Table of contents

The 5th International Conference on Physics and Astrophysics of Quark Gluon Plasma (ICPAQGP 2005) was held on 8–12 February 2005 at the Variable Energy Cyclotron Centre and Saha Institute of Nuclear Physics campus, Kolkata, India. The conference was enriched by the august presence of about 300 participants representing 18 countries across the globe. It had plenary talks and oral presentations, which form a part of these proceedings. Besides invited and contributed talks there were also a large number of poster presentations.

The conference was energized by discussions of fresh experimental data from RHIC on strong elliptic flow, jet quenching, single photon spectra etc. Moreover, new theoretical results were brought to the discussion forum during this conference. Colour glass condensates, hydrodynamical flow, jet quenching and sQGP were intensely debated by the participants. The highlight of ICPAQGP 2005 was the presentation of fresh experimental results from the RHIC-IV run.

The ICPAQGP series, since its inception in 1988, has placed emphasis on the role of quark matter in the fields of astrophysics and cosmology. The subsequent conferences held in 1993, 1997, 2001 and 2005 had also retained this focus. The conference was preceded by a Fest Colloquium in honour of Professor Bikash Sinha. Professor Sinha, regarded as the pioneer in establishing quark gluon plasma research in India, has successfully encouraged a group of young Indian researchers to devote themselves wholeheartedly to QGP research—both theoretical and experimental.

Members of the International Advisory Committee played a pivotal role mainly in the selection of speakers. The contributions of the Organizing Committee in all aspects, from selecting the contributory talks posters down to arranging local hospitality, were much appreciated. We thank the members of both committees for making ICPAQGP 2005 an interesting platform for scientific deliberation.

The ICPAQGP 2005 was supported financially by the Board of Research in Nuclear Science of the Department of Atomic Energy, Government of India.

This is a short review of some theoretical aspects of the physics of ultra-relativistic heavy ion collisions. I review the main properties of the QCD phase diagram and recent developments in the physics of high gluon densities in the hadronic wavefunctions at high energy. Then I comment salient results obtained at RHIC.

The 'Little Bangs' made in particle collider experiments reproduce the conditions in the Big Bang when the age of the Universe was a fraction of a second. It is thought that matter was generated, the structures in the Universe were formed and cold dark matter froze out during this very early epoch when the equation of state of the Universe was dominated by the quark-gluon plasma (QGP). Future Little Bangs may reveal the mechanism of matter generation and the nature of cold dark matter. Knowledge of the QGP will be an essential ingredient in quantitative understanding of the very early Universe.

Recent results from the PHENIX Collaboration on Au+Au and d+Au collisions at the Relativistic Heavy Ion Collider.

A brief overview of the current results and conclusions from the PHOBOS experiment at the Relativistic Heavy Ion Collider (RHIC) is given. No evidence is found for non-monotonic behavior of observables measured by PHOBOS in the RHIC energy region. Convincing evidence is found that we have created a state of matter with high energy-density, that is nearly net-baryon free and is strongly interacting. The data are found to exhibit "simple" scaling behaviors, which include extended longitudinal scaling and scaling with the number of participating nucleons. The Au+Au collision charged particle data also exhibit a remarkable factorization of collision energy and geometry.

A brief review of BRAHMS measurements of bulk particle production in RHIC Au+Au collisions at √s_NN = 200GeVis presented, together with some discussion of baryon number transport. Intermediate pT measurements in different collision systems (Au+Au, d+Au and p+p) are also discussed in the context of jet quenching and saturation of the gluon density in Au ions at RHIC energies. This report also includes preliminary results for identified particles at forward rapidities in d+Au and Au+Au collisions.

Contribution of a preshower photon multiplicity detector to the physics of ultra-relativistic nuclear collisions is reviewed and future possibilities at RHIC and LHC are discussed.

Dramatic changes had occurred with our understanding of Quark-Gluon Plasma, which is now believed to be rather strongly coupled, sQGP for short. Hydrodynamical behavior is seen experimentally, even for rather small systems (rather peripheral collisions). From elliptic flow the interest is shifting to even more sophysticated observable, the conical flow, created by quenched jets. The exact structure of sQGP remains unknown, at the moment the best picture seem to be a liquid made partly of binary bound states. As we discuss at the end, those can be possibly seen in the dilepton spectra, as "new vector mesons" above T_c.

The Color Glass Condensate is a theory of the dynamical properties of partons in the Regge limit of QCD: x_Bj → 0, Q² >> Λ²_QCD = fixed and the center of mass energy squared s→ infty. We provide a brief introduction to the theoretical ideas underlying the Color Glass Condensate. We also discuss how these ideas provide a unified framework to discuss both Deeply Inelastic Scattering (DIS), and hadronic collisions (from pp to AA) in QCD.

We describe application of saturation/Color Glass Condensate physics to heavy ion collisions, concentrating on several important observables. We show how simple saturationinspired assumptions about particle production in heavy ion collisions allow one to accurately describe total charged particle multiplicity as a function of the collision's centrality, of the center of mass energy, and of the particle rapidity. We will then describe how predictions of saturation physics can be tested by studying energy/rapidity dependence of particle spectra in p(d)A collisions. We concentrate on the nuclear modification factor R^pA for gluon production. We show that at moderately high energy/rapidity the nuclear modification factor R^pA exhibits Cronin enhancement. As the energy/rapidity increases, R^pA decreases. At sufficiently high energy/rapidity R^pA becomes less than 1 for all values of p_Tindicating the onset of suppression of gluon production due to quantum evolution effects. These predictions were confirmed by RHIC data.

I present our recent results on the critical end point in the μ_B-Tphase diagram of QCD with two flavours of light dynamical quarks and compare them with similar results from other groups. Implications for a possible energy scan at the RHIC are discussed. I also comment briefly on the new results of great relevance to heavy ion collisions from finite temperature lattice QCD simulations on speed of sound, specific heat and on the fate of J/ψ.

An overview of the physics of event by event fluctuations in heavy ion collisions is provided. We will discuss what the measurement of fluctuations and correlation can tell us about the system created in these collisions.

Studies of charged hadron multiplicities have provided important information about the physics of ultra-relativistic heavy ion collisions. The systematics of charged particle multiplicities in high energy collisions, i.e. nucleon-nucleon, e⁺ e⁻and nucleus-nucleus reactions, as a function of collision energy and centrality, suggest that in heavy ion collisions the multiplicity distributions are determined in the initial collision stage and that the overall produced multiplicity is limited by coherence or destructive interference in this early stage. In this paper, I will present some of the experimental results supporting these conclusions and point out features of the data that still await an explanation in dynamical models of the collision process. I will discuss future possibilities to help answer these questions, including measurements at the Large Hadron Collider and studies of multiplicity correlations.

Correlations and fluctuations (the latter are directly related to the 2-particle correlations) is one of the important directions in analysis of heavy ion collisions. At the current stage of RHIC exploration, when the details matter, basically any physics question is addressed with help of correlation techniques. In this talk I start with a general introduction to the correlation and fluctuation formalism and discuss weak and strong sides of different type of observables. In more detail, I discuss the two-particle p_Tcorrelations/⟨p_T⟩ fluctuations. In spite of not observing any dramatic changes in the event-by-event fluctuations with energy, which would indicate a possible phase transition, such correlations measurements remain an interesting and important subject, bringing valuable information. Lastly, I show how radial flow can generate characteristic azimuthal, transverse momentum and rapidity correlations, which could qualitatively explain many of recently observed phenomena in nuclear collisions.

Parton propagation in dense nuclear matter results in elastic, inelastic and coherent multiple soft scattering with the in-medium color charges. Such scattering leads to calculable modifications of the hadron production cross section that is evaluated in the framework of the perturbative QCD factorization approach. Final state medium-induced gluon bremsstrahlung is arguably the most efficient way of suppressing large transverse momentum particle production in nucleus-nucleus collisions. The observed hadronic attenuation, known as jet quenching, can be related to the properties of the medium, such as density and temperature, and carries valuable information about the early stages of heavy ion reactions. Non-Abelian energy loss in the quarkgluon plasma can be studied in much greater detail through the modification of the two particle back-to-back correlations. Perturbative calculations give good description of the redistribution of the lost energy in lower transverse momentum particles and predict significant increase of the correlation width of away-side di-hadrons. In contrast, energy loss in cold nuclear matter was found to be small but for large values of Feynman-x is expected to complement the dynamical higher twist shadowing in experimentally observable forward rapidity hadron suppression.

After five years of data taking, the STAR experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory provides precise measurements of particle production at high transverse momentum in p-p, d-Au, and Au-Au collisions at √S_NN = 200 GeV. We review recent results on the flavor dependence of high pT particle suppression and hadron particle spectra at √S_NN = 62.4 GeV. New results on two-particle angular correlations for identified trigger particles and for low momentum associated charged hadrons in p-p and Au-Au as well as near-side .Δη correlations will be presented and discussed.

In this report I will give an experimental overview on nuclear stopping in hadron collisions, and relate observations to understanding of baryon transport. Baryon number transport is not only evidenced via net-proton distributions but also by the enhancement of strange baryons near mid-rapidity. Although the focus is on high-energy data obtained from pp and heavy ions from RHIC, relevant data from SPS and ISR will be considered. A discussion how the available data at higher energy relates and gives information on baryon junction, quark-diquark breaking will be made.

Electromagnetic measurements have been playing unique roles in the studies with high-energy heavy collisions. Many interesting results have been obtained in the recent RHIC experiments, which have been providing key information on the interpretation and understanding of the hot and dense nuclear matter created in the ultra-relativistic heavy ion collisions. In this article, some of the recent results are picked up, and implications of these results are discussed.

Photon production from hadronic matter is reviewed. It is shown that photon yield from baryon-meson reactions is substantial. The role of a₁ meson in π ρ → π γ is discussed in detail and it is observed that a₁ mediated processes contribute the most. The production rates of photon from hadronic matter and quark matter has been compared.

I discuss the Color Glass Condensate as a media. I argue that Pomerons, Odderons and Reggeons are the small fluctuation excitations of this media. I argue that understanding the effects of Pomeron loops leads to the idea that this media has a duality symmetry. I discuss the implications of the Color Glass Condensate for the initial conditions at RHIC.

I first discuss the NLO QCD calculation for the dissociation cross section of J/ψ into open charm, which shows a large second order correction near the threshold. The large correction softens when effective thermal masses in the order of the binding energy are introduced for the quarks and gluons. Hence, with the thermal masses, the method is reliably applied to calculate the dissociation cross section of J/ψ, which according to recent lattice results seems to remain bound even up to 1.6 × T_c. The dominant contribution to the dissociation comes from the thermal gluons, while the effects due to thermal quarks are suppressed due to suppressed phase space. The relevance of this result is discussed in the context of RHIC and signature of QGP.

Strangeness flavor yield s and the entropy yield Sare the observables of the deconfined quark-gluon state of matter which can be studied in the entire available experimental energy range at AGS, SPS, RHIC, and, in near future, at the LHC energy range. We present here a comprehensive analysis of strange, soft hadron production as function of energy and reaction volume. We discuss the physical properties of the final state and argue how evidence about the primordial QGP emerges.

The advent of RHIC has opened up the possibilities for a greater understanding of the hadronization process in relativistic heavy ion collisions. The large volume of data collected, together with high collisions energies, allows us to address both strangeness and charm production in great detail. This paper will present results on bulk strangeness production in Au+Au collisions at √S_NN = 200 GeV, in particular on strangeness enhancement and strange quark scaling. Also presented are results on strange particle ratios and elliptic flow measurements in the intermediate pT region, together with comparisons with theoretical models. An excitation function of strangeness yields and ratios are also presented with reference to the newly acquired Au+Au data at √S_NN = 62.4 GeV.

Also presented in this paper are the first results on charm production measured in STAR. Utilising the methods of reconstructing D mesons through their leptonic channels, the crosssection for charm production in d+Au collisions at √S_NN = 200 GeV is presented. Also shown is a first measurement of the elliptic flow of charmed mesons.

I will first present the vacuum for the e⁺-e⁻ field of QED and show how it is modified for baryons in nuclear environment. Then I discuss the possibility of producing new types of nuclear systems by implanting an antibaryon into ordinary nuclei. The structure of nuclei containing one antiproton or antilambda is investigated within the framework of a relativistic mean-field model. Self-consistent calculations predict an enhanced binding and considerable compression in such systems as compared with normal nuclei. I present arguments that the life time of such nuclei with respect to the antibaryon annihilation might be long enough for their observation. This yields a mechanism for cold compression.

We discuss a model for the energy source of gamma-ray burst which is based on the "delayed conversion" of a metastable pure hadronic compact star ("neutron star") to a quark star (hybrid star or strange star).

The determination of mass and radius of a single neutron star EXO 0748-676 has been reported recently. Also, the estimate of radius from the measurement of moment of inertia of pulsar A in double pulsar system PSR J0737-3039 would be possible in near future. Here we construct models of static and uniformly rotating neutron stars involving exotic matter and compare our theoretical calculations with the recent findings from observations to probe dense matter in neutron stars.

We investigate the phase diagram of strange quark matter in beta equllibrium where the lighter up and down quarks form the two flavor superconducting matter whereas the strange quark remains unpaired. This is studied wihin a Nambu-Jona-Lasinio model. The variational method as used here allows us to investigate simultaneous formation of condensates in quark-antiquark as well as in diquark channels. Color and electric charge neutrality conditions are imposed in the calculation of the thermodynamic potential. Medium dependance of strange quark mass plays a sensitive role in maintaining charge neutrality conditions. At zero temperature the system goes from the gapless phase to the usual BCS phase through an intermediate normal phase as density is increased. However, at higher temperature the gapless to BCS transition becomes a smooth transition. The gapless modes show a smooth behaviour with respect to temperature vanishing above a critical temperature which is larger than the BCS transition temperature.

This talk summarizes the present status of a program to quantitatively relate data from the Relativistic Heavy Ion Collider (RHIC) on collective expansion flow to the Equation of State (EOS) of hot and dense strongly interacting matter, including the quark-gluon plasma and the quark-hadron phase transition. The limits reached with the present state of the art and the next steps required to make further progress will both be discussed.

We update briefly our understanding of hadron production in relativistic nucleus-nucleus collisions in terms of statistical models with emphasis on the relation of the data to the QCD phase boundary and on a puzzle in the beam energy dependence.

After a brief introduction to the physics of high-energy nuclear collisions, we will present recent experimental results that are closely connected to the properties of the matter produced in Au+Au collisions at RHIC. Collective motion with parton degrees of freedom is called partonic collectivity. We will focus on collective observables such as transverse radial flow and elliptic flow. With experimental observations, we will demonstrate that, at RHIC, collectivity has already been developed prior to the hadronic stage. Finally, we will develop a plan for future measurements that are needed for characterization of the partonic Equation of State in high-energy nuclear collisions.

In the framework of the Mueller-Israel-Stewart theory of dissipative fluid dynamics, we have studied the space-time evolution of a QGP fluid. For simplicity, we have considered shear viscosity only and neglected bulk viscosity and heat conductivity. Shear viscosity opposes the expansion and cooling of the fluid. As a result, the lifetime of the fluid is extended. We also find that the parton p_Tdistribution is considerably flattened.

A brief review is given on the discovery and the first five decades of the Hanbury Brown–Twiss effect and its generalized applications in high energy nuclear and particle physics, that includes a meta-review. Interesting and inspiring new directions are also highlighted, including for example source imaging, lepton and photon interferometry, non-Gaussian shape analysis as well as many other new directions. Existing models are compared to two-particle correlation measurements and the so-called RHIC HBT puzzle is resolved. Evidence for a (directional) Hubble flow is presented and the conclusion is confirmed by a successful description of the pseudorapidity dependence of the elliptic flow as measured in Au+Au collisions by the PHOBOS Collaboration.

STAR observes a complex picture of RHIC collisions where correlation effects of different origins–initial state geometry, semi-hard scattering, hadronization, as well as final state interactions such as quantum intensity interference - coexist. Presenting the measurements of flow, mini-jet deformation, modified hadronization, and the Hanbury Brown and Twiss effect, we trace the history of the system from the initial to the final state. The resulting picture is discussed in the context of identifying the relevant degrees of freedom and the likely equilibration mechanism.

Parton recombination models have been very successful in explaining data taken at RHIC on hadron spectra and emission patterns in Au+Au collisions at transverse momenta above 2 GeV/c, which have exhibited features which could not be understood in the framework of basic perturbative QCD. In this article I will review the current status on recombination models and outline which future challenges need to be addressed by this class of models.

The new conditions which will be reached when LHC will collide lead ions are discussed together with the probes which will become available for studying the properties of the hottest matter ever formed in the laboratory. The experimental requirements and how the LHC experiments, in particular ALICE, will face the challenges are presented.

This paper gives highlights of the experimental results shown at this conference.

Results from various theoretical approaches and ideas presented at this exciting meeting are reviewed. I also point towards future directions, in particular hydrodynamic behaviour induced by jets traveling through the quark-gluon plasma, which might be worth looking at in more detail.

Kaons, as the main carriers of strangeness, make for an important probe of the medium produced in relativistic heavy ion collisions. By topologically reconstructing the charged kaons, we reach high transverse momentum limits not presently accessible with the traditional reconstruction methods. We present recent results on nuclear modification factors involving charged kaons from three collision systems: p+p, d+A and Au+Au at 200GeV center of mass energy. A comparison to other strange mesons and baryons will be made and conclusions on medium properties, particle production mechanisms, initial and final state effects will be presented.

The production of Δ++ resonance in d+Au collisions at √s_NN = 200 GeV is investigated using the data taken by the STAR detector at RHIC. Systematics of Δ++ resonance production relative to p and yields have been studied. The nuclear modification factor R_CP, defined in terms of the ratio of Δ++ yields for central to peripheral data shows a rise in the intermediate p_Tregion, in line with Cronin enhancement.

We present the first measurement of multiplicity and pseudorapidity distributions of photons in the pseudorapidity region 2.3 ⩽ η ⩽ 3.7 for different centralities in Au + Au collisions at √s_NN = 62.4 GeV. The pseudorapidity distribution of photons, dominated by neutral pion decays, has been compared to those of identified charged pions, photons, and inclusive charged particles from heavy ion and nucleon-nucleon collisions at various energies. Scaling of photon yield with number of participating nucleons and limiting fragmentation scenario for inclusive photon production has been studied.

Particle multiplicities have yielded some of the most interesting insights at RHIC (Relativistic Heavy Ion Collider). To study the initial state effects at RHIC, we need to look at the small-x region in the gold nucleus, which can be achieved by going to forward rapidities (in the deuteron going direction) for d+Au collisions at √s_NN = 200 GeV. We measure charged hadrons at forward and backward rapidities using the PHENIX north and south muon arms for d+Au collisions at √s_NN = 200 GeV. We observe a Cronin-like enhancement on the gold going direction and a suppression on the deuteron going direction. This is qualitatively consistent with the expectation of shadowing/saturation type effects in the small-x region, which is probed at forward rapidities. However the enhancement at backward rapidities has not been explained.

The measurement of direct photons in √s_NN = 200 GeV p+pand Au+Au collisions is presented. The signal is compared to NLO pQCD calculations, which, in case of Au+Au, are scaled with the number of underlying nucleon-nucleon collisions. The agreement of the calculation with the data in both cases confirms the scaling of hard processes with the number of nucleon-nucleon collisions and supports the explanation of the earlier-observed pion suppression as a final-state effect.

Single electrons from open heavy quarks and di-leptons from J/ψ mesons have been studied systematically at RHIC/PHENIX using data from p+p, d+Au and Au+Au collisions at √s_NN = 62.4 GeV, 130 GeV and 200 GeV. From the single electron study, the charm quark yield is found to scale with the number of binary collisions. This scaling has recently been confirmed using Au+Au collisions at 62.4 GeV. A new analysis shows that a high p_T suppression of single electrons is observed in Au+Au collisions at 200 GeV. This suppression suggests that heavy quarks lose significant energy in the medium. A weak rapidity dependence is seen in J/ψ yields from d+Au data, which can be interpreted as a cold matter effect. We report also the results of a measurement of the spin alignment of the J/ψ in the p_T range around 1.5 GeV/c.

Two particle azimuthal correlation functions are used to study flow and jet fragmentation in the hot QCD matter believed to be created in Au+Au collisions at RHIC (√s_NN = 200GeV). Detailed results on jet topologies and yields, and their flavor dependence are obtained via a novel technique for decomposition of the combined correlations from jets and flow in Au+Au collisions. The results indicate significant broadening of the away-side jet attributable to important interactions between the flowing medium and the scattered partons which fragment into jets.

We present the preliminary results of event by event fluctuation in K/π ratio in Au+Au collision at √s_NN = 200 GeV and at 62.4 GeV using STAR detector at RHIC. Two different methods have been used to extract the dynamical fluctuation. The results from the study of energy and centrality dependence of the dynamical fluctuation are presented. From the excitation function it is seen that at two RHIC energies the measure of dynamical fluctuation is constant with values very close to that at 12.3 GeV at SPS. The dynamical fluctuation is found to be positive and decreasing with increasing centrality at RHIC. The results are compared with those from HIJING model calculation with jets. Results from HIJING are found to be very close to data from central collisions whereas it over predicts the data for peripheral events.

We present evidence for an onset of deconfinement at low SPS energies obtained by the NA49 experiment in central Pb+Pb collisions in an energy scan from 20 to 158 AGeV. As indicators for such an onset, the independence of mean mt on beam energy, a sharp peak in the strangeness-to-pion ratio and dynamical fluctuations in the event-by-event K/π ratio are discussed.

The NA60 experiment studies open charm and prompt dimuon production in proton-nucleus and nucleus-nucleus collisions at the CERN SPS. From June 2002 to November 2004 we collected data on dimuon production from proton-nucleus and Indium-Indium collisions. These data samples allow us to study low mass dimuon production (resonances and continuum), J/π suppression and open-charm production. We will also search for thermal dileptons, through the yield of "intermediate mass dimuons". In this paper we briefly overview some of the results obtained up to now, after shortly describing the detector.

The most recent and final results from the NA50 experiment on charmonia production in Pb-Pb interactions at 158 GeV/c per nucleon are presented. A strong J/ψ suppression is observed, which increases with the centrality of the collisions.

The J/ψ production is found to be anomalously suppressed starting at mid-centralities, when compared to a reference obtained from proton-induced collisions. The most recent developments on the determination of this normal absorption curve are explained. It is also shown that for sulphur-induced reactions there is full agreement with the extrapolated normal p-A behaviour.

The suppression of ψ' production in heavy ion collisions (Pb-Pb and S-U) is also presented. It is seen to increase with the centrality of the collision and to be significantly stronger than the one measured in proton-induced reactions.

The study of high-energy nucleus-nucleus collisions will be one of the major activities at the future accelerator complex FAIR in Darmstadt. The goal of the research program is the exploration of the QCD phase diagram in the region of high baryon densities.

The main goal of the ALICE Muon spectrometer experiment is the measurement of heavy quark production in p+p, p+A and A+A collisions at LHC energies, via the muonic channel. Physics motivations and expected performances have been presented in this talk.

The 'Compressed Baryonic Matter' (CBM) experiment at the new 'Facility for Antiproton and Ion Research' (FAIR) in Darmstadt is designed to study the properties of highly compressed baryonic matter produced in nucleus-nucleus collisions in the 10 to 45 A GeV energy range. One of the key observables is hidden (J/ψ) and open (D^°, D^±) charm production. To achieve an adequate sensitivity extremely high interaction rates of up to 10⁷events/second are required, resulting in major technological challenges for the detectors, front-end electronics and data processing. The front-end electronics will be self-triggered, autonomously detect particle hits, and output hit parameter together with a precise absolute time-stamp. Several layers of feature extraction and event selection will reduce the primary data flow of about 1 TByte/sec to a level of 1 GByte/sec. This new architecture avoids many limitations of conventional DAQ/Trigger systems and is for example essential for open charm detection, which requires the reconstruction of displaced vertices, in a high-rate heavy ion environment.

Forward muon spectrometer in ALICE in the LHC experiments of CERN will look for signals of quark gluon plasma (QGP) formation in Pb-Pb collisions at 5.6 TeV/nucleon energy. This spectrometer is designed specifically to look for decays of heavy quarkoniums through the correlated muon pairs. The design and construction details with emphasis on the R & D contributions from the nodal agency. Saha Institute of Nuclear Physics (SINP) will be presented.

The CERN-ALICE experiment will produce global data sizes in excess of 75 Mbytes/event, which at event rates of 200–1000 Hz will yield global data streams of 15 Gbyte/s. Online processing–in the form of pattern recognition–is necessary to filter interesting (sub-) events and/or compress data correctly by modelling techniques. A layer of trigger–selecting topologically distinct physics signals (J/ψ) and γ–is currently being developed and benchmarked under stringent conditions. An emphasis is placed on the implementation of this high level trigger (HLT) for muon reconstruction efficiency studies. Investigations thus have alluded to the HLT being able to reduce background by a factor of 4 for low transverse momentum muons and a factor of 100 for high Pt single muons. Furthermore the invocation of the HLT will help refine the resolution of the Pt cut efficiency.

The status of CMS jet simulations and physics analysis in heavy ion collisions is presented. Jet reconstruction and high-pT particle tracking in the high multiplicity environment of heavy ion collisions at the LHC using the CMS calorimetry and tracking system are described. The Monte Carlo tools used to simulate jet quenching are discussed.

The role of dilepton spectroscopy in the exploration of exotic phases of nuclear matter is discussed. Special emphasis is put on the region of moderate beam energies where comparatively long-lived states of compressed matter are created. The opportunities at the future FAIR facility are outlined.

The Transition Radiation Detector (TRD) of ALICE will serve to identify and track electrons in the central region. In this contribution, after a brief introduction of TRD, we review the detector performance concerning electron/pion identification as well as J/ψ and Υ detection.

The Muon Spectrometer of the ALICE experiment is a unique tool to study of the heavy quarks in pp, pA and AA collisions at LHC energies, via the muonic channel. The spectrometer consists of different absorbers, a dipole, five tracking stations and two trigger stations.

The production yield of exotic pentaquarks in high-energy nuclear collisions is estimated on the basis of the standard statistical description of the hadronic freeze-out.

The recently discovered sharp peak in the K⁺/π⁺ ratio in relativistic heavy-ion collisions is discussed in the framework of the thermal model. In this model a rapid change is expected as the hadronic gas undergoes a transition from a baryon-dominated to a mesondominated gas. The transition occurs at a temperature T = 140 MeV and baryon chemical potential μ_B = 410 MeV corresponding to an incident energy of √s_NN = 8.2 GeV.

Longitudinal hadron spectra from Proton-Proton (pp) and nucleus-nucleus (AA) collisions from E_lab = 2 AGeV to √s = 200 AGeV are investigated. The widths of the rapidity spectra for various particle species increases monotonously with energy. The present calculation indicates no sign of a step like behaviour as excepted from the Kaon transverse mass systematics. For Pions, the transport simulation is consistent with a Landau type scaling of the rapidity widths, both in central AA reactions and in pp collisions. However, other hadron species do not follow the Landau scaling. The present model predicts a decreasing rapidity width with particle mass for newly produced particles, not supporting a Landau type flow interpretation.

First order confinement-deconfinement phase transition is studied through hadronic bubble nucleation in an expanding quark-gluon plasma in the context of heavy ion collisions. For this study we consider interacting quark and hadron gas and incorporate the effects of curvature energy. We find that the interactions have the effect of hastening the phase transition whereas the curvature energy has mixed behaviour. Lowering surface tension has the effect of increasing super cooling and slowing down the process of hadronisation in contrast to the case of early Universe. Higher values of bag pressure tend to speed up transition. An interesting feature is the beginning of hadronisation process as soon as the QGP is formed.

The deconfinement phase transition in a rotating compact star and its consequences on neutrino emission have been studied. It has been found that rotating twin star solutions are obtained upto Ω ≈ 4000s⁻¹. For faster rotating stars no twin solution is obtained. The neutrino emission shows a strong directionality.

Parton-parton collisions do not neutralize local color charges in the plasma but they only redistribute them among momentum modes. Color diffusion and conductivity are discussed as processes responsible for the plasma whitening. The conductivity and diffusion coefficients are computed and the time evolution of the color density is studied. The conductivity is shown to be more effective than the diffusion, it whitens the plasma even before the momentum degrees of freedom are thermalized.

I describe the lattice determination of the electrical conductivity of the quark gluon plasma [6]. Since this is the first extraction of a transport coefficient with a degree of control over errors, I next use this to make estimates of other transport related quantities using simple kinetic theory formulæ. The resulting estimates are applied to fluctuations, ultra-soft photon spectra and the viscosity. Dimming of ultra-soft photons is exponential in the mean free path, and hence is a very sensitive probe of transport.

We discuss Taylor expansions of operator expectation values in QCD with respect to chemical potentials of quarks. Maxwell's relations between coefficients and Ward identities between series are used to relate the operators which give the Taylor coefficients of the series for the chiral condensate, the pseudoscalar susceptibility and the mass dependence of quark number susceptibilities. Through such relations the physics of chiral dynamics are explored. The renormalized expectation values of the chiral condensate and its Taylor coefficients are extracted from simulation.

We consider the intersection of N different interfaces interpolating between different Z_N vacua of an SU(N) gauge theory using the Polyakov loop order parameter. Topological arguments show that at such a string-like junction, the order parameter should vanish, implying that the core of this string is in the confining phase. Using the effective potential for the Polyakov loop proposed by Pisarski for QCD, we use numerical minimization technique and estimate the energy per unit length of the core of this string to be about 2.7 GeV/fm at a temperature about twice the critical temperature. For the parameters used, the interface tension is obtained to be about 7 GeV/fm². Lattice simulation of pure gauge theories should be able to investigate properties of these strings. With the interpretation that quark contributions lead to explicit breaking of this Z_N symmetry, such QGPstrings may play important role in the evolution of the quark-gluon plasma phase and in the dynamics of quark-hadron transition.

We calculate the screening potential of a fast parton moving through a quarkgluon plasma in the framework of semi-classical transport theory. We found an anisotropic potential showing a minimum in the direction of the parton velocity. Possible consequences of this potential on binary states in a quark-gluon plasma are discussed.

Jet quenching is considered to be one of the signatures of the formation of quark gluon plasma. In order to investigate the jet quenching, it is necessary to know the properties of jets produced in relativistic heavy ion collisions. In this calculation, we propose that determination of flow parameters may be used to identify and characterize the jets.

We model the evolution of the disoriented chiral condensate formed through both a sudden quench and through a phase transition with a metastable state of arbitrary disorientation. We show that the total multiplicity distributions of charged and neutral pions functions are dramatic characteristic signals for the DCC and are related directly to the way in which the DCC forms.

Within the framework of a polynomial field theory the diquark interaction energies in quark-gluon plasma are explicitly calculated. In particular, two- and three-diquark interaction energies are computed using ϕ⁴–theory and ϕ⁶–terms in the effective Lagrangian and their role in the stability of diquark stars is pointed out.

This paper presents a personal account of the scientific and professional adventures of Bikash Sinha on the occasion of the celebration of his 60'th birth anniversary held at Kolkata in February, 2005.