Experimental and theoretical challenges in the search for the quark-gluon plasma: The STAR Collaboration's critical assessment of the evidence from RHIC collisions
TL;DR: In this paper, the most important experimental results from the first three years of nucleus-nucleus collision studies at RHIC were reviewed, with emphasis on results of the STAR experiment.
About: This article is published in Nuclear Physics.The article was published on 2005-08-08 and is currently open access. It has received 2750 citations till now. The article focuses on the topics: Strangeness production & Quark–gluon plasma.
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TL;DR: In the most central Au+Au collisions at the highest beam energy, evidence is found for the formation of a very high energy density system whose description in terms of simple hadronic degrees of freedom is inappropriate as discussed by the authors.
1,786 citations
TL;DR: A brief history of the original Glauber model is presented in this article, with emphasis on its development into the purely classical, geometric picture used for present-day data analyses.
Abstract: We review the theoretical background, experimental techniques, and phenomenology of what is known in relativistic heavy ion physics as the Glauber model, which is used to calculate geometric quantities. A brief history of the original Glauber model is presented, with emphasis on its development into the purely classical, geometric picture used for present-day data analyses. Distinctions are made between the optical limit and Monte Carlo approaches, which are often used interchangeably but have some essential differences in particular contexts. The methods used by the four RHIC experiments are compared and contrasted, although the end results are reassuringly similar for the various geometric observables. Finally, several important RHIC measurements are highlighted that rely on geometric quantities, estimated from Glauber calculations, to draw insight from experimental observables. The status and future of Glauber modeling in the next generation of heavy ion physics studies is briefly discussed.
1,042 citations
Hampton University1, Thomas Jefferson National Accelerator Facility2, University of Paris-Sud3, University of Santiago, Chile4, Brookhaven National Laboratory5, University of Pavia6, University of Groningen7, Federico Santa María Technical University8, Shandong University9, Goethe University Frankfurt10, Stony Brook University11, Baruch College12, Duke University13, Argonne National Laboratory14, The Catholic University of America15, Old Dominion University16, Lawrence Berkeley National Laboratory17, Ohio State University18, University of Zagreb19, University of Jyväskylä20, Tel Aviv University21, CERN22, Temple University23, Massachusetts Institute of Technology24, Columbia University25, Ruhr University Bochum26, California Institute of Technology27, University of Massachusetts Amherst28, University of Buenos Aires29, University of the Basque Country30, University of Connecticut31, University of Tübingen32, Pennsylvania State University33, Stanford University34, Dalhousie University35, Central China Normal University36
TL;DR: In this article, the science case of an Electron-Ion Collider (EIC), focused on the structure and interactions of gluon-dominated matter, with the intent to articulate it to the broader nuclear science community, is presented.
Abstract: This White Paper presents the science case of an Electron-Ion Collider (EIC), focused on the structure and interactions of gluon-dominated matter, with the intent to articulate it to the broader nuclear science community. It was commissioned by the managements of Brookhaven National Laboratory (BNL) and Thomas Jefferson National Accelerator Facility (JLab) with the objective of presenting a summary of scientific opportunities and goals of the EIC as a follow-up to the 2007 NSAC Long Range plan. This document is a culmination of a community-wide effort in nuclear science following a series of workshops on EIC physics over the past decades and, in particular, the focused ten-week program on “Gluons and quark sea at high energies” at the Institute for Nuclear Theory in Fall 2010. It contains a brief description of a few golden physics measurements along with accelerator and detector concepts required to achieve them. It has been benefited profoundly from inputs by the users’ communities of BNL and JLab. This White Paper offers the promise to propel the QCD science program in the US, established with the CEBAF accelerator at JLab and the RHIC collider at BNL, to the next QCD frontier.
1,022 citations
TL;DR: A review of the theoretical background, experimental techniques, and phenomenology of what is called the "Glauber Model" in relativistic heavy ion physics is presented in this article, with emphasis on its development into the purely classical, geometric picture that is used for present-day data analyses.
Abstract: This is a review of the theoretical background, experimental techniques, and phenomenology of what is called the "Glauber Model" in relativistic heavy ion physics. This model is used to calculate "geometric" quantities, which are typically expressed as impact parameter (b), number of participating nucleons (N_part) and number of binary nucleon-nucleon collisions (N_coll). A brief history of the original Glauber model is presented, with emphasis on its development into the purely classical, geometric picture that is used for present-day data analyses. Distinctions are made between the "optical limit" and Monte Carlo approaches, which are often used interchangably but have some essential differences in particular contexts. The methods used by the four RHIC experiments are compared and contrasted, although the end results are reassuringly similar for the various geometric observables. Finally, several important RHIC measurements are highlighted that rely on geometric quantities, estimated from Glauber calculations, to draw insight from experimental observables. The status and future of Glauber modeling in the next generation of heavy ion physics studies is briefly discussed.
858 citations
TL;DR: In this article, the authors measured the charged-particle spectra at the BNL Relativistic Heavy Ion Collider (RHIC) time projection chamber and reported the average transverse momenta, total particle production, particle yield ratios, strangeness, and baryon production rates as a function of collision system and centrality.
Abstract: Identified charged-particle spectra of pi(+/-), K(+/-), p, and (p) over bar at midrapidity (vertical bar y vertical bar < 0.1) measured by the dE/dx method in the STAR (solenoidal tracker at the BNL Relativistic Heavy Ion Collider) time projection chamber are reported for pp and d + Au collisions at root s(NN) = 200 GeV and for Au + Au collisions at 62.4, 130, and 200 GeV. Average transverse momenta, total particle production, particle yield ratios, strangeness, and baryon production rates are investigated as a function of the collision system and centrality. The transverse momentum spectra are found to be flatter for heavy particles than for light particles in all collision systems; the effect is more prominent for more central collisions. The extracted average transverse momentum of each particle species follows a trend determined by the total charged-particle multiplicity density. The Bjorken energy density estimate is at least several GeV/fm(3) for a formation time less than 1 fm/c. A significantly larger net-baryon density and a stronger increase of the net-baryon density with centrality are found in Au + Au collisions at 62.4 GeV than at the two higher energies. Antibaryon production relative to total particle multiplicity is found to be constant over centrality, but increases with the collision energy. Strangeness production relative to total particle multiplicity is similar at the three measured RHIC energies. Relative strangeness production increases quickly with centrality in peripheral Au + Au collisions, to a value about 50% above the pp value, and remains rather constant in more central collisions. Bulk freeze-out properties are extracted from thermal equilibrium model and hydrodynamics-motivated blast-wave model fits to the data. Resonance decays are found to have little effect on the extracted kinetic freeze-out parameters because of the transverse momentum range of our measurements. The extracted chemical freeze-out temperature is constant, independent of collision system or centrality; its value is close to the predicted phase-transition temperature, suggesting that chemical freeze-out happens in the vicinity of hadronization and the chemical freeze-out temperature is universal despite the vastly different initial conditions in the collision systems. The extracted kinetic freeze-out temperature, while similar to the chemical freeze-out temperature in pp, d + Au, and peripheral Au + Au collisions, drops significantly with centrality in Au + Au collisions, whereas the extracted transverse radial flow velocity increases rapidly with centrality. There appears to be a prolonged period of particle elastic scatterings from chemical to kinetic freeze-out in central Au + Au collisions. The bulk properties extracted at chemical and kinetic freeze-out are observed to evolve smoothly over the measured energy range, collision systems, and collision centralities.
784 citations
References
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TL;DR: In this article, the main body of predictions of the theory for deep-inleastic scattering on either unpolarized or polarized targets is re-obtained by a method which only makes use of the simplest tree diagrams and is entirely phrased in parton language with no reference to the conventional operator formalism.
4,692 citations
TL;DR: In this paper, the temperature dependence of the screening radius, as obtained from lattice QCD, is compared with the J/ψ radius calculated in charmomium models, and the feasibility to detect this effect clearly in the dilepton mass spectrum is examined.
2,416 citations
TL;DR: In this paper, the space-time evolution of the hadronic matter produced in the central rapidity region in extreme relativistic nucleus-nucleus collisions is described, based on the existence of a flat central plateau and on the applicability of hydrodynamics.
Abstract: The space-time evolution of the hadronic matter produced in the central rapidity region in extreme relativistic nucleus-nucleus collisions is described. We find, in agreement with previous studies, that quark-gluon plasma is produced at a temperature &200— 300 MeV, and that it should survive over a time scale & 5 fm/c. Our description relies on the existence of a flat central plateau and on the applicability of hydrodynamics.
2,170 citations
TL;DR: It is argued that the distribution functions for quarks and gluons are computable at small {ital x} for sufficiently large nuclei, perhaps larger than can be physically realized, and that weak coupling methods may be used.
Abstract: We argue that the distribution functions for quarks and gluons are computable at small $x$ for sufficiently large nuclei, perhaps larger than can be physically realized. For such nuclei, we argue that weak coupling methods may be used. We show that the computation of the distribution functions can be recast as a many-body problem with a modified propagator, a coupling constant which depends on the multiplicity of particles per unit rapidity per unit area, and for non-Abelian gauge theories, some extra media-dependent vertices. We explicitly compute the distribution function for gluons to lowest order, and argue how they may be computed in higher order.
1,676 citations
TL;DR: A Monte Carlo event generator HIJING is developed to study jet and multiparticle production in high energy {ital pp, {ital pA}, and {ital AA} collisions, and a schematic mechanism of jet interactions in dense matter is described.
Abstract: Combining perturbative-QCD inspired models for multiple jet production with low ${p}_{T}$ multistring phenomenology, we develop a Monte Carlo event generator hijing to study jet and multiparticle production in high energy $\mathrm{pp}$, $\mathrm{pA}$, and $\mathrm{AA}$ collisions. The model includes multiple minijet production, nuclear shadowing of parton distribution functions, and a schematic mechanism of jet interactions in dense matter. Glauber geometry for multiple collisions is used to calculate $\mathrm{pA}$ and $\mathrm{AA}$ collisions. The phenomenological parameters are adjusted to reproduce essential features of $\mathrm{pp}$ multiparticle production data for a wide energy range ($\sqrt{s}=5\ensuremath{-}2000$ GeV). Illustrative tests of the model on $p+A$ and light-ion $B+A$ data at $\sqrt{s}=20$ GeV/nucleon and predictions for Au+Au at energies of the BNL Relativistic Heavy Ion Collider ($\sqrt{s}=200$ GeV/nucleon) are given.
1,180 citations