Violation of energy-per-hadron scaling in resonance matter

Bravina, L.; Faessler, Amand; Fuchs, Christian; Zabrodin, E.; Zhongdao, Lu

doi:10.1103/physrevc.66.014906

“…From the lowest at the GSI Schwerionen synchrotron (SIS) up to the highest energies at the BNL Relativistic Heavy Ion Collider (RHIC), all results on particle multiplicities are consistent with the assumption of chemical equilibrium in the final-state fireball produced after heavy-ion impact [1]. The particle yields are found to be described, with remarkable precision, by a thermal-statistical model that assumes approximate chemical equilibrium [1][2][3][4][5][6][7][8][9][10][11][12][13][14]17]. For a given collision energy, the thermal-statistical model with only two parameters, the temperature (T ) and baryon chemical potential (µ B ), provides a very systematic description of particle yields.…”

Section: Introductionsupporting

confidence: 51%

“…In order to have a consistent presentation, we have made some choices which are biased by our own experience: the code used in this paper is available for inspection [35]. Our analysis relies on the most recent results obtained in statistical-thermal model fits to Au + Au and Pb + Pb systems, performed by numerous groups over a wide range of energies [5][6][7][8][9][10][11][12][13][14]17]. These results are summarized in Table I and are also included in Fig.…”

Section: Global Descriptionmentioning

confidence: 99%

Comparison of chemical freeze-out criteria in heavy-ion collisions

Cleymans¹,

Oeschler²,

Redlich³

et al. 2007

Proceedings of Critical Point and Onset of Deconfinement — PoS(CPOD2006)

0

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One of the most remarkable results to emerge from heavy-ion collisions over the past two decades is the striking regularity shown by particle yields at all energies. This has led to several very successful proposals describing particle yields over a very wide range of beam energies, reaching from 1A GeV up to 200A GeV, using only one or two parameters. A systematic comparison of these proposals is presented here. The conditions of fixed energy per particle, baryon+anti-baryon density, normalized entropy density as well as percolation model are investigated. The results are compared with the most recent chemical freeze-out parameters obtained in the thermal-statistical analysis of particle yields. The sensitivity and dependence of the results on parameters is analyzed and discussed. It is shown that in the energy range above the top energy of the BNL Alternating Gradient Synchrotron within present accuracies, all chemical freeze-out criteria give a fairly good description of the particle yields. However, the low energy heavy-ion data favor the constant energy per particle as a unified condition of chemical particle freeze-out. This condition also shows the weakest sensitivity on model assumptions and parameters.

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“…Further evolution of the system is then due to the elastic collisions that substantially preserve the chemical composition of the collision in the fireball. The results from RHIC seems to favor a higher value for the energy per particle than that at SPS and lower energies [297]. This can be interpreted as a change in the baryonic composition of a two-component thermal source.…”

Section: Cleymans and Redlich: Constant Energy Per Particlementioning

confidence: 83%

Equilibrium statistical–thermal models in high-energy physics

Tawfik

¹

2014

Int. J. Mod. Phys. A

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We review some recent highlights from the applications of statistical-thermal models to different experimental measurements and lattice QCD thermodynamics, that have been made during the last decade. We start with a short review of the historical milestones on the path of constructing statistical-thermal models for heavy-ion physics. We discovered that Heinz Koppe formulated in 1948 an almost complete recipe for the statistical-thermal models. In 1950, Enrico Fermi generalized this statistical approach, in which he started with a general cross-section formula and inserted into it simplifying assumptions about the matrix element of the interaction process that likely reflects many features of the high-energy reactions dominated by density in the phase space of final states. In 1964, Hagedorn systematically analysed the high-energy phenomena using all tools of statistical physics and introduced the concept of limiting temperature based on the statistical bootstrap model. It turns to be quite often that many-particle systems can be studied with the help of statistical-thermal methods. The analysis of yield multiplicities in high-energy collisions gives an overwhelming evidence for the chemical equilibrium in the final state. The strange particles might be an exception, as they are suppressed at lower beam energies. However, their relative yields fulfil statistical equilibrium, as well. We review the equilibrium statistical-thermal models for particle production, fluctuations and collective flow in heavy-ion experiments. We also review their reproduction of the lattice QCD thermodynamics at vanishing and finite chemical potential. During the last decade, five conditions have been suggested to describe the universal behavior of the chemical freeze out parameters. The higher order moments of multiplicity have been discussed. They offer deep insights about particle production and to critical fluctuations. Therefore, we use them to describe the freeze out parameters and suggest the location of the QCD critical endpoint. Various extensions have been proposed in order to take into consideration the possible deviations of the ideal hadron gas. We highlight various types of interactions, dissipative properties and location-dependences (spacial rapidity). Furthermore, we review three models combining hadronic with partonic phases; quasi-particle model, linear σ-model with Polyakov-loop potentials and compressible bag model. PACS numbers: 12.40.Ee,24.60.-k,05.70.Fh,12.40.-y Keywords: Statistical models of strong interactions, Statistical physics of nuclear reactions, Phase transition in statistical mechanics and thermodynamics, Models of strong interactions Contents * http://atawfik.net/ † Electronic address: atawfik@cern.ch 65 3. Chiral phase transition 69 4. Confinement-deconfinement phase diagram 72 V. Higher order moments in statistical-thermal models 74 A. Non-normalized higher order moments 74 B. Normalized higher order moments 77 C. Products of higher order moments 78 D. Experimental higher order moments of particle yie...

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“…[12] that the results from RHIC favor a higher value for E / N . This was interpreted as a change in the baryonic composition of a two-component thermal source.…”

Section: Fixed E / N 1gevmentioning

confidence: 94%

Comparison of chemical freeze-out criteria in heavy-ion collisions

Cleymans

¹

,

Oeschler

²

,

Redlich

³

et al. 2006

View full text Add to dashboard Cite

One of the most remarkable results to emerge from heavy-ion collisions over the past two decades is the striking regularity shown by particle yields at all energies. This has led to several very successful proposals describing particle yields over a very wide range of beam energies, reaching from 1A GeV up to 200A GeV, using only one or two parameters. A systematic comparison of these proposals is presented here. The conditions of fixed energy per particle, baryon+anti-baryon density, normalized entropy density as well as percolation model are investigated. The results are compared with the most recent chemical freeze-out parameters obtained in the thermal-statistical analysis of particle yields. The sensitivity and dependence of the results on parameters is analyzed and discussed. It is shown that in the energy range above the top energy of the BNL Alternating Gradient Synchrotron within present accuracies, all chemical freeze-out criteria give a fairly good description of the particle yields. However, the low energy heavy-ion data favor the constant energy per particle as a unified condition of chemical particle freeze-out. This condition also shows the weakest sensitivity on model assumptions and parameters.

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Violation of energy-per-hadron scaling in resonance matter

Cited by 15 publications

References 35 publications

Comparison of chemical freeze-out criteria in heavy-ion collisions

Comparison of chemical freeze-out criteria in heavy-ion collisions

Equilibrium statistical–thermal models in high-energy physics

Comparison of chemical freeze-out criteria in heavy-ion collisions

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