisions, in general not allowing for the achievement of an equilibrium particle abundance. These remarks apply to the case that the dense matter fireball is made of hadrons, or deconfined quarks. Our work was extended to compare these two so different matter phases.This kinetic theory work has inspired the chemical non-equilibrium study of hadronization of quark-gluon plasma (QGP), and we were able to show that in a sudden hadronization process specific properties of QGP will be imparted in hadronization on particle yields. All these developments were then summarized in a relatively widely known theoretical review [1].When the first multistrange hadron experimental results arrived 10 years ago, the analysis applied introduced the chemical non-equilibrium [2], which then was generally accepted as being an important element of data analysis. This analysis addressed solely

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Section: Historical Backgroundmentioning

confidence: 99%

Strangeness, equilibration, hadronization

Rafelski¹

2002

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

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“…[73] for results involving most (as available) central collisions and heaviest nuclei. The solid circles are results obtained using the full SHM parameter set [7,[73][74][75][76][77][78][79]. The SHARE LHC freeze-out temperature is clearly below the lattice critical temperature range.…”

Section: Why Value Of T H Matters To Shm Analysis?mentioning

confidence: 99%

“…Thus gluon dissolution into additional hadrons assures that the light quark phase space occupancies as measured in terms of observed hadron abundances should show γ HG u,d > γ QGP u,d > 1. The introduction hadron-side of phase space occupancy γ s [65] and later γ u,d [79] into the study of hadron production in the statistical hadronization approach has been challenged. However there was no scientific case, challenges were driven solely by an intuitive argument that in RHI collisions at sufficiently high reaction energy aside of thermal, also chemical equilibrium is reached.…”

Section: Non-equilibrium In Fireball Hadronizationmentioning

confidence: 99%

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Melting hadrons, boiling quarks

Rafelski

2015

Eur. Phys. J. A

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Abstract. In the context of the Hagedorn temperature half-centenary I describe our understanding of the hot phases of hadronic matter both below and above the Hagedorn temperature. The first part of the review addresses many frequently posed questions about properties of hadronic matter in different phases, phase transition and the exploration of quark-gluon plasma (QGP). The historical context of the discovery of QGP is shown and the role of strangeness and strange antibaryon signature of QGP illustrated. In the second part I discuss the corresponding theoretical ideas and show how experimental results can be used to describe the properties of QGP at hadronization. The material of this review is complemented by two early and unpublished reports containing the prediction of the different forms of hadron matter, and of the formation of QGP in relativistic heavy ion collisions, including the discussion of strangeness, and in particular strange antibaryon signature of QGP.

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“…It has been suggested [53] that a similar parameter, γ q , should be included in thermal analyses to allow for deviations from equilibrium levels in the nonstrange sector. Furthermore, as collider energies increase, so does the need for the inclusion of charmed particles in the statistical-thermal model, with their occupation of phase-space possibly governed by an additional parameter, γ C .…”

Section: Deviations From Equilibrium Levelsmentioning

confidence: 99%

THERMUS—A thermal model package for ROOT

Wheaton

Cleymans

Hauer

2009

Computer Physics Communications

305

289

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THERMUS is a package of C++ classes and functions allowing statistical-thermal model analyses of particle production in relativistic heavy-ion collisions to be performed within the ROOT framework of analysis. Calculations are possible within three statistical ensembles; a grand-canonical treatment of the conserved charges B, S and Q, a fully canonical treatment of the conserved charges, and a mixedcanonical ensemble combining a canonical treatment of strangeness with a grandcanonical treatment of baryon number and electric charge. THERMUS allows for the assignment of decay chains and detector efficiencies specific to each particle yield, which enables sensible fitting of model parameters to experimental data. Nature of problem:Statistical-thermal model analyses of heavy-ion collision data require the calculation of both primordial particle densities and contributions from resonance decay. A set of thermal parameters (the number depending on the particular model imposed) and a set of thermalised particles, with their decays specified, is required as input to these models. The output is then a complete set of primordial thermal quantities for each particle, together with the contributions to the final particle yields from resonance decay.In many applications of statistical-thermal models it is required to fit experimental particle multiplicities or particle ratios. In such analyses, the input is a set of experimental yields and ratios, a set of particles comprising the assumed hadron resonance gas formed in the collision and the constraints to be placed on the system. The thermal model parameters consistent with the specified constraints leading to the best-fit to the experimental data are then output. Solution method:THERMUS is a package designed for incorporation into the ROOT [2] framework, used extensively by the heavy-ion community. As such, it utilises a great deal of ROOT's functionality in its operation. ROOT features used in THERMUS include its containers, the wrapper TMinuit implementing the MINUIT fitting package, and the TMath class of mathematical functions and routines. Arguably the most useful feature is the utilisation of CINT as the control language, which allows interactive 2 access to the THERMUS objects. Three distinct statistical ensembles are included in THERMUS, while additional options to include quantum statistics, resonance width and excluded volume corrections are also available. THERMUS provides a default particle list including all mesons (up to the K * 4 (2045)) and baryons (up to the Ω − ) listed in the July 2002 Particle Physics Booklet [3]. For each typically unstable particle in this list, THERMUS includes a text-file listing its decays. With thermal parameters specified, THERMUS calculates primordial thermal densities either by performing numerical integrations or else, in the case of the Boltzmann approximation without resonance width in the grand-canonical ensemble, by evaluating Bessel functions. Particle decay chains are then used to evaluate experimental observables...

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Chemical nonequilibrium and deconfinement in 200AGeV sulphur induced reactions

Cited by 62 publications

References 33 publications

Strangeness, equilibration, hadronization

Strangeness, equilibration, hadronization

Melting hadrons, boiling quarks

THERMUS—A thermal model package for ROOT

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