Vacuum pressure effects in low-p⊥ hadronic spectra

Shuryak, Edward; Zhirov, O. V.

doi:10.1016/0370-2693(80)90023-4

Cited by 87 publications

(67 citation statements)

References 16 publications

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“…(Long discussion afterwords shown that ideal hydro is not really applicable in this case, however.). Zhirov and myself [10] found no flow in pp data from ISR: the π, K.N spectra from pp showed the same m t -slope. All of us had to wait for heavy ion collisions at high energies, and only at SPS and now at RHIC we have seen real hydrodynamical flow, radial and especially elliptic.…”

Section: Transverse Flowmentioning

confidence: 92%

What RHIC experiments and theory tell us about properties of quark–gluon plasma?

2005

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This brief review summarizes the main experimental discoveries made at RHIC and then discusses their implications. The robust collective flow phenomena are well described by ideal hydrodynamics, with the Equation of State (EoS) predicted by lattice simulations. However the transport properties turned out to be unexpected, with rescattering cross section one-to-two orders of magnitude larger than expected from perturbative QCD. These and other theoretical developments indicate that Quark-Gluon Plasma (QGP) produced at RHIC, and probably in a wider temperature region T c < T < 4T c , is not at all a weakly coupled quasiparticle gas, but is rather in a strongly coupled regime, sQGP for short. After reviewing two other "strongly coupled systems", (i) the strongly coupled supersymmetric theories studied via Maldacena duality; (ii) trapped ultracold atoms with very large scattering length, we return to sQGP and show that there should exist literally hundreds of bound states in it in the RHIC domain, most them colored. We then discuss recent ideas of their effect on the EoS, viscosity and jet quenching.

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Section: Transverse Flowmentioning

confidence: 92%

What RHIC experiments and theory tell us about properties of quark–gluon plasma?

2005

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“…In p 1 p collisions, the density of produced particles is low, insufficient to produce an appreciable collective flow. Therefore, the slope parameters show no dependence on the particle mass [25,26]. Conversely, for heavy colliding systems the density of produced particles is rather high, giving rise to significant rescattering, and thus collective transverse motion.…”

mentioning

confidence: 94%

Collective Expansion in High Energy Heavy Ion Collisions

Bearden¹,

Bøggild²,

Boissevain³

et al. 1997

Phys. Rev. Lett.

225

115

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Transverse mass spectra of pions, kaons, and protons from the symmetric heavy-ion collisions 200A GeV S 1 S and 158A GeV Pb 1 Pb, measured in the NA44 focusing spectrometer at CERN, are presented. The mass dependence of the slope parameters provides evidence of collective transverse flow from expansion of the system in heavy-ion induced central collisions. The purpose of studying ultrarelativistic heavy-ion collisions is to understand the nature of hadronic matter under extreme conditions. Specifically, we are interested in a new form of matter, quark-gluon plasma, which may be produced in such collisions. Transverse momentum distributions are one of the most common tools used in studying high energy collisions. This is because the transverse motion is generated during the collision and hence is sensitive to the dynamics. More than 45 years ago, Fermi proposed a statistical method [1] to understand the results of high energy hadron-hadron collisions. Because of saturation of the phase space, the multiparticle production resulting from the high energy elementary collisions is consistent with a thermal description [1][2][3]. In heavy-ion collisions hydrodynamical behavior, that is, local thermal equilibrium and collective motion, may be expected because of the large number of secondary scatterings.It is now possible to identify and quantitatively measure the collective motion by systematic studies of results from different collision systems, using light (Si at BNL and S at CERN) and heavy (Au at BNL and Pb at CERN) ion beams [4][5][6]. A high degree of nuclear stopping and a strong Coulomb effect (also due to the high stopping) have already been reported in Pb 1 Pb central collisions [7,8]. In this Letter, we present transverse momentum distributions of pions, kaons, and protons, measured in the NA44 spectrometer, from Pb 1 Pb and S 1 S collisions. Results of calculations from a hydrodynamical model [5] will be used to aid in this analysis.The NA44 magnetic focusing spectrometer consists of two room-temperature dipoles and three superconducting quadruples. Particles originating from the target are focused at a plane about ten meters downstream and detected by a tracking system consisting of a pad chamberstrip chamber-scintillator hodoscope complex. Particle identification is done with two threshold Cherenkov counters and two highly segmented TOF hodoscopes. The phase-space coverage (transverse momentum p T vs rapidity y) is determined by the combination of the spectrometer angle (relative to the beam direction) and the nominal momentum setting of the magnets. The momentum resolution is typically s p ͞p # 0.2% and the TOF counters have an average time resolution of 100 ps. More details of the spectrometer can be found elsewhere [9].The spectrometer momentum range is 620% around the nominal values of 4 and 8 GeV͞c. For kaons and protons, the 8 GeV͞c setting was used and the rapidity coverage is (2.5-3.4) and (2.4-2.8) for kaons and protons, respectively. Two angular settings (44 and 130 mrad) were utilized in order ...

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“…Many years ago, in a prehistoric era before QCD, I have tried to apply hydro to e + e − : discovery of jets several years later put the end to it. Also in 1970's, a search for signs of transverse flow in the early hadronic spectra at CERN ISR from pp collisions was performed by (my former student) Zhirov and myself [5] have found little or no signs of the collective transverse flow. Apparent lack of collectivity in pp or e + e − shows that although they also produce a multi-body excited systems, those are not macroscopically large.…”

Section: Is Hadronic Matter Really Produced In Heavy Ion Collisions?mentioning

confidence: 99%

Why does the quark–gluon plasma at RHIC behave as a nearly ideal fluid?

Shuryak¹

2004

Progress in Particle and Nuclear Physics

405

176

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The lecture is a brief review of the following topics: (i) collective flow phenomena in heavy ion collisions. The data from RHIC indicate robust collective flows, well described by hydrodynamics with expected Equation of State. The transport properties turned out to be unexpected, with very small viscosity; (ii) physics of highly excited matter produced in heavy ion collisions at T c < T < 4T c is different from weakly coupled quark-gluon plasma because of relatively strong coupling generating bound states of quasiparticles; (iii) wider discussion of other "strongly coupled systems" including strongly coupled supersymmetric theories studied via Maldacena duality, as well as recent progress in trapped atoms with very large scattering length.

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Vacuum pressure effects in low-p⊥ hadronic spectra

Cited by 87 publications

References 16 publications

What RHIC experiments and theory tell us about properties of quark–gluon plasma?

What RHIC experiments and theory tell us about properties of quark–gluon plasma?

Collective Expansion in High Energy Heavy Ion Collisions

Why does the quark–gluon plasma at RHIC behave as a nearly ideal fluid?

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