Predictions for the LHC heavy-ion program

“…The data suggest a nearly boost-invariant region that is several units wide for central events but considerably smaller for peripheral ones. It has been noted [89] that if the QCD matter produced at midrapidity at RHIC is in local equilibrium, then deviations from the triangular shape of v 2 (η) observed in the PHOBOS measurements [41] would be expected around midrapidity at LHC energies. Detailed comparisons of theoretical calculations to the results presented here can give new insights into the nature of the matter produced at both RHIC and LHC energies.…”

Section: Discussionmentioning

confidence: 99%

Measurement of the elliptic anisotropy of charged particles produced in PbPb collisions atsNN=2.76TeV

Chatrchyan¹,

Khachatryan²,

Sirunyan³

et al. 2013

Phys. Rev. C

230

157

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The anisotropy of the azimuthal distributions of charged particles produced in √ s NN = 2.76 TeV PbPb collisions is studied with the CMS experiment at the LHC. The elliptic anisotropy parameter, v 2 , defined as the second coefficient in a Fourier expansion of the particle invariant yields, is extracted using the event-plane method, two-and four-particle cumulants, and Lee-Yang zeros. The anisotropy is presented as a function of transverse momentum (p T ), pseudorapidity (η) over a broad kinematic range, 0.3 < p T < 20 GeV/c, |η| < 2.4, and in 12 classes of collision centrality from 0 to 80%. The results are compared to those obtained at lower center-of-mass energies, and various scaling behaviors are examined. When scaled by the geometric eccentricity of the collision zone, the elliptic anisotropy is found to obey a universal scaling with the transverse particle density for different collision systems and center-of-mass energies.

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“…Simple extrapolations [48,49] of the collision energy dependence of v 2 look rather "reliable'. Note that there exist calculations predicting decrease of the elliptic flow [50].…”

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confidence: 99%

Anisotropic flow: achievements, difficulties and expectations

Voloshin¹

2008

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

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Abstract. Anisotropic flow measurements play a crucial role in understanding the physics and bulk properties of the system created in heavy ion collisions. In this talk I briefly review the most important results obtained so far, recent developments in the analysis techniques and the interpretation of the results, and what should we expect next, both at RHIC and LHC. I also discuss event anisotropies sensitive to the strong parity violation effects.Analysis of the event anisotropies (anisotropic flow) in multiparticle production in non-central nuclear collisions appeared to be one of the most informative paths in understanding the physics and characterizing the properties of the dense and hot strongly interacting medium. It has been observed a continuous increase in the value of in-plane elliptic flow (v 2 > 0) [1] from the top AGS energies to RHIC. At RHIC, strong elliptic flow [2] comparable in strength to the predictions of ideal hydrodynamics, and the hadronization via quark coalescence following from constituent quark number scaling of differential flow [3,4], together with the jet quenching, are the key ingredients in the picture of sQGP (strongly coupled Quark Gluon Plasma).The field is rapidly developing and evolving. From the "discovery phase" of the first years of RHIC operations it has been transforming into detailed quantitative description of the sQGP phase and subsequent hadronization. The plots of v 2 /ε vs particle density [3,5,6] that have been extensively used in the assessment of the level of thermalization reached in the relativistic nuclear collisions and applicability of ideal hydrodynamics comes under scrutiny: are the measurements of elliptic flow precise enough, are the anisotropies what we think they are and how much are they modified by fluctuation processes? When comparing to hydrodynamical calculations, are the proper initial conditions used in the calculations? Could it be that we have missed some important physics building the models? In the last couple years significant progress has been reached answering each and every of these questions. The role of viscosity, flow fluctuations, initial conditions (eccentricity and initial flow (velocity) field) are a few questions to report in this review. I also discuss preliminary measurements of azimuthal "out-of-plane" anisotropies that are related to one of the fundamental questions of the strong parity violation. Finally, I briefly overview future measurements at RHIC and arXiv:0805.1351v1 [nucl-ex]

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Predictions for the LHC heavy-ion program

Abstract: Apparently universal trends have been observed in relativistic nucleusnucleus collisions up to RHIC energies. Here, we review these trends and we discuss their agnostic extrapolation to heavy ion collisions at the LHC.

Cited by 24 publications

References 186 publications

Collective Phenomena in Non-Central Nuclear Collisions

Collective Phenomena in Non-Central Nuclear Collisions

Measurement of the elliptic anisotropy of charged particles produced in PbPb collisions atsNN=2.76TeV

Anisotropic flow: achievements, difficulties and expectations

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