Review of the results of the KaoS Collaboration

Foerster, A.; Boettcher, I.; Dohrmann, F.; Grosse, E.; Koczoń, P.; Kohlmeyer, B.; Lang, S.; Laue, F.; Menzel, Matthias; Naumann, L.; Oeschler, H.; Płoskoń, M.; Puehlhofer, F.; Scheinast, W.; Schmah, A.; Schuck, Tanja; Schwab, E.; Senger, P.; Shin, Y.; Stroebele, H.; Sturm, C.; Uhlig, F.; Wagner, A.; Waluś, W.; KaoS-Collaboration,

doi:10.1088/0954-3899/31/6/009

Cited by 56 publications

(116 citation statements)

References 28 publications

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“…The question remains whether the discrepancies shown in Fig. 2 [21]. As argued in [13] the different slopes could be traced back to repulsive potentials of kaons with nucleons, which lead to a hardening of the K + spectra, and attractive antikaon-nucleon potentials, which lead to a softening of the K − spectra.…”

mentioning

confidence: 78%

Evidence for Nonhadronic Degrees of Freedom in the Transverse Mass Spectra of Kaons from Relativistic Nucleus-Nucleus Collisions?

Bratkovskaya

Soff²,

Stöcker³

et al. 2004

Phys. Rev. Lett.

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We investigate transverse hadron spectra from relativistic nucleus-nucleus collisions which reflect important aspects of the dynamics -such as the generation of pressure -in the hot and dense zone formed in the early phase of the reaction. Our analysis is performed within two independent transport approaches (HSD and UrQMD) that are based on quark, diquark, string and hadronic degrees of freedom. Both transport models show their reliability for elementary pp as well as light-ion (C+C, Si+Si) reactions. However, for central Au+Au (Pb+Pb) collisions at bombarding energies above ∼ 5 A·GeV the measured K ± transverse mass spectra have a larger inverse slope parameter than expected from the calculation. Thus the pressure generated by hadronic interactions in the transport models above ∼ 5 A·GeV is lower than observed in the experimental data. This finding shows that the additional pressure -as expected from lattice QCD calculations at finite quark chemical potential and temperature -is generated by strong partonic interactions in the early phase of central Au+Au (Pb+Pb) collisions. The phase transition from partonic degrees of freedom (quarks and gluons) to interacting hadrons is a central topic of modern high-energy physics. In order to understand the dynamics and relevant scales of this transition laboratory experiments under controlled conditions are presently performed with ultra-relativistic nucleusnucleus collisions. Hadronic spectra and relative hadron abundancies from these experiments reflect important aspects of the dynamics in the hot and dense zone formed in the early phase of the reaction. Furthermore, as has been proposed early by Rafelski and Müller [1] the strangeness degree of freedom might play an important role in distinguishing hadronic and partonic dynamics.

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confidence: 78%

Evidence for Nonhadronic Degrees of Freedom in the Transverse Mass Spectra of Kaons from Relativistic Nucleus-Nucleus Collisions?

Bratkovskaya

Soff²,

Stöcker³

et al. 2004

Phys. Rev. Lett.

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“…If the K − /K + multiplicity ratio is plotted as a function of the beam energy for the inclusive data and for various systems measured by KaoS [15,47], as shown in Fig. 11, one can see that the ratio increases with beam energy and that the HADES data point fits nicely into the energy systematics.…”

Section: Discussionmentioning

confidence: 99%

ϕ decay: A relevant source forK−production at energies available at the GSI Schwerionen-Synchrotron (SIS)?

Agakishiev¹,

Bałanda²,

Bannier³

et al. 2009

Phys. Rev. C

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“…In fact, the m T slopes of kaons and antikaons at SIS energies (1.5 to 2 A·GeV) were found to differ significantly [34]. As argued in [15] the different slopes could be traced back to repulsive kaon- nucleon potentials, which lead to a hardening of the K + spectra, and attractive antikaon-nucleon potentials, which lead to a softening of the K − spectra.…”

mentioning

confidence: 85%

Review of QGP Signatures — Ideas Versus Observables

Bratkovskaya

Bleicher

Dumitru

et al. 2004

Structure and Dynamics of Elementary Matter

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We investigate hadron production and transverse hadron spectra in nucleus-nucleus collisions from 2 A·GeV to 21.3 A·TeV within two independent transport approaches (UrQMD and HSD) based on quark, diquark, string and hadronic degrees of freedom. The enhancement of pion production in central Au+Au (Pb+Pb) collisions relative to scaled pp collisions (the 'kink') is described well by both approaches without involving a phase transition. However, the maximum in the K + /π + ratio at 20 to 30 A·GeV (the 'horn') is missed by ∼ 40%. Also, at energies above ∼ 5 A·GeV, the measured K ± mT -spectra have a larger inverse slope than expected from the models. Thus the pressure generated by hadronic interactions in the transport models at high energies is too low. This finding suggests that the additional pressure -as expected from lattice QCD at finite quark chemical potential and temperature -might be generated by strong interactions in the early pre-hadronic/partonic phase of central heavy-ion collisions. Finally, we discuss the emergence of density perturbations in a first-order phase transition and why they might affect relative hadron multiplicities, collective flow, and hadron mean-free paths at decoupling. A minimum in the collective flow v2 excitation function was discovered experimentally at 40 A·GeV -such a behavior has been predicted long ago as signature for a first order phase transition.

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Review of the results of the KaoS Collaboration

Cited by 56 publications

References 28 publications

Evidence for Nonhadronic Degrees of Freedom in the Transverse Mass Spectra of Kaons from Relativistic Nucleus-Nucleus Collisions?

Evidence for Nonhadronic Degrees of Freedom in the Transverse Mass Spectra of Kaons from Relativistic Nucleus-Nucleus Collisions?

ϕ decay: A relevant source forK−production at energies available at the GSI Schwerionen-Synchrotron (SIS)?

Review of QGP Signatures — Ideas Versus Observables

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