Table of contents

The Quark Matter 2006 conference was held on 14–20 November 2006 at the Shanghai Science Hall of the Shanghai Association of Sciences and Technology in Shanghai, China. It was the 19th International Conference on Ultra-Relativistic Nucleus–Nucleus Collisions. The conference was organized jointly by SINAP (Shanghai Institute of Applied Physics, Chinese Academy of Sciences (CAS)) and CCNU (Central China Normal University, Wuhan). Over 600 scientists from 32 countries in five continents attended the conference. This is the first time that China has hosted such a premier conference in the field of relativistic heavy-ion collisions, an important event for the Chinese high energy nuclear physics community. About one half of the conference participants are junior scientists—a clear indication of the vigor and momentum for this field, in search of the fundamental nature of the nuclear matter at extreme conditions.

Professor T D Lee, honorary chair of the conference and one of the founders of the quark matter research, delivered an opening address with his profound and philosophical remarks on the recent discovery of the nature of strongly-interacting quark-gluon-plasma (sQGP). Professor Hongjie Xu, director of SINAP, gave a welcome address to all participants on behalf of the two hosting institutions. Dr Peiwen Ji, deputy director of the Mathematics and Physics Division of the Natural Science Foundation of China (NSFC), also addressed the conference participants and congratulated them on the opening of the conference. Professor Mianheng Jiang, vice president of the Chinese Academy of Sciences (CAS), gave a concise introduction about the CAS as the premier research institution in China. He highlighted continued efforts at CAS to foster international collaborations between China and other nations. The Quark Matter 2006 conference is an example of such a successful collaboration between high energy nuclear physicists in China and other nations all over the world.

The scientific program of the conference began with an overview of high energy nuclear physics in China by Professor Wenqing Shen, vice president of the National Natural Science Foundation of China. Professor Shen highlighted many contributions made by the Chinese scientists in both theory and experiment. Dr Nick Samios, former director of Brookhaven National Laboratory (BNL), gave a vivid account of the early years of RHIC and recent accomplishments.

Highlights of the conference include new results from RHIC at BNL and SPS (Super Proton Synchrotron) at CERN (European Organization for Nuclear Research). Many experimental results reported at the conference support the notion that the quark-gluon matter at RHIC behaves like a perfect liquid with minimum viscosity to entropy ratio. There were 15 plenary sessions which covered 54 plenary talks, 12 parallel sessions and 1 poster session. A total of 320 abstracts were submitted to the conference out of which 124 were selected for oral presentation and the rest were assigned to the poster session. Talks and posters in the conference covered a broad range of experimental and theoretical progress in ultra-relativistic heavy-ion collisions, which includes new evidence of sQGP, jet quenching and heavy quark energy loss, heavy-ion collision phenomenology, quantum field theory at finite temperature and/or density, and relevant areas of astrophysics and plasma physics.

The Quark Matter 2006 conference coincided with the 80th birthday of Professor T D Lee. A special reception was held in the banquet hall of the Shanghai Grand Theatre to celebrate Professor Lee's birthday and to honor his great contributions to physics, in particular, to the development of high energy nuclear physics research in China.

We would like to thank the members of the International Advisory Committee for providing valuable advice on a variety of matters, from the general structure of the conference to the selection of the plenary speakers and selection of abstracts for oral presentations. Professors T Hemmick, H Satz, D T Son and N Xu gave excellent pedagogical lectures in the pre-conference student symposium and their efforts were greatly appreciated.

The Shanghai Association of Science and Technology (SAST) and the staff of the Shanghai science hall provided valuable assistance and services during the conference. The conference would not have run so smoothly without their professional dedication. We also thank Professor Wenqing Shen, Chairman of the SAST, for his many valuable suggestions to the conference organizers and for providing close cooperation with SAST staff.

We thank members of the Local Organizing Committee for many useful suggestions and help. We would like to express our special appreciation for the tireless efforts by many local staff who worked very hard to make this conference a success. Dr Xiang-Zhou Cai, Mrs Wei Zhou and Mrs Yang Shen undertook many duties to coordinate and organize the local services. Dr Kun Wang took responsibility of the conference web page. Dr Wei Guo, Dr Wendong Tian, Mr Chunwang Ma and Mrs Wanyan Qian organized student volunteers for the conference. Without their help and dedication this conference could not have been such a success.

The Quark Matter 2006 conference has received substantial financial support from many organizations, including the Chinese Academy of Sciences (CAS), the National Natural Science Foundation of China (NSFC), the Ministry of Education of China (MOE), Shanghai Science and Technology Committee (SSTC), Chinese Nuclear Physics Society (CNPS), Shanghai Institute of Applied Physics (SINAP), Central China Normal University (CCNU), China Center of Advanced Science and Technology (CCAST), Brookhaven National Laboratory (BNL), Lawrence Berkeley National Laboratory (LBNL), European Laboratory for Particle Physics (CERN), and Journal of Physics G: Nuclear and Particle Physics (IOP Publishing).

Organising Committee

Xiang-Zhou Cai (SINAP) Xu Cai (CCNU), Co-chair Zhan-Jun He (SINAP) TD Lee (Columbia University, CCAST), Honorary chair Ya-Hong Li Zuo-Tang Liang (Shandong University) Feng Liu (CCNU) Bo-Qiang Ma (Beijing University) Yu-Gang Ma (SINAP), Scientific secretary Ru-Keng Su (Fudan University) En-Ke Wang (CCNU), Scientific secretary Fan Wang (Nanjing University) Xiao-Lian Wang (USTC) Hu-Shan Xu (IMP) Wei-Qin Zhao (CCAST) Dai-Cui Zhou (CCNU) Shu-Hua Zhou (CIAE) Wei Zhou (SINAP) Zhi-Yuan Zhu (SINAP, CAS), Co-chair Peng-Fei Zhuang (Tsinghua University) Bing-Song Zou (IHEP)

International Advisory Committee

Jean Paul Blaizot, France Peter Braun Münzinger, Germany Igor M Dremin, Russia Christian Fabjan, Switzerland Jens Jorgen Gaardhoje, Denmark Hans-Ake Gustaffson, Sweden Hans Gutbrod, Germany Miklos Gyulassy, USA Timothy Hallman, USA Hideki Hamagaki, Japan John W Harris, USA Tetsuo Hatsuda, Japan Huan-Zhong Huang, USA Barbara Jacak, USA Peter Kevi, Hungary Thomas W Ludlam, USA Luciano Maiani, Italy Larry McLerran, USA Berndt Müller, USA Lodovico Riccati, Italy Hans Georg Ritter, USA Vesa Ruuskanen, Finland Jurgen Schukraft, Switzerland Wen-Qing Shen, China Edward V Shuryak, USA Bikash Sinha, India Johanna Stachel, Germany Horst Stöcker, Germany Itzhak Tserruya, Israel Xin-Nian Wang, USA Bolek Wyslouch, USA Fu-Jia Yang, China Glenn R Young, USA William A Zajc, USA Wen-Long Zhan, China Zong-Ye Zhang, China

In this talk, I first discuss the history of the Shanghai Association of Science and Technology (SAST) where the present Quark Matter conference was held. Secondly, I review the status of high-energy nuclear physics in China, including brief introductions to the institutions and the accelerator-based facilities. Special emphasis is given to international collaborations, such as RHIC–STAR and CERN-LHC collaborations.

The history of the realization of the RHIC accelerator complex is reviewed including, physics, machine, political, organizational and community issues.

In this contribution I present recent results from the PHENIX collaboration, with a particular emphasis on measurements relating to the propagation of partons in a coloured medium.

New physics results with identified particles at STAR are presented. Measurements at low p_T address bulk properties of the collision, while those at high p_T address jet energy loss in the bulk matter produced. Between these extremes, measurements at intermediate p_T address the interplay between jets and the bulk. We highlight: measurements of v₂ fluctuations as a new, sensitive probe of the initial conditions and the equation of state; correlations involving multi-strange particles, along with ratios of identified particles to test coalescence as a mechanism of particle production at intermediate p_T; three particle azimuthal correlation to search for conical emission; and the energy and particle-type dependence of hadron production at high p_T to study quark and gluon jet energy loss.

We present an overview of highlights from the BRAHMS Collaboration.

This paper contains a summary of the latest physics results from PHOBOS, as reported at Quark Matter 2006. Highlights include the first measurement from PHOBOS of dynamical elliptic flow fluctuations as well as an explanation of their possible origin, two-particle correlations, identified particle ratios, identified particle spectra and the latest results in global charged particle production.

We summarize here recent results from the STAR collaboration focusing on processes involving large momentum transfers. Measurements of angular correlations of di-hadrons are explored in both the pseudorapidity (η) and azimuthal (ϕ) projections. In central Au+Au, an elongated structure is found in the η projection which persists up to the highest measured p_⊥. After quantifying the particle yield in this structure and subtracting it from the near-side yield, we observe that the remainder exhibits a behaviour strikingly similar to that of the near-side yield in d+Au. For heavy flavour production, using electron–hadron correlations in p + p collisions, we obtain an estimate of the b-quark contribution to the non-photonic electrons in the p_⊥ region 3–6 GeV/c, and find it consistent with FONLL calculations. Together with the observed suppression of non-photonic electrons in Au+Au, this strongly suggests suppression of b-quark production in Au+Au collisions. We discuss results on the mid-rapidity ϒ cross-section in p + p collisions. Finally, we present a proof-of-principle measurement of photon–hadron (γ–h) correlations in p + p collisions, paving the way for the tomographic study of the matter produced in central Au+Au via γ-jet measurements.

NA60 has been the last heavy ion experiment running at the SPS. It has performed measurements on dimuon production with an indium beam at 158 AGeV/c and with a proton beam at 158 and 400 GeV/c, focusing on (i) the study of the ρ spectral function in nuclear collisions, (ii) the unambiguous determination of the open charm yield and the quantitative assessment of the production of thermal radiation in the intermediate mass region, and (iii) the study of the J/ψ suppression in a collision system other than Pb–Pb. This paper provides an overview of the latest results. In addition, several other SPS experiments are still producing physics results. Interesting highlights from WA98, NA45 and NA49 on (i) nuclear modification factors of neutral and charged pions, (ii) three particle correlations at high transverse momentum and (iii) net baryon distributions will be addressed at the end of the paper.

I give a brief overview of recent theoretical developments concerning the high temperature phase of QCD and the structure of hadronic wavefunctions at high energy.

Some of the means through which the possible presence of nearly deconfined quarks in neutron stars can be detected by astrophysical observations of neutron stars from their birth to old age are highlighted.

The interest in hot and baryon-dense matter has recently intensified because of the prospects for exploring this phase region by a downgraded RHIC and the future FAIR. The baryon excess, the spatial irregularity of the system and its rapid evolution, and particularly the presence of a phase transition, pose interesting theoretical challenges that must be addressed in the development of the transport models required for the planning and interpretation of the experiments.

I review various approaches to determining the transport properties of the quark gluon plasma from heavy ion data. First, I review efforts to extract the transport properties from small colliding systems such as CuCu. Then I discuss the application of viscous hydrodynamics to various parts of the heavy ion reaction. I emphasize the progress and the current difficulties in understanding the data with these methods.

The property of the 'perfect liquid' created at RHIC is probed with anisotropic flow measurements. Different initial conditions and their consequences on flow measurements are discussed. The collectivity is shown to be achieved fast and early. The thermalization is investigated with the ratio of v₄/v²₂. Measurements from three sectors of soft physics (HBT, flow and strangeness) are shown to have a simple, linear, length scaling. Directed flow is found to be independent of system size.

We review recent developments in lattice simulations of the equation of state, the order of the thermal phase transition and the determination of the pseudo-critical temperature in (2+1)-flavour QCD. Owing to the increasing computer power, new algorithms and improved fermion formulations, studies of bulk QCD matter approach the stage of precision science. We have also reviewed recent lattice results on the spectral properties of the heavy quarkoniums inside the quark–gluon plasma (QGP). Although they are still at an exploratory stage, interesting physics in relation with the strongly correlated QGP is being extracted.

Substantial collective flow is observed in collisions between large nuclei at high energy, as evidenced by single-particle transverse momentum distributions and by azimuthal correlations among the produced particles. The data are well reproduced by perfect fluid dynamics. In a separate development, calculation of the dimensionless ratio of shear viscosity η to entropy density s by Kovtun, Son and Starinets within AdS/CFT yields η/s = 1/4π, and they conjectured that this is a lower bound for any physical system. It is shown that the transition from hadrons to quarks and gluons has behaviour similar to helium, nitrogen and water at and near their phase transitions in the ratio η/s. Therefore, it is possible that experimental measurements can pinpoint the location of this transition or rapid crossover in QCD via the viscosity to entropy ratio in addition to and independently of the equation of state.

In a few years of RHIC running major advances have been made in understanding the dynamics of heavy-ion collisions in this new regime of unprecedented high-energy densities. Ultra-relativistic heavy-ion collisions at RHIC have provided a unique environment to create a nuclear medium that exhibits a variety of novel properties (Arsene et al 2005 Nucl. Phys. A 757 1, Back et al 2005 Nucl. Phys. A 757 28, Adcox et al 2005 Nucl. Phys. A 757 184, Adams et al 2005 Nucl. Phys. A 757 102). Determining whether the quarks and gluons in this matter reach thermal equilibrium with one another before they become confined within hadrons is one of the most important questions for understanding this new form of matter. A set of interesting features indicating relevance of partonic degrees of freedom at hadronization is observed in the identified measurements of nuclear modification factors, elliptical flow (v₂) and particle ratios in the intermediate transverse momentum range (2 < p_T < 6 GeV/c) at RHIC. Those observations are reviewed in this paper in the context of various theoretical models.

We give a short review of hydrodynamic models at heavy ion collisions from the point of view of initial conditions, an equation of states (EoS) and a freezeout process. Then we show our latest results of a combined fully three-dimensional macroscopic/microscopic transport approach. In this model for the early, dense, deconfined stage relativistic 3D hydrodynamics of the reaction and a microscopic non-equilibrium model for the later hadronic stage where the equilibrium assumptions are no longer valid are employed. Within this approach we study the dynamics of hot, bulk QCD matter, which is being created in ultra-relativistic heavy ion collisions at RHIC.

Due to the presence of a large orbital angular momentum of the parton system produced at the early stage of non-central heavy-ion collisions, quarks and anti-quarks are shown to be polarized in the direction opposite to the reaction plane which is determined by the impact parameter and the beam momentum. The global quark polarization via elastic scattering was first calculated in an effective static potential model, then using QCD at finite temperature with the hard-thermal-loop re-summed gluon propagator. The measurable consequences are discussed. Global hyperon polarization from the hadronization of polarized quarks is predicted independent of the hadronization scenarios. It has also been shown that the global polarization of quarks and anti-quarks also leads to spin alignment of vector mesons. Dedicated measurements at RHIC are underway and some of the preliminary results are obtained. Here the basic idea and main results of global quark polarization are presented. The direct consequences such as global hyperon polarization and spin alignment are summarized.

We report on STAR measurements of global polarization for vector mesons K*⁰(892) and ϕ(1020) at midrapidity from noncentral Au+Au collisions at . The measured diagonal spin density matrix elements for particles up to a transverse momentum 5 GeV/c are ρ₀₀ = 0.36 ± 0.02 (stat) ± 0.13 (sys) for K*⁰(892) and ρ₀₀ = 0.38 ± 0.01 (stat) ± 0.04 (sys) for ϕ(1020) with respect to the reaction plane, where 1/3 is the value for no polarization. With respect to the vector mesons' production planes, ρ₀₀ for K*⁰(892) and ϕ(1020) in Au+Au and for ϕ(1020) mesons in p+p collisions at is also presented. There is no significant difference for the measured spin alignment between Au+Au and p+p collisions with our data sample. We have also obtained an upper limit for global polarization.

Modifications of jet-like azimuthal correlations have revealed novel properties of the medium created in relativistic heavy-ion collisions. Experimental results on jet-like 2- and 3-particle correlations, specifically 'punch-through' at high transverse momentum, broadening at low and modest transverse momentum, and particularly the possible experimental evidence for conical flow, are reviewed. Future prospects of jet-like correlations and their physics potential are discussed.

The experimental azimuthal dihadron distributions at RHIC show a double peak structure in the away side (Δϕ = π ± 1.2 rad) for intermediate p_t particles. A variety of models have appeared trying to describe this modification. We will review most of them, with special emphasis on the conical flow scenario in which the observed shape is a consequence of the emission of sound by a supersonic high momentum particle propagating in the quark gluon plasma.

Over the last six years RHIC has collected a wealth of data for various systems and collision energies providing valuable information for understanding the properties of the medium produced in high-energy heavy ion collisions. A review of the high-p_T hadron spectra in p+p and A+A collisions is presented. The energy loss mechanisms are discussed. The sensitivity of the different hadron species to model parameters is examined.

We review some recent applications of the AdS/CFT correspondence to heavy ion collisions including a calculation of the jet quenching parameter in super-Yang–Mills theory and quarkonium suppression from velocity scaling of the screening length for a heavy quark–antiquark pair. We also briefly discuss differences and similarities between QCD and super-Yang–Mills theory.

The study of heavy-flavour production in relativistic heavy-ion collisions is an extreme experimental challenge but provides important information on the properties of the quark–gluon plasma (QGP) created in Au+Au collisions at RHIC. Heavy quarks are believed to be produced in the initial stages of the collision, and are essential for the understanding of parton energy loss in the dense medium created in such environment. Moreover, heavy quarks can help to investigate the fundamental properties of QCD in elementary p+p collisions. In this work, we review recent results on heavy-flavour production and their interaction with the hot and dense medium at RHIC.

The four major approximation schemes devised to study the modification of jets in dense matter are outlined. The comparisons are restricted to basic assumptions and approximations made in each case and the calculation methodology used. Emergent underlying similarities between apparently disparate methods brought about by the approximation schemes are exposed. Parameterizations of the medium in each scheme are discussed in terms of the transport coefficient . Discrepancies between the estimates obtained from the four schemes are discussed. Recent developments in the basic theory and phenomenology of energy loss are highlighted.

In the RHIC era, the use of direct photon physics to probe heavy ion collisions has developed beyond its original scope. I make evaluations of the current state of several measurements by RHIC experiments and their associated physics implications, with a focus on their current and desired precision. At low p_T, thermal photon theory is still not well constrained by the data, but improvements are on the way. At higher p_T, we have been able to gain important insights, now with regards to the proposed 'jet-medium' photon sources (Fries, Muller and Srivastava 2003 Phys. Rev. Lett.90 132301 (Preprint nucl-th/0208001); Zakharov 2004 JETP Lett.80 617). Such predictions, as they currently exist, seem to be disfavoured by the PHENIX data; however, the idea is probably not ruled out. Finally, direct γ-jet correlations have been measured for the first time at RHIC and already show hints of medium modification.

The current status of experimental searches for modifications of vector mesons in the nuclear medium is reviewed. Results on ρ, ω and Φ mesons are presented, obtained in elementary reactions with proton and photon beams as well as in heavy-ion collisions. At normal nuclear matter density, ω and Φ mesons are found to be lowered in mass by 9–14% and 3.5% and broadened by about factors 10 and 3.6, respectively, compared to the free particle properties. For the ρ meson, conflicting results on in-medium mass shifts and broadening have been reported by different experiments.

Electromagnetic probes promise to be direct messengers of (spectral properties of) hot and dense matter formed in heavy-ion collisions, even at soft momentum transfers essential for characterizing possible phase transitions. We examine how far we have progressed towards this goal by highlighting recent developments, and trying to establish connections between lattice QCD, effective hadronic models and phenomenology of dilepton production.

Transport models that take into account non-equilibrium partonic dynamics of relativistic heavy ion collisions are useful tools for relating the properties of the produced partonic matter to the experimental observables. In this talk, we review results obtained from some of the transport models, particularly the multiphase AMPT transport model, regarding the partonic effects on observables from relativistic heavy ion collisions. Also discussed are recent results from the AMPT model for the dependence of the ratio of parton hexadecupole flow to the square of its elliptic flow on the parton collision number and the separation distribution of pion pairs emitted from a heavy ion collision.

At large collision energy and relatively low momentum transfer Q, one expects a new regime of quantum chromo-dynamics (QCD) known as 'saturation'. This kinematical range is characterized by a very large occupation number for gluons inside hadrons and nuclei; this is the region where higher twist contributions are as large as the leading twist contributions incorporated in collinear factorization. In this talk, I discuss the onset of and dynamics in the saturation regime, some of its experimental signatures and its implications for the early stages of heavy ion collisions.

Despite the apparent success of ideal hydrodynamics in describing the elliptic flow data which have been produced at Brookhaven National Lab's Relativistic Heavy Ion Collider, one lingering question remains: is the use of ideal hydrodynamics at times t < 1 fm/c justified? In order to justify its use, a method for rapidly producing isotropic thermal matter at RHIC energies is required. One of the chief obstacles to rapid isotropization/thermalization is the rapid longitudinal expansion of the matter during the earliest times after the initial nuclear impact. As a result of this expansion, the parton distribution functions become locally anisotropic in momentum space. In contrast to locally isotropic plasmas, anisotropic plasmas have a spectrum of soft unstable modes which are characterized by an exponential growth of transverse chromo-magnetic/-electric fields at short times. This instability is the QCD analogue of the Weibel instability of QED. Parametrically, the chromo-Weibel instability provides the fastest method for generation of soft background fields and dominates the short-time dynamics of the system.

We discuss the phase structure and fluctuations of conserved charges in two-flavour QCD. The importance of the density fluctuations to probe the existence of the critical end point is summarized. The role of these fluctuations to identify the first-order phase transition in the presence of spinodal phase separation, is also discussed.

Two decades ago Matsui and Satz suggested that Debye screening in the quark–gluon plasma would result in J/ψ suppression in heavy ion collisions. Much has happened in the subsequent years, and the picture of quark–gluon plasma at present is rapidly evolving—what does it imply for the J/ψ suppression? What are the recent RHIC and SPS results trying to tell us? What else has to be done? This talk is an attempt to address these questions.

Quarkonia (J/ψ, ψ', ϒ) production provides a sensitive probe of gluon distributions and their modification in nuclei and is a leading probe of the hot-dense (deconfined) matter created in high-energy collisions of heavy ions. We will discuss the current understanding of the production process and of the cold-nuclear-matter effects that modify this production in nuclei in the context of recent p+p and p(d)+A quarkonia measurements. Then we will review the latest results for nucleus–nucleus collisions from RHIC, and together with the baseline results from d+A and p+p collisions, discuss several alternative explanations for the observed suppressions and future prospects for distinguishing these different pictures.

The NA60 experiment studies dimuon production in In–In and p–A collisions at the CERN SPS. We report recent results on J/ψ production, measured through its muon pair decay. As a function of centrality, we show that in In–In the J/ψ yield is suppressed beyond expectations from nuclear absorption. We present also for the first time results on J/ψ production in p–A collisions at 158 GeV, the same energy of the nucleus–nucleus data. For both p–A and In–In we show preliminary results on ψ' suppression. Finally, we have studied the kinematical distributions of the J/ψ produced in In–In collisions. We present results on transverse momentum and rapidity, as well as on the angular distribution of the J/ψ decay products.

After a brief review of the various scenarios for quarkonium production in ultra-relativistic nucleus–nucleus collisions, we focus on the ingredients and assumptions underlying the statistical hadronization model. We then confront model predictions for J/ψ phase space distributions with the most recent data from the RHIC accelerator. Analysis of the rapidity dependence of the J/ψ nuclear modification factor yields first evidence for the production of J/ψ mesons at the phase boundary. We conclude with predictions for charmonium production at the LHC.

We review the present status of theoretical predictions for both closed (J/ψ) and open heavy quark production in high energy collisions, and their comparisons to experimental data.

We investigate the competition between J/ψ suppression and regeneration in heavy ion collisions at RHIC energy. The J/ψ transport equation, with both gain and loss terms that are controlled by the pQCD processes , together with the hydrodynamic evolution is solved in a self-consistent manner. Nuclear modification factor R_AA and elliptic flow v₂ are presented and compared with the RHIC data.

The photoproduction of vector mesons on various nuclei has been studied using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Laboratory. All three vector mesons ρ, ω and ϕ are observed via their decay to e⁺e⁻. The possible in-medium effects on the properties of the ρ meson are of particular interest. The ρ spectral function is extracted from the data on carbon, iron and titanium, and compared to the spectrum from liquid deuterium, which is relatively free of nuclear effects. We observe no effects on the mass of the ρ meson, some widening in titanium and iron is observed consistent with the collisional broadening.

This talk discusses extrapolations to the LHC of several, apparently universal trends, seen in the data on relativistic nucleus–nucleus collisions up to RHIC energies. In the soft physics sector, such extrapolations to the LHC are typically at odds with LHC predictions of the dynamical models, advocated to underlie multi-particle production up to RHIC energies. I argue that due to this, LHC is likely to be a discovery machine not only in the hard, but also in the soft physics sector.

The ALICE detector, expected to start operating at the Large Hadron Collider this year, was designed specifically for the study of heavy-ion collisions. In this paper, we recall the main features of the apparatus and give some examples of the expected physics performance.

The Large Hadron Collider (LHC) at CERN will collide protons at and lead ions at . The research program of the Compact Muon Solenoid (CMS) experiment includes a strong heavy-ion physics agenda, especially in the measurement of hard processes. The high centre-of-mass energies available at the LHC will allow high statistics studies of high-density QCD with hard probes: heavy quarks and quarkonia with an emphasis on the J/ψ and ϒ, high-p_T jets, direct photons as well as Z⁰ bosons. In addition to the detailed studies of hard probes, CMS will measure charged particle multiplicity and energy flow with respect to the reaction plane on an event-by-event basis. Studies of the CMS capabilities and physics reach for different high-density QCD observables, using the full detector simulation and reconstruction, are presented.

The ATLAS detector at CERN will provide a high-resolution longitudinally segmented calorimeter and precision tracking for the upcoming study of heavy ion collisions at the LHC ( GeV). The calorimeter covers |η| < 5 with both electromagnetic and hadronic sections, while the inner detector spectrometer covers |η| < 2.5. ATLAS will study a full range of observables necessary to characterize the hot and dense matter formed at the LHC. Global measurements (particle multiplicities, collective flow) will provide access into its thermodynamic and hydrodynamic properties. Measuring complete jets out to 100's of GeV will allow detailed studies of energy loss and its effect on jets. Quarkonia will provide a handle on deconfinement mechanisms. ATLAS will also study the structure of the nucleon and nucleus using forward physics probes and ultraperipheral collisions, both enabled by segmented zero degree calorimeters.

Strategies for identifying speculative mini black hole events (due to large extra dimensions) at future colliders are reviewed. Estimates for production cross sections, Hawking radiation, di-jet suppression and multi- mono-jet emission are surveyed. We further report on a class of effective entropy formulae that could lead to the formation of a final black hole remnant state, BHR. Such BHRs could be both electrically charged and uncharged. Charged BHRs should be observable by single stiff charged tracks in the detectors. Collinear hadronic jets with a large missing transverse momentum are presented as new observable signal for electrically neutral black holes.

The planned collider upgrade and ongoing detector upgrades at RHICH will allow new access and statistical reach to physical observables in heavy ion collisions. We discuss the importance of these improved capabilities on the advancement of heavy ion physics. The RHIC II upgrade will provide a ten-fold luminosity improvement. The upgrades will allow more extensive beam species and energy scan studies. Calculations of the expected annual yields associated with measurements of heavy quark and jet production are presented. These calculations demonstrate a promising future in heavy quarkonia, high-pt direct photon, and jet studies at RHIC. Also shown is that through a combination of higher luminosities, longer running times, and lower backgrounds, RHIC II will be competitive with the LHC in many heavy ion measurements of interest.

A brief overview is presented of the future FAIR facility and its research programs, with emphasis on the strong-interaction and QCD-matter experiments.

An overview of new experimental results on high- particle production and jets in heavy ion collisions from the Quark Matter 2006 conference is presented.

The study of heavy-flavour production and electromagnetic probes in nuclear collisions provides unique access to the properties of strongly interacting matter at extreme energy densities. Highlights of experimental results presented at the Quark Matter 2006 conference are reviewed and open issues are discussed.

The experimental results which have been shown in Quark Matter 2006 are summarized and discussed especially focusing on the bulk properties and collective phenomena.

I report on the theoretical developments discussed in Quark Matter 2006.

In these proceedings we present STAR measurements of two-particle azimuthal correlations between trigger particles at mid-rapidity (|η| < 1) and associated particles at forward-rapidities (2.7 <|η|< 3.9) in p+p, d+Au and Au+Au collisions at . Two-particle azimuthal correlations between a mid-rapidity trigger particle and forward-rapidity-associated particles preferably probe large-x quarks scattered off small-x gluons in RHIC collisions. Comparison of the separate d- and Au-side measurements in d+Au collisions may potentially probe gluon saturation and the presence of colour glass condensate. In Au+Au collisions quark energy loss can be probed at large rapidities, which may be different from gluon energy loss measured at mid-rapidity.

We study high-energy proton–nucleus collisions within the colour glass condensate framework, and compute the probabilities of having a definite number of scatterings in the nucleus with a momentum transfer larger than a given cut. Various properties of the distribution in the number of multiple scatterings are investigated, and we conclude that events in which a monojet is equilibrated by many soft recoiling particles at a close rapidity are very unlikely, except for extreme values of the saturation scale Q_s.

Data from Au–Au, Cu–Cu and p–p collisions at GeV have been collected by the BRAHMS experiment from pseudorapidity η = 0–3.1. Nuclear modification factors, R_AA at forward rapidity, with p_T up to ∼2 GeV/c, which corresponds to more than half of the kinematical limit, are presented together with results from midrapidity for Au–Au and Cu–Cu collisions. They will also be shown as a function of centrality.

We introduce a generalized definition of parton distribution functions (PDFs) for a more consistent all-order treatment of power corrections. We present a new set of modified DGLAP evolution equations for nuclear PDFs, and show that the resummed α_sA^1/3/Q²-type of leading nuclear size enhanced power corrections significantly slow down the growth of gluon density at small-x, and drive the slope of parton evolution to zero, a necessary condition for parton saturation.

Measurements of x_F-dependent nuclear modification factors of charged mesons and protons in Au+Au collisions at and 62.4 GeV at RHIC are presented. Particle suppression at high-x_F is discussed in the context of kinematic constraints of particle production competing with dynamically induced nuclear modification mechanisms.

We discuss the relation between multi-particle production in the Glasma at next-to-leading order and the physics of plasma instabilities.

The BRAHMS experiment at RHIC has measured the transverse momentum spectra of charged pions, kaons and (anti-)protons over a wide range of rapidity in d+Au and p+p collisions at GeV. The nuclear modification factor R_dAu at forward rapidity shows a clear suppression for π⁺. The measured net-proton yields in p+p collisions are compared to PYTHIA and HIJING/B and seem to be better described by the latter.

We calculate some corrections to the JIMWLK kernel in the framework of the light-cone wavefunction approach to the high-energy limit of QCD. The contributions that we consider originate from higher order corrections in the strong coupling and in the density of the projectile to the solution of the classical Yang–Mills equations of motion that determine the Weizsäcker–Williams fields of the projectile. We study the structure of these corrections in the dipole limit, showing that they are subleading in the limit of large number of colours N and that they cannot be fully recast in the form of dipole degrees of freedom.

We present results from a calculation of the transition temperature in QCD with two light (up, down) and one heavier (strange) quark mass as well as for QCD with three degenerate quark masses. Furthermore, we discuss first results from an ongoing calculation of the QCD equation of state with almost realistic light and strange quark masses.

Several distinct perturbative approaches exist to describe the equation of state of QCD in the deconfined phase: dimensional reduction works for temperatures larger than the screening mass, otherwise one has to apply HDL/HTL resummation schemes at small temperatures or resort to the result by Freedman and McLerran at zero temperature. We present a new method that unifies these approaches in a manifestly four-dimensional calculation. We work out our new method for the pressure up to and including order g⁴ and verify that it agrees to the previous approaches in their respective ranges of validity.

We investigate the interplay between the chiral and diquark condensates on the basis of the Ginzburg–Landau potential with QCD symmetry. We demonstrate that the axial anomaly drives a new critical point at low temperature in the QCD phase diagram and leads to a smooth crossover between the hadronic and colour superconducting phases.

We analyse the large-distance behaviour of static quark–anti-quark pair correlations in QCD. The singlet free energy is calculated and the entropy contribution to it is identified allowing us to calculate the excess internal energy. The free energy has a sharp drop in the critical region, leading to sharp peaks in both excess entropy and internal energy.

The recent progresses in the theoretical study of bulk viscosity in nuclear and quark matter are reviewed. The constraints from baryon number conservation and electric neutrality in quark matter on particle densities and fluid velocity divergences are discussed.

The PNJL model is used to study the thermodynamics of N_f = 2 quark flavours interacting through chiral four-point couplings and propagating in a homogeneous Polyakov loop background. The input is fixed exclusively by selected pure-gauge lattice QCD results and by pion properties in vacuum. We present successful comparisons with lattice QCD thermodynamics expanded to finite chemical potential μ_q. Quark number susceptibilities at finite quark chemical potential are investigated. The validity of the Taylor expansion is then examined through a comparison between the full and truncated PNJL model calculations.

We report the current status of our systematic studies of the QCD thermodynamics by lattice QCD simulations with two flavours of improved Wilson quarks. We evaluate the critical temperature of two-flavour QCD in the chiral limit at a zero chemical potential and show the preliminary result. Also we discuss fluctuations at non-zero temperature and density by calculating the quark number and isospin susceptibilities and their derivatives with respect to the chemical potential.

We study the phase diagram of quark matter at finite temperature (T) and chemical potential (μ) in the strong coupling region of lattice QCD for colour SU(3). Baryon has effects to extend the hadron phase to a larger μ direction relative to T_c at low temperatures in the strong coupling limit. With the 1/g² corrections, T_c is found to decrease rapidly as g decreases, and the shape of the phase diagram becomes closer to that expected in the real world.

Superfluidity, or superconductivity with mismatched Fermi momenta, appears in many systems such as charge-neutral dense quark matter, asymmetric nuclear matter, and in imbalanced cold atomic gases. The mismatch plays the role of breaking the Cooper pairing, and the pair-breaking state cannot be properly described in the framework of standard BCS theory. I give a brief review on recent theoretical developments in understanding unconventional colour superconductivity, including a gapless colour superconductor, chromomagnetic instabilities and the Higgs instability in the gapless phase. I also introduce a possible new framework for describing an unconventional colour superconductor.

Hard processes are a well-calibrated probe to study heavy-ion collisions. However, the information to be gained from the nuclear suppression factor R_AA is limited, hence one has to study more differential observables to do medium tomography. The angular correlations of hadrons associated with a hard trigger appear suitable as they show a rich pattern when going from low p_T to high p_T. Of prime interest is the fate of away-side partons with an in-medium pathlength O (several fm). At high p_T, the correlations become dominated by the punchtrough of the away-side parton with subsequent fragmentation. We discuss what information about the medium density can be gained from the data.

We present preliminary STAR results on three-particle azimuthal angle correlation studies in Au+Au collisions at GeV. The studies are carried out at mid-rapidity between a trigger particle with 3 ⩽p_⊥⩽ 4 GeV/c and two associated particles in 1 ⩽p_⊥⩽ 2 GeV/c. A cumulant analysis reveals finite three-particle azimuthal correlations, dominated by near- and away-side particle correlations consistent with jet production, and jet-flow correlations. We use a two-component model to remove underlying background correlations. This analysis indicates the presence of the conical emission signals in central Au+Au collisions within the model assumptions about background composition and normalization.

We report the analysis of high-p_T hadron angular correlation performed by the PHENIX collaboration. The goal of the analysis is to investigate the medium modification of jets in the RHIC heavy-ion collisions. Two angular correlation techniques are used in our analysis: two-particle azimuthal correlation (2-p) and three-particle correlation (3-p). In the 2-p analysis, we focus on the p_T and collision system evolution of the jets medium modification. In the 3-p analysis, we focus on the discrimination of two scenarios of jets medium modification, Mach Cone (Casalderrey-Solana J et al 2006 Preprint hep-ph/0602183) and deflected jets (Hwa Chiu 2006 Preprint nucl-th/0609038).

One of the most striking observations made at RHIC in the last few years is the atypical non-Gaussian shape of the away-side azimuthal correlation of high-p_⊥ particles. We show that, without invoking new mechanisms, these non-Gaussian shapes find a natural explanation within the usual approach to jet quenching, namely the radiative energy loss.

Systematic measurements of pseudorapidity (Δη) and azimuthal (Δϕ) correlations between high-p_t charged hadrons in = 200 GeV Au+Au collisions are presented. An enhancement of correlated yield at large Δη on the near side is observed. This effect persists up to trigger p^trig_t∼ 9 GeV/c, indicating that it is associated with jet production. A more detailed analysis suggests distinct short-range and long-range components in the correlation.

Two-particle azimuthal correlations have been shown to be a powerful probe for extracting novel features of the interaction between hard scattered partons and the medium produced in Au+Au collisions at RHIC. At intermediate p_T, 2–5 GeV/c, jets have been shown to be significantly modified in both particle composition and angular distribution compared to p+p collisions. We present recent PHENIX results from Au+Au collisions for a variety of p_T and particle combinations.

We study the effects of jet quenching on the hydrodynamical evolution of the quark–gluon plasma (QGP) fluid created in a heavy-ion collision. Assuming that the deposited energy quickly thermalizes, we simulate the subsequent hydrodynamic evolution of the QGP fluid. For partons moving at supersonic speed and sufficiently large energy loss, jet quenching can lead to conical flow.

Two- and three-particle azimuthal correlations have been investigated in central Au + Au collisions at = 200 GeV with a partonic transport model. A hump structure on the away side, so-called 'Mach-like structure', which was observed in two- (three-) particle correlations in RHIC experiments, has been reproduced by the partonic transport model. It indicates that a strong parton cascade can couple partons together to show an apparent collective behaviour, i.e. a partonic Mach-like shock wave, due to a big partonic interaction cross section.

Azimuthal correlations of hadrons with high transverse momenta serve as a measure to study the energy loss and the fragmentation pattern of jets emerging from hard parton–parton interactions in heavy-ion collisions. Preliminary results from the CERES experiment on two- and three-particle correlations in central Pb–Au collisions are presented. A strongly non-Gaussian shape on the away-side of the two-particle correlation function is observed, indicating significant interactions of the emerging partons with the medium. Mechanisms like deflection of the initial partons or the evolution of a mach cone in the medium can lead to similar modifications of the jet structure on the away-side. An analysis based on three-particle correlations is presented which helps us to shed light on the origin of the observed away-side pattern.

A new hadron blind detector (HBD) for electron identification in high density hadron environment has been installed in the PHENIX experiment at RHIC in the fall of 2006. The HBD will identify low momentum electron–positron pairs to reduce the combinatorial background in the e⁺e⁻ mass spectrum, mainly in the region below 1 GeV/c². The HBD is a windowless proximity-focusing Cherenkov detector with a radiator length of 50 cm, a CsI photocathode and three layers of gas electron multipliers (GEM). Pure CF₄ is used as a radiator and a detector gas. This proceeding describes the construction details and the expected performance of the HBD.

The main tracking detector of the ALICE experiment at the LHC is a large time projection chamber. This detector has been fully assembled and, before being lowered to the underground experimental area, was commissioned with cosmic rays and tracks produced by an UV laser system. This paper presents the commissioning including preliminary results from the analysis of data on noise, electron diffusion, drift velocity and spatial resolution.

The capabilities of the CMS experiment to study the low-x parton structure and QCD evolution in the proton and the nucleus at LHC energies are presented through four different measurements, to be carried out in Pb–Pb at = 5.5 TeV: (i) the charged hadron rapidity density dN_ch/dη and (ii) the ultraperipheral (photo)production of ; and in p–p at = 14 TeV: (iii) inclusive forward jets and (iv) Müller–Navelet dijets (separated by Δη≳ 8).

In order to understand the partonic EOS of matter created at RHIC, one needs to study both the collectivity of the produced matter and the degree of thermalization. We propose to address this physics through the study of heavy flavour hadrons in high-energy nuclear collisions at RHIC. The heavy flavour tracker (HFT), a tracking upgrade of the STAR experiment, is being designed to provide an unambiguous measurement of charm hadrons through the direct reconstruction of hadronic decays. These measurements require high accuracy space points near the collision vertex. The current design of our detector uses a novel CMOS-based sensor, allowing for a low-mass and high-resolution detector element. We provide rate estimations for D⁰ v₂ measurements in Au+Au collisions at 200 GeV.

We discuss the physics requirements of the ALICE PHOton Spectrometer (PHOS) and describe its main characteristics and structure. The beam test results of the PHOS show that PHOS is capable of detecting photons efficiently up to 100 GeV/c in ALICE.

This paper describes the most important features of the ALICE Time-of-Flight (TOF) detector. The steps performed in the detector assembling are presented and the status of the detector mounting is discussed.

With the successful runs of the multi-gap resistive plate chamber (MRPC)-based time-of-flight (TOF) prototypes in the solenoid tracker at RHIC (relativistic heavy ion collider) (STAR) for the past several years, a full barrel TOF is being built to take part in data taking in late 2008. Together with other sub-detectors in STAR this TOF will greatly enhance the reach of the STAR scientific programme significantly by extending the particle identification (PID) capability. It will allow STAR to extract the maximum amount of information available from soft physics measures on an event-by-event basis. It will also extend its power to the heavy flavour sector by increasing the signal-to-noise ratios for charm hadron reconstructions for D⁰, D⁺, D⁺_s, J/ψ, enabling STAR to make systematic studies of charm thermalization and charm meson flow. The physics results achieved by the TOF prototypes as well as the goal of the full TOF expectable are presented.

We present a study of the CMS trigger system in heavy-ion collisions. Concentrating on two physics channels, dimuons from decays of quarkonia and single jets, we evaluate a possible trigger strategy for Pb + Pb running that relies on event selection solely in the high-level trigger (HLT). The study is based on measurements of the timing performance of the offline algorithms and event-size distributions using full simulations. Using a trigger simulation chain, we compare the physics reach for the jet and dimuon channels using online selection in the HLT to minimum bias running. The results demonstrate the crucial role the HLT will play for CMS heavy-ion physics.

The PHENIX experiment at RHIC has measured J/ψ production in and Cu+Cu collisions at forward (1.2 < |y| < 2.2) and mid (|y| < 0.35) rapidities. The most recent results for the rapidity and transverse momentum dependence of J/ψ production are presented and compared with PHENIX baseline p + p measurements and selected theoretical calculations. We find that the J/ψ production is significantly more suppressed, as compared to p + p, at forward rapidity than at mid rapidity in central Au+Au collisions.

Charm production from the direct reconstruction of D⁰ (D⁰ → Kπp_T up to 2 GeV/c) and indirect lepton measurements via charm semileptonic decays (c → e + X at 0.9 < p_T < 5.0 GeV/c and c → μ + X at 0.17 < p_T < 0.25 GeV/c) at collisions are analysed. The transverse momentum (p_T) spectra and the nuclear modification factors for D⁰ and for leptons from heavy flavour decays are presented. The scaling of charm cross-section with a number of binary collisions at from d+Au to Au+Au collisions is reported.

In this paper I discuss the pseudoscalar charmonium spectral function and correlator as obtained using a screened potential.

J/ψ production has been measured in Au+Au and Cu+Cu collisions at by the PHENIX experiment at the relativistic heavy ion collider (RHIC) during 2004 and 2005, respectively, at mid-rapidity (|η|⩽ 0.35) via J/ψ → e⁺e⁻ decay and at forward rapidity (1.2 ⩽|η|⩽ 2.2) via J/ψ → μ⁺μ⁻ decay. The nuclear modification factor (R_AA) of J/ψ is presented as a function of the collision centrality for Au+Au collisions (final results) and Cu+Cu collisions (preliminary results) in both rapidity windows. These results are compared to SPS results at lower energy and to various theoretical calculations.

The RHIC-PHENIX experiment has measured the azimuthal anisotropy parameter v₂, the second harmonic of the azimuthal distribution, for electrons at mid-rapidity (|η| < 0.35) as a function of transverse momentum (0.5 <p_T< 5.0 GeV/c) in Au+Au collisions at = 200 GeV. From the result, we have calculated heavy flavour (charm and bottom) electron v₂ by subtracting v₂ of electrons from other sources such as photon conversions and Dalitz decays. At the PHENIX experiment, the nuclear modification factor (R_AA) for the heavy flavour electrons is also measured. The property of the medium-created Au+Au collisions at = 200 GeV can be provided to these measurements.

We present an overview of cold nuclear matter effects on charmonium production at SPS and RHIC energies, including nuclear effects on the parton distribution functions and final-state nuclear absorption. A good understanding of these effects, present in proton–nucleus (p + A) and d+Au data, is crucial to establish a robust reference baseline with respect to which the nucleus–nucleus (A + A) data can be compared when searching for modifications signalling new physics.

Transverse momentum (p^e_T) distribution of electrons for 0.3 < p^e_T < 9.0 GeV/c has been measured in midrapidity (|η| < 0.35) in Au+Au collisions and p+p collisions at GeV by the RHIC-PHENIX experiment. Two methods for background subtraction were applied to determine the electron yield from open charm and bottom decays. The nuclear modification factor was calculated, and significant suppression at high-p^e_T was observed in Au+Au collisions, indicating the substantial energy loss of heavy quarks in a dense medium.

We revisit the question of the measured, unexpectedly large, heavy flavour suppression, R_AA(p_T) ≪ 1, in nucleus–nucleus collisions at RHIC and compare two new theoretical approaches to the D- and B-meson quenching. In the first model, radiative energy loss, collisional energy loss and heavy quark–resonance interactions are combined to evaluate the drag and diffusion coefficients in the quark–gluon plasma and the mixed phase. These are applied in a relativistic Fokker–Planck equation to simulate the heavy c- and b-quark suppression rate and elliptic flow v₂(p_T). In the second model, the fragmentation probability for heavy quarks and the medium-induced decay probability for heavy hadrons are derived. These are implemented in a set of coupled rate equations that describe the attenuation of the observable spectra from the collisional dissociation of heavy mesons in the QGP. An improved description of the non-photonic electron R_AA(p_T) at RHIC can be obtained. In contrast to previous results, the latter approach predicts suppression of B-mesons comparable to that of D-mesons at transverse momenta as low as p_T ∼ 10 GeV.

Heavy quark drag coefficients due to three-body elastic scattering in a quark–gluon plasma have been evaluated in the lowest order in QCD. They are found to have similar values as those due to two-body elastic scattering, and both are larger than those due to two-body radiative scattering if the momenta of charm and bottom quarks are below about 4 and 9 GeV/c, respectively. Including three-body elastic scattering increases the momentum degradation of heavy quarks in QGP, bringing the nuclear modification factor for electrons from the decays of produced heavy mesons in Au+Au collisions at closer to the measured one.

Quarkonia provide a sensitive probe of the properties of the hot dense medium created in high-energy heavy-ion collisions. Hard scattering processes result in the production of heavy quark pairs that interact with the collision medium during hadronization. These in-medium interactions convey information about the fundamental properties of the medium itself and can be used to examine the modification of the QCD confining potential in the collision environment. Baseline measurements from p+p and d+Au collision systems are used to distinguish cold nuclear matter effects while measurements from heavy-ion collision systems are used to quantify in-medium effects. The PHENIX experiment has the capability of detecting heavy quarkonia at 1.2 < |η| < 2.2 via the μ⁺μ⁻ decay channel and at |η| < 0.35 via the e⁺e⁻ decay channel. Recent runs have resulted in the collection of a high statistics p+p data set that provides an essential baseline reference for heavy-ion measurements and allow for further critical evaluation of heavy quarkonia production mechanisms. The latest PHENIX results for the production of the J/ψ mesons in p+p collisions are presented.

The ALICE experiment has several unique features which makes it an important contributor to proton–proton physics at the large hadron collider, in addition to its specific design goal of studying the physics of strongly interacting matter in heavy-ion collisions. The unique capabilities include its low transverse momentum (p_t) acceptance, excellent vertexing, particle identification over a broad p_t range and jet reconstruction. In this paper, a brief review of ALICE capabilities is given for studying bulk properties of produced particles which characterize the underlying events, and the physics of heavy-flavour, quarkonia, photons, di-leptons and jets.

Recent data on particles associated with Ω trigger suggest that such events have jet structure. However, the exponential p_T distribution of Ω suggests that no jets are involved. We resolve this puzzle by suggesting that the Ω is produced by the recombination of the enhanced thermal partons in the ridge that can have other hadrons in association with the trigger, all having exponential p_T distributions.

We present the incident energy and system size dependence of the p_T spectra for π^±, p and using Au+Au and Cu+Cu collisions at and 200 GeV in the STAR experiment at RHIC. Through these measurements in the p_T range of 0.2 < p_T < 10 GeV/c we conduct a systematic study of the beam energy, system size and particle species dependence of nuclear modification factors and address specific predictions from the quark coalescence models regarding the beam energy dependence of baryon enhancement in the intermediate p_T (2 <p_T< 6 GeV/c) region.

Transverse momentum spectra of neutral pions in the range 0.7 < p_T < 3.2 GeV/c have been measured at 2.3 ≲ η_lab ≲ 3.0 by the WA98 experiment in p+C and p+Pb collisions at . Scaled by the number of nucleon–nucleon collisions (N_coll), the π⁰ yields in p+C and p+Pb at p_T ≈ 2.0 − 2.5 GeV/c are higher than the respective yields in central Pb+Pb collisions with N_part ≳ 300. This observation is qualitatively consistent with expectations from parton energy loss.

The dihadron spectra in high energy AA collisions are studied within the NLO pQCD parton model with jet quenching taken into account. The high p_T dihadron spectra are found to be contributed not only by jet pairs close and tangential to the surface of the dense matter, but also by punching-through jets survived at the centre while the single hadron high p_T spectra are only dominated by 'surface emission'. Consequently, the suppression factor of such high-p_T hadron pairs is found to be more sensitive to the initial gluon density than the single hadron suppression factor.

Direct photon and neutral pion production with respect to the reaction plane at high-p_T were measured with the PHENIX experiment in Au+Au collisions at at mid-rapidity. The azimuthal asymmetry parameter v₂ for direct photons was found to be consistent with zero for all centrality classes. We evaluate the dependence of π⁰ suppression at high-p_T on the emission angle Δϕ with respect to the event reaction plane for seven centrality bins. For the peripheral bins we observe no suppression for neutral pions aligned with the reaction plane while π⁰'s produced perpendicular to the reaction plane are suppressed by factor 2. We found that a simple geometric picture can explain the observed suppression pattern.

With generalized factorization of twist-4 processes, we calculate quark–quark double scattering in eA DIS scattering. It is shown that quark–quark double scattering gives different modifications to quark and anti-quark fragmentation functions. We demonstrate that this difference may account for the significant differences between the multiplicity ratios for positive and negative hadrons as observed by HERMES.

High-p_T hadron–hadron correlations have been measured with the PHENIX experiment in and collisions at GeV. A comparison of the jet widths and yields between the two colliding systems allows us to study the medium effect on jets. We also present a first measurement of direct photon–hadron correlations in and collisions. We find that the near-side yields are consistent with zero in both systems. By comparing the jet yields on the away side, we observe a suggestion of the expected suppression of hadrons associated with photons in collisions.

We study the energy loss of an energetic heavy quark produced in a high temperature quark–gluon plasma and travelling a finite distance before emerging in the vacuum. While the retardation time of purely collisional energy loss is found to be of the order of the Debye screening length, we find that the contributions from transition radiation and the Ter–Mikayelian effect do not compensate, leading to an energy loss, the reduction of the zeroth-order (in an opacity expansion) energy loss.

We present the first measurement for the B meson semi-leptonic decay contribution to non-photonic electrons at RHIC using non-photonic electron azimuthal correlations with charged hadrons in p+p collisions at GeV from STAR.

We estimate the electromagnetic effect of the spectator charge on the momentum spectra of charged pions produced in peripheral Pb+Pb collisions at SPS energies. We find a large effect which results in strongly varying structures in the x_F dependence of the π⁺/π⁻ ratio, especially at low transverse momenta where a deep valley in the above ratio is predicted at x_F∼ 0.15–0.20. The effect depends on initial conditions. Thus, it provides new information on the space and time evolution of the non-perturbative pion creation process.

The coherent hadron production analogous to Cherenkov radiation of photons gives rise to the ring-like events. Being projected on the ring diameter they produce the two-bump structure recently observed for the away-side jets at RHIC. The position of the peaks and their height determine such properties of the hadronic medium as its nuclear index of refraction, the parton density, the free-path length and the energy loss of Cherenkov gluons. Beside comparatively low-energy gluons observed at RHIC, there could be high-energy gluons at LHC, related to the high-energy region of a positive real part of the forward scattering amplitude and possessing different characteristics.

Measurements of transverse momentum fluctuations can be used to determine the shear viscosity. We use current data to estimate the viscosity-to-entropy ratio in the range from 0.08 to 0.3, and discuss how future measurements can reduce this uncertainty.

We argue that an expanding quark–gluon plasma has an anomalous viscosity, which arises from interactions with dynamically generated colour fields. The anomalous viscosity dominates over the collisional viscosity for large velocity gradients or weak coupling. This effect may provide an explanation for the apparent near-perfect liquidity of the matter produced in nuclear collisions at RHIC without the assumption that it is a strongly coupled state.

Motivated by the recent lattice data that J/ψ will survive up to 1.6T_c, we calculate the thermal width of J/ψ at finite temperature in perturbative QCD. The inputs of the calculation are the parton quarkonium dissociation cross sections at the NLO in QCD, which were previously obtained by Song and Lee, and a Gaussian charmonium wavefunction, whose size was fitted to an estimate by Wong by solving the Schrödinger equation for charmonium in a potential extracted from the lattice at finite temperature. We find that the total thermal width above 1.4T_c becomes larger than 100 to 200 MeV, depending on the effective thermal masses of the quark and gluon, which we take it to vary from 600 to 400 MeV.

We study the evolution of a chemically equilibrating quark–gluon plasma in a (3+1)-dimensional spacetime at finite baryon density and its photon production. We find that the photon production is a strongly decreasing function of the ratio of quark chemical potential to temperature.

We solve the Yang–Mills equations in the framework of the McLerran–Venugopalan model for small times τ after a collision of two nuclei. An analytic expansion around τ = 0 leads to explicit results for the field strength and the energy–momentum tensor of the gluon field at early times. We then discuss constraints for the energy density, pressure and flow of the plasma phase that emerges after thermalization of the gluon field.

We investigate thermalization of gluons and energy loss of high p_T jets in the course of spacetime evolution of partons, simulated in a (3+1)-dimensional pQCD inspired on-shell parton cascade.

Thermalization of quark–gluon matter is studied with a transport equation that includes contributions of 2-to-2 and 3-to-3 elastic scatterings. Thermalization time is related to the squared amplitudes for the elastic scatterings that are calculated in perturbative QCD.

The direct photon spectrum measured by the PHENIX collaboration in Au + Au collisions at has been analysed. It has been shown that the data can be reproduced reasonably well by assuming a deconfined state of thermalized quarks and gluons. The effects of the equation of state on the value of the initial temperature have been studied. The modifications of hadronic properties at non-zero temperature have been taken into account.

Direct photon spectra measured at small p_T in p+p, d+Au and Au+Au collisions at are presented. Several measurement techniques including statistical subtraction, tagging, and internal and external conversion were applied and found to produce consistent results. The p+p and d+Au results are found to be in very good agreement with pQCD predictions over the entire p_T range. The direct photon yield in Au+Au collisions is compared to binary scaled d+Au data but the large systematic errors in d+Au results do not allow us to draw conclusions on the presence of a direct photon excess due to matter-related emission in Au+Au collisions.

A parton and hadron cascade model, PACIAE, is used in investigating the PHENIX data of the direct photon and π⁰ invariant differential cross sections in p + p collisions and the direct photon and π⁰p_T distributions in 0–10% of most central Au + Au collisions at top RHIC energy. It turns out that the above data are possible to be described by this microscopic transport model.

We investigate the robustness of the discovery of the perfect fluid through comparison of hydrodynamic calculations with the elliptic flow coefficient v₂ at midrapidity in Au+Au collisions at . Employing the Glauber model for initial entropy density distributions, the centrality dependence of v₂ is reasonably reproduced by using an ideal fluid description of the early QGP stage followed by a hadronic cascade in the late hadronic stage. On the other hand, initial conditions based on the colour glass condensate model are found to generate larger elliptic flow due to larger initial eccentricity ε. We further predict v₂/ε at a fixed impact parameter as a function of collision energy up to the LHC energy.

We report measurements of charged particle elliptic flow at mid-rapidity in Au+Au and Cu+Cu collisions at and 200 GeV. Using correlations between main STAR TPC and forward TPCs ensures minimal bias due to non-flow effects. We further investigate the effect of flow fluctuations on v₂/ε scaling studying initial geometry eccentricity fluctuations in the Monte Carlo Glauber model. It is found that accounting for the effect of flow fluctuations improves v₂/ε scaling.

We present a systematic study of elliptic flow as a function of centrality, pseudorapidity, transverse momentum and energy for Cu+Cu and Au+Au collisions from the PHOBOS experiment. New data on elliptic flow in Cu+Cu collisions at are shown. Elliptic flow scaled by participant eccentricity is found to be similar for both systems when collisions with the same number of participants or the same average area density are compared. This similarity is observed over a wide range in pseudorapidity and transverse momentum, indicating that participant eccentricity is the relevant quantity for generating the azimuthal asymmetry leading to the observed elliptic flow.

The intermediate p_T region (2–5 GeV/c) in central Au+Au collisions at RHIC has a rich physics content. The (anti)proton to pion ratio at the intermediate p_T gives us a powerful tool to investigate the bulk properties of the hot and dense matter created at RHIC and their hadronization processes. We present the preliminary results of identified charged hadron spectra at the lower beam energies at RHIC. The excitation function of (anti)proton to pion ratios from SPS to RHIC is shown. We also discuss the onset of the baryon enhancement at the high energy heavy ion collisions.

We report first measurements of elliptic flow (v₂) fluctuations for the STAR collaboration at middle rapidity in collisions. We analyse the multiplicity dependence of the flow vector length distribution to disentangle non-flow correlations from v₂ fluctuations. We find that the width of the v₂ distribution is approximately 36% of the mean v₂ and, within errors, independent of collision centrality. This value coincides with eccentricity fluctuations, apparently leaving little room for other sources of fluctuations.

We present measurements by STAR of the anisotropic flow coefficients v₂ and v₄ as a function of particle-type, centrality, transverse momentum and pseudorapidity in Au+Au collisions at RHIC.

We present first results on event-by-event elliptic flow fluctuations in Au+Au collisions at obtained with the PHOBOS detector. Over the measured range in centrality, large relative fluctuations of 40–50% are found. The elliptic flow fluctuations are well described as being proportional to fluctuations in the shape of the initial collision region, as estimated event by event with the participant eccentricity using Glauber Monte Carlo.

Recent surveys of multiplicity fluctuations, transverse momentum fluctuations and two-particle azimuthal correlations are presented for several collision systems as a function of centrality and transverse momentum. Both multiplicity and transverse momentum fluctuations exhibit a power-law scaling as a function of the number of participants that is independent of the collision system. Although these observations are consistent with critical behaviour, the critical exponent η measured using azimuthal correlations is seen to be independent of centrality and collision system. Also observed in the azimuthal correlations is a displaced away-side peak in central Au+Au collisions when the pairs are restricted to low transverse momentum.

The cooling storage ring, to be built at Lanzhou, will be able to deliver heavy ion beams up to uranium up to 0.52 GeV/u. It is expected to make considerable contribution to nuclear EOS study in the high net baryon-density region. With a relativistic transport model, we performed simulations for U+U collisions with different orientations. It is shown that by combining the forward neutron multiplicity and an event-wise elliptic flow selection, it is possible to identify the tip–tip and body–body head-on collisions. The effective identification of these two extreme configurations will allow us to study the EOS at the highest baryon density in the U+U collisions.

We present the first measurements of the transverse momentum spectra and mid-rapidity yields of the Ξ⁰(1530) multi-strange baryon resonance, from collisions at RHIC from the STAR experiment. Ratios of the mid-rapidity yield of this long-lived (cτ = 21 fm) resonance to its non-resonance partner (the Ξ baryon) are compared to predictions from thermal models and to the corresponding ratios for other resonances previously reported by STAR. Conclusions will be drawn about the implication of these measurements for the time between chemical and thermal freeze-out (Δt_therm-chem) and any observed deviations from the expected mass and width will be discussed.

The PHENIX experiment at RHIC has measured production of ω- and ϕ-mesons in p + p, d + Au and Au+Au collisions at and 200 GeV. Transverse momentum (mass) spectra measured in hadronic and di-electron decay channels are found to be in agreement with each other within the errors. Nuclear modification factors R_AA measured for both mesons are consistent with results obtained for other neutral mesons. The position of the meson mass peaks and their widths reconstructed in hadronic decay channels are in agreement with their properties measured in vacuum.

We present results on two-particle azimuthal correlations with strange trigger particles (K⁰_S, Λ, Ξ, Ω) associated with unidentified charged particles in d+Au and Au+Au collisions at . We investigate, in detail, the near-side associated yield as a function of centrality, p_T and strangeness content in the trigger particle to look for possible flavour and baryon/meson differences. We compare our results to a fragmentation and recombination model, where the study of Ω-triggered correlations is used as a critical test of the validity of the recombination picture.

We present the centrality dependence of the N(Ω)/N(ϕ) ratios and ϕ v₂ measured in Au+Au collisions at by the STAR experiment at RHIC. The results are compared to measurements of other identified particles and recombination model expectations in order to gain insight into the partonic collectivity and possible thermalization of the produced medium.

Heavy-quark production in high-energy proton–nucleus (pA) collisions is described in the framework of the colour glass condensate. k_⊥ factorization is broken even at leading order albeit a more general factorization in pA holds at this order in terms of two-, three- and four-point correlators of Wilson lines in the nuclear target. The x-evolution of these correlators is computed in the large A and large N mean-field limit of the Balitsky–Kovchegov equation. We show results for heavy-quark production at RHIC and LHC energies.

Heavy quarks will be abundantly produced in Heavy Ion Collisions at LHC energies. Both the production of open heavy flavoured mesons and quarkonia will probe the strongly interacting medium created in these reactions. In particular, the ALICE detector will be able to measure heavy flavour production down to low transverse momentum, combining leptonic and hadronic channels, covering a large rapidity range |η| < 0.9 and −4 < η < −2.5. In this talk we will present the main physics motivations for the study of heavy flavour production at LHC energies and some examples of physics analyses developed by the heavy flavour working group of ALICE.

The main focus of the heavy flavour programme at RHIC is to investigate the properties of the dense matter produced in heavy-ion collisions by studying its effect on open heavy flavour and quarkonia production. This in turn requires a detailed understanding of their production in elementary p+p collisions so that the dense matter effects can be later unfolded. In this paper, we present the first midrapidity cross section measurement of bottomonium at with the STAR experiment. We compare our results with perturbative QCD calculations. A brief status on the study of charmonium in STAR is given.

Recent results of the NA49 Collaboration are discussed. These include the energy dependence of stopping and the production of the light fragments t and ³He. New data on the system size dependence of hyperon production at 40A and 158A GeV are also presented.

I present here a new Glauber-inspired approach to derive normal cold nuclear matter effects on J/ψ production in Au–Au collisions. In an as much as possible model-independent way, it extrapolates the centrality-dependent yields from d-Au to Au–Au collisions. I then compare the new Au–Au measurements shown by the PHENIX experiment in this conference. In the most central collisions, J/ψ survival probabilities beyond cold nuclear matter effects are found to be 44 ± 23% at forward (y = 1.7) and 25 ± 12% at mid (y = 0) rapidities.

Particle yields in heavy ion collisions show an overwhelming evidence for chemical or relative chemical equilibrium at all beam energies. The rapidity dependence of the thermal parameters T and μ_B can now be determined over a wide range of rapidities and show a systematic behaviour towards an increase in μ_B away from mid-rapidity.

The recombination model is applied to the production of K, Λ, ϕ and Ω at all p_T in central Au+Au collisions. The thermal–shower component of the recombination is found to be important for K and Λ in the intermediate p_T region. For ϕ and Ω, the pure thermal recombination dominates up to 8 GeV/c. The contribution from shower strange quarks to multi-strange particle spectra can be seen from the Ω/Φ ratio.

Measurements of inclusive spectra of hadrons at large transverse momentum over a broad range of energy in different collision systems have been performed with the PHENIX experiment at RHIC. The data allow us to study the energy and system size dependence of the suppression observed in R_AA of high-p_T hadrons at GeV. Due to the large energy range from GeV to 200 GeV, the results can be compared to results from CERN SPS at a similar energy. The large Au+Au dataset from the 2004 run of RHIC also allows us to constrain theoretical models that describe the hot and dense matter produced in such collisions. Investigation of particle ratios such as η/π⁰ helps in understanding the mechanisms of energy loss.

Particle-type dependences of hadron yield suppression/enhancement patterns, especially its difference between mesons and baryons, at intermediate p_T (2–5 GeV/c) is one of the findings in heavy ion collisions at RHIC. A systematic study of identified hadron production was performed in Au+Au/Cu+Cu collisions at GeV, to investigate the possible origins of this difference. In this paper, we show particle ratios, nuclear modification factors and their scaling properties.

We utilize a 3D hybrid hydro+micro model for a comprehensive and consistent description of soft and hard particle production in ultra-relativistic heavy-ion collisions at RHIC. In the soft sector we focus on the dynamics of (multi-) strange baryons, where a clear strangeness dependence of their collision rates and freeze-out is observed. In the hard sector we study the radiative energy loss of hard partons in a soft medium in the multiple soft scattering approximation. While the nuclear suppression factor R_AA does not reflect the high quality of the medium description (except in a reduced systematic uncertainty in extracting the quenching power of the medium), the hydrodynamical model also allows us to study different centralities and in particular the angular variation of R_AA with respect to the reaction plane, allowing for a controlled variation of the in-medium path length.

We present the first measurement of the away-side hadron yield associated with high-p_T direct photons in p+p collisions at GeV. Widths of electromagnetic showers measured by a shower maximum detector (SMD) in the STAR barrel electromagnetic calorimeter (BEMC) have been used to select events rich in direct photons in pp collisions at the RHIC top energy. The measured associated hadron yield opposite to the trigger agrees with Hijing calculations.

With the QGP opacity computed perturbatively and with the global entropy constraints imposed by the observed dN_ch/dy ≈ 1000, radiative energy loss alone cannot account for the observed suppression of single non-photonic electrons. Collisional energy loss is comparable in magnitude to radiative loss for both light and heavy jets. Two aspects that significantly affect the collisional energy loss are examined: the role of fluctuations and the effect of introducing a running QCD coupling as opposed to the fixed α_s = 0.3 used previously.

We present a study of low- and intermediate-p_T correlated azimuthal angular distributions in Au+Au collisions at from STAR. The near side associated yields in Au+Au collisions are found to be strongly enhanced, due to contributions from large Δη. The enhancement is reduced for high p^trig_T. We show a strong broadening and enhancement of the away-side yield. The evolution of the away-side shape may be explained as the sum of a broad structure from bulk response and a narrow peak from jet fragmentation.

A model to simulate the jet quenching effect in ultrarelativistic heavy ion collisions is presented. The model is the fast Monte Carlo tool implemented to modify a standard PYTHIA jet event. The model has been generalized to the case of the 'full' heavy ion event (the superposition of soft, hydro-type state and hard multi-jets) using a simple and fast simulation procedure for soft particle production. The model is capable of reproducing the main features of the jet quenching pattern at RHIC and is applied to analyse novel jet quenching features at LHC.

We present results on two-particle angular correlations in p+p and Cu+Cu collisions over a broad range of (η, ϕ). The PHOBOS detector has a uniquely large angular coverage for inclusive charged particles. This allows for the study of correlations on both long- and short-range pseudorapidity scales. A complex two-dimensional correlation structure emerges which is interpreted in the context of a cluster model. The cluster size and its decay width are extracted from the two-particle pseudorapidity correlation function. Relative to p+p collisions, Cu+Cu reactions show a non-trivial decrease of cluster size with increasing centrality. These results may provide insight into the hadronization stage of the hot and dense medium created in heavy-ion collisions.

The first 3D calculation of shock wave propagation in a homogeneous QGP has been performed within the new formulation of relativistic dissipative hydrodynamics which preserves the causality. We found that the relaxation time plays an important role and also affects the angle of the Mach cone.

When studying the initial state and evolution of the matter created in relativistic heavy ion collisions, high-p_T direct photons are a powerful probe. They are created in initial hard processes and in parton fragmentation, and possibly in interactions of partons with the hot and dense medium. We present systematic measurements of high-p_T direct photon production in GeV p+p and Au+Au collisions. The nuclear modification factor of direct photons is shown for 5 < p_T < 18 GeV/c, and at very high transverse momenta it seems to be below unity in the most central Au+Au collisions.

We discuss the emission of high momentum lepton pairs (p_T > 4 GeV) with low invariant masses (M ≪ p_T) in central Au+Au collisions at RHIC ( GeV). The spectra of dileptons produced through interactions of quark and antiquark jets with the quark-gluon plasma (QGP) have been calculated. Annihilation and Compton scattering processes, as well as processes benefitting from collinear enhancement, including Landau–Pomeranchuk–Migdal (LPM) effects, are calculated and convolved with a one-dimensional hydrodynamic expansion. The jet-induced contributions are compared to thermal dilepton emission and Drell–Yan processes, and are found to dominate around p_T = 4 GeV.

The NA60 experiment at the CERN SPS has studied low-mass muon pairs in 158 AGeV In–In collisions. A strong excess of pairs is observed above the yield expected from neutral meson decays. The unprecedented sample size of close to 400K events and the good mass resolution of about 2% have made it possible to isolate the excess by subtraction of the decay sources (keeping the ρ). The shape of the resulting mass spectrum exhibits considerable broadening, but essentially no shift in mass. The acceptance-corrected transverse-momentum spectra have a shape atypical for radial flow and show a significant mass dependence, pointing to different sources in different mass regions.

The high granularity pixel vertex tracker of the NA60 experiment can distinguish between prompt muon production and semi-leptonic decays of open charm. This clarifies the origin of the dimuon excess measured by NA50 in the 1.2–2.7 GeV/c² mass range in Pb–Pb collisions. Preliminary results from NA60, obtained in In–In collisions at 158 GeV/nucleon, have shown that the excess is due to prompt dimuons. We present here the most recent results, obtained using the full statistics, with a significant improvement of the off-vertex decay tagging capabilities, due to a better detector alignment. Results on multiplicity and p_T dependences of both charm and prompt dimuon contributions are presented here for the first time.

Results are presented from an ongoing analysis of direct photon production with the STAR experiment at RHIC. The direct photon measurement in d+Au collisions and the π⁰ spectrum in p+p collisions are found to be in agreement with NLO pQCD calculations.

Photon-tagged correlations may be useful to determine how the dense partonic medium produced in heavy-ion collisions affects the fragmentation of high-energy quarks and gluons into a leading hadron. In these proceedings, I discuss the kinematic requirements for the hadron and the prompt photon transverse momentum cuts. A case study at LHC energy, tagging on and photons, is then briefly examined.

We report on a measurement of electron pair production in ¹²C+¹²C collisions at an incident energy of 2 GeV per nucleon with the HADES spectrometer. The measured pair production probabilities span over five orders of magnitude from the π⁰-Dalitz to the ρ/ω invariant-mass region. Dalitz decays of π⁰ and η account for all the yield up to 0.15 GeV/c², but for only about 50% above this mass. The excess yield is in agreement with the former DLS result if one assumes that it scales with beam energy like pion production. A preliminary analysis of ¹²C+¹²C collisions at an incident energy of 1 A GeV, measured with the HADES detector, supports this scenario.

Recently the NA60 collaboration has presented high precision measurements of dimuon spectra double differential in invariant mass M and transverse pair momentum p_T in In–In collisions at 158 A GeV. While the M-dependence is important for an understanding of in-medium changes of light vector mesons and is p_T integrated insensitive to collective expansion, the p_T-dependence arises from an interplay between emission temperature and collective transverse flow. This fact can be exploited to derive constraints on the evolution model and in particular on the contributions of different phases of the evolution to dimuon radiation into a given M window. We present arguments that a thermalized evolution phase with T > 170 MeV leaves its imprint on the spectra.

We summarize our current theoretical understanding of in-medium properties of the electromagnetic current correlator in view of recent dimuon data from the NA60 experiment in In(158 AGeV)–In collisions at the CERN-SPS. We discuss the sensitivity of the results to spacetime evolution models for the hot and dense partonic and hadronic medium created in relativistic heavy-ion collisions and the contributions from different sources to the dilepton-excess spectra.

The dielectron continuum is rich in physics signals including vector meson decays and correlated semi-leptonic heavy flavour decays. The PHENIX analysis suggests the following: a possible excess in the low mass region of the central Au+Au spectra over the reference cocktail and a suppression pattern in the intermediate region, where correlated charm dominates. The status of the Cu+Cu analysis is also presented.

The invariant mass spectra of e⁺e⁻ pairs produced in 12 GeV p+A reactions are measured at the KEK Proton Synchrotron. We observed a significant enhancement over the known hadronic sources on the low-mass side of the ω meson peak for C and Cu data. The 95% CL allowed parameter regions for ρ/ω ratio are obtained as ρ/ω< 0.15 and ρ/ω< 0.31 for C and Cu targets, respectively. As for the ϕ meson, the data obtained with a Cu target revealed a significant excess on the low-mass side of the ϕ meson peak mainly in the βγ_ϕ < 1.25 region.

The coalescence of protons and neutrons into deuterons is sensitive to the spacetime extent of the baryon freeze-out region. Several experiments have measured the coalescence parameter, B₂, at mid-rapidity. BRAHMS has extended these measurements to forward rapidities and thus studied the longitudinal dependence of the freeze-out volume. At near mid-rapidity the coalescence parameter is the same for baryons and anti-baryons and similar in magnitude to lower energy results. We also find that B₂ remains constant from y = 0 to y = 3.2.

Recent PHENIX elliptic flow (v₂) measurements for identified particles produced in Au+Au and Cu+Cu collisions at are presented and compared to other RHIC measurements. They indicate universal scaling of v₂ compatible with partonic collectivity leading to the flow of light, strange and heavy quarks with a common expansion velocity field.

We present elliptic flow v₂ as a function of freeze-out time, transverse momentum for π, K, nucleon, Λ, Ξ and Ω in Au+Au collisions at within two transport approaches (RQMD and UrQMD). The presence of mass ordering and NCQ scaling in the string-hadron model suggests that hadronic interactions do contribute to the observed particle-type dependence of v₂ as well.

Ultra-relativistic heavy-ion collisions at an energy are studied in a three-dimensional fluid dynamical model. The results of a hydrodynamical evolution using the PIC-method are shown. The importance and diagnostic value of a proper reaction plane determination is emphasized, and the time development of collective observables is presented.

Elliptic flow has been measured by the BRAHMS experiment as a function of transverse momentum and pseudorapidity for the Au+Au reaction at GeV. Identified-particle v₂(η, p_t) values were obtained with the two BRAHMS spectrometers at pseudorapidities η≈ 0, 1 and 3.4. The results show that the differential v₂(η, p_t) values for a given particle type are essentially constant over the covered pseudorapidity range. It is suggested that the dominant cause of the observed fall-off of the integral v₂ values going away from mid-rapidity is a corresponding softening of the particle spectra.

We present the transverse momentum spectra at mid-rapidity for d, (1 < p_T < 4 GeV/c) and (2 < p_T < 6 GeV/c) measured by the STAR experiment at RHIC and extract the coalescence parameters B₂ and B₃, respectively. We also present the v₂ measurement for and . We find that the and follow the atomic mass number A scaling within errors and a negative v₂ has been observed for at low p_T.

We present STAR's measurements of directed flow for charged hadrons in Au+Au and Cu+Cu collisions at GeV and 62.4 GeV, as a function of pseudorapidity, transverse momentum and centrality. We find that directed flow depends on the incident energy, but not on the system size. We extend the validity of limiting fragmentation hypothesis to different collision systems.

We present the centrality dependence of Λ and hyperon global polarization in Au+Au collisions at GeV and 200 GeV measured with the STAR detector at RHIC. Within the precision of the measurement, we observe no centrality dependence of Λ and hyperon global polarization, and within our acceptance it is consistent with zero. Different sources of systematic uncertainties (feed down effects, spin precession) are discussed and estimated. The obtained upper limit, , is compared to theoretical predictions discussed recently in literatures.

New results on antiparticle to particle ratios in Cu+Cu and Au+Au collisions at = 62.4 and 200 GeV from the PHOBOS experiment at RHIC are presented. Transverse momentum spectra of pions, kaons, protons and antiprotons from Au+Au collisions at = 62.4 GeV close to mid-rapidity are also discussed. Antiparticle to particle ratios are found to be remarkably independent of the collision centrality in both colliding systems. The collision energy dependence of the ratios is very significant in Cu+Cu collisions. Baryons are found to have substantially harder transverse momentum spectra than mesons. The p_T region in which the proton to pion ratio reaches unity in central Au+Au collisions at = 62.4 GeV fits into a smooth trend as a function of collision energy. The observed particle yields at very low p_T are comparable to extrapolations from higher p_T for kaons, protons and antiprotons. The net proton yield at mid-rapidity is found to be proportional to the number of participant nucleons in Au+Au collisions at 62.4 and 200 GeV energies.

The NA49 experiment has acquired a huge data set of Pb+Pb events over a broad range of energy at CERN SPS. This high statistics data set, coupled with a state-of-the-art analysis technique, allows for the first model-independent extraction of 3D two-pion emission sources at SPS energies. These sources provide new insights into the nature of a long-range source previously reported by PHENIX at RHIC. The new results indicate that the pion source displays significant non-Gaussian tails in the longitudinal direction at 40 and 158 A GeV and in the outward direction at 158 A GeV.

Two-charge-particle azimuthal correlations (TCPAC) and the azimuthal charge balance function (ACBF) are compared with anisotropic flow by using transport models, RQMD and AMPT. In these two models, TCPAC has the same centrality dependence as anisotropic flow. The momentum conservation contributes only back-to-back correlations in TCPAC, which are well separated from small angle correlations caused by anisotropic transverse momentum distribution, while the centrality dependence of ACBF is different from those of anisotropic flow and TCPAC. This indicates that ACBF cannot be used as another presentation of anisotropic flow, as expected from thermal models.

A listing of members of the PHENIX Collaboration is given in the PDF file.

A listing of members of the STAR Collaboration is given in the PDF file.

A listing of members of the BRAHMS Collaboration is given in the PDF file.

A listing of members of the NA49 Collaboration is given in the PDF file.

A listing of members of the WA98 Collaboration is given in the PDF file.

A listing of members of the NA60 Collaboration is given in the PDF file.

A listing of members of the RBC-Bielefeld Collaboration is given in the PDF file.

A listing of members of the PHOBOS Collaboration is given in the PDF file.

A listing of members of the CLAS Collaboration is given in the PDF file.

A listing of members of the CMS Collaboration is given in the PDF file.

A listing of members of the CERES Collaboration is given in the PDF file.

A listing of members of the ALICE Collaboration is given in the PDF file.

The PDF file provided contains web links to all articles in this issue.