Thoughts on opportunities from high-energy nuclear collisions
This document summarizes thoughts on opportunities from high-energy nuclear collisions.
hep-ph↗
arXiv subjects
Marek Gazdzicki
Publications and source records attributed to Marek Gazdzicki.
From p+p to Pb+Pb Collisions: Wounded Nucleon versus Statistical Models
System size dependence of hadron production properties is discussed within the Wounded Nucleon Model and the Statistical Model in the grand canonical, canonical and micro-canonical formulations. Similarities and differences between predictions of the models related to the treatment of conservation laws are exposed. A need for models which would combine a hydrodynamical-like expansion with conservation laws obeyed in individual collisions is stressed.
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Onset of deconfinement in nucleus-nucleus collisions: Review for pedestrians and experts
Evidence for the energy threshold of creating the quark-gluon plasma in nucleus-nucleus collisions, the so-called onset of deconfinement, has been found by the energy scan program of the NA49 experiment at the CERN SPS. In this paper we review the experimental and theoretical status of this phenomenon. First, the basic, qualitative ideas are presented for non-experts. Next, the latest experimental results are compared to a statistical model within which the onset of deconfinement and its signals had been predicted. Finally, alternative interpretations and open questions are discussed.
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Onset of Deconfinement and Critical Point: NA49 and NA61/SHINE at the CERN SPS
This paper is dedicated to the memory of Jozsef Zimanyi one of the founders of the experiment NA49 at the CERN SPS. Firstly, the paper summarizes the main results of NA49 concerning observation of the onset of deconfinement in central Pb+Pb collisions at the low SPS energies. Secondly, it sketches the physics program of NA61 at the CERN SPS, the successor of NA49, which in particular aims to discover the critical point of strongly interacting matter. Finaly, a brief review of the future experimental programs in the CERN SPS energy range is given.
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Onset of Deconfinement in Nucleus-Nucleus Collisions - Past, Present and Future -
In 2007 Mark I. Gorenstein celebrated his 60th birthday. This report is dedicated to Mark and it sketches the results obtained during the past ten years of our collaboration and friendship. They concern search for and study of the onset of deconfinement in high energy nucleus-nucleus collisions.
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Transparency, Mixing and Reflection of Initial Flows in Relativistic Nuclear Collisions
We propose to use the hadron number fluctuations in the limited momentum regions to study the evolution of initial flows in high energy nuclear collisions. In this method by a proper preparation of a collision sample the projectile and target initial flows are marked in fluctuations in the number of colliding nucleons. We discuss three limiting cases of the evolution of flows, transparency, mixing and reflection, and present for them quantitative predictions obtained within several models. Finally, we apply the method to the NA49 results on fluctuations of the negatively charged hadron multiplicity in Pb+Pb interactions at 158A GeV and conclude that the data favor a hydrodynamical model with a significant degree of mixing of the initial flows at the early stage of collisions.
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Onset of Deconfinement and Critical Point - Future Ion Program at the CERN SPS
A new experimental program to study hadron production in collisions of nuclei at the CERN SPS is presented. The program will focus on measurements of fluctuations and long correlations with the aim to identify properties of the onset of deconfinement and search for the critical point of strongly interacting matter.
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Energy dependence of transverse mass spectra of Lambda hyperons produced in p+p and p+pbar interactions. A compilation
The results on transverse mass spectra of Lambda hyperons produced in all inelastic p+p and p+pbar interactions in the energy range sqrts = 3.6-1800 GeV are compiled and analyzed. The energy dependence of the mean transverse mass and the inverse slope parameter of the spectra is presented and discussed. These results should be used as a reference in the study of Lambda hyperon production in nuclear collisions.
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Fluctuations and NA49
A brief history of the study of fluctuations in high energy nuclear collisions at the CERN SPS performed by NA49 is presented. The ideas and the corresponding experimental data on fluctuations are discussed from the point of view of their sensitivity to the onset of deconfinement.
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Study on chemical equilibrium in nucleus-nucleus collisions at relativistic energies
We present a detailed study of chemical freeze-out in nucleus-nucleus collisions at beam energies of 11.6, 30, 40, 80 and 158A GeV. By analyzing hadronic multiplicities within the statistical hadronization approach, we have studied the chemical equilibration of the system as a function of center of mass energy and of the parameters of the source. Additionally, we have tested and compared different versions of the statistical model, with special emphasis on possible explanations of the observed strangeness hadronic phase space under-saturation.
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Energy dependence of transverse mass spectra of kaons produced in p+p and p+pbar interactions.A compilation
The data on m_T spectra of K0S K+ and K- mesons produced in all inelastic p+p and p+pbar interactions in the energy range sqrt(s)NN=4.7-1800GeV are compiled and analyzed. The spectra are parameterized by a single exponential function, dN/(m_T*dm_T)=C exp(-m_T/T), and the inverse slope parameter T is the main object of study. The T parameter is found to be similar for K0S, K+ and K- mesons. It increases monotonically with collision energy from T~30MeV at sqrt(s)NN=4.7GeV to T~220MeV at sqrt(s)NN=1800GeV. The T parameter measured in p+p and p+pbar interactions is significantly lower than the corresponding parameter obtained for central Pb+Pb collisions at all studied energies. Also the shape of the energy dependence of $T$ is different for central Pb+Pb collisions and p+p(pbar) interactions.
hep-ex↗
Energy Scan Program at the Cern SPS and An Observation of the Deconfinement Phase Transition in Nucleus--Nucleus Collisions
The history and the main results of the energy scan program at the CERN SPS are reviewed. Several anomalies in energy dependence of hadron production predicted as signals of deconfinement phase transition are observed and they indicate that the onset of deconfinement is located at about 30 A GeV. For the first time we seem to have clear evidence for the existence of a deconfined state of matter in nature.
hep-ph↗
Power Law in Hadron Production
In high energy p+p(bar) interactions the mean multiplicity and transverse mass spectra of neutral mesons from eta to Upsilon (m = 0.5 - 10 GeV/c^2) and the transverse mass spectra of pions (m_T > 1 GeV/c^2) reveal a remarkable behaviour: they follow, over more than 10 orders of magnitude, the power-law function:The parameters C and P are energy dependent, but similar for all mesons produced at the same collision energy. This scaling resembles that expected in the statistical description of hadron production: the parameter P plays the role of a temperature and the normalisation constant C is analogous to the system volume. The fundamental difference is, however, in the form of the distribution function. In order to reproduce the experimental results and preserve the basic structure of the statistical approach the Boltzmann factor e^(-E/T) appearing in standard statistical mechanics has to be substituted by a power-law factor (E/Lambda)^(-P).
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Comment on `Charged Particle Ratio Fluctuation as a Signal for Quark-Gluon Plasma' and `Fluctuation Probes of Quark Deconfinement'
Charge fluctuations studied on event-by-event basis have been recently suggested to provide a signal of the equilibrium quark-gluon plasma produced in heavy-ion collisions at high energies. It is argued that the fluctuations generated at the early collision stage when the energy is released can fake the signal.
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Highlights of Cern Workshop on Charm Production in A+A Collisions
Models and experimental effort concerning open and hidden charm production in nuclear collisions discussed at Cern Workshop in December 99 are reviewed. The most recent development is also mentioned.
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Comment on ``Comparison of strangeness production between A+A and p+p reactions from 2 to 160 A GeV", by J. C. Dunlop and C. A. Ogilvie
A recent paper on energy dependence of strangeness production in A+A and p+p interactions written by Dunlop and Ogilvie (Phys. ReV. C61 031901(R) (2000) indicates that there is a significant misunderstanding about the concept of strangeness enhancement and its role as a signal of Quark Gluon Plasma creation. In this comment we will try to clarify some essential points.
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Baryon Number Conservation and Statistical Production of Antibaryons
The statistical production of antibaryons is considered within the canonical ensemble formulation. We demonstrate that the antibaryon suppression in small systems due to the exact baryon number conservation is rather different in the baryon-free (B=0) and baryon-rich (B>1) systems. At constant values of temperature and baryon density in the baryon-rich systems the density of the produced antibaryons is only weakly dependent on the size of the system. For realistic hadronization conditions this dependence appears to be close to B/(B+1) which is in agreement with the preliminary data of the NA49 Collaboration for the antiproton/pion ratio in nucleus-nucleus collisions at the CERN SPS energies. However, a consistent picture of antibaryon production within the statistical hadronization model has not yet been achieved. This is because the condition of constant hadronization temperature in the baryon-free systems leads to a contradiction with the data on the antiproton/pion ratio in e+e- interactions.
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Evidence for Statistical Production of J/psi Mesons in Nuclear Collisions at 158--200 A GeV
The hypothesis of statistical production of J/psi mesons at hadronization is formulated and checked against experimental data. It explains in the natural way the observed scaling behavior of the J/psi to pion ratio at the CERN SPS energies. Using the multiplicities of J/psi and eta mesons the hadronization temperature T_H = 175 MeV is found, which agrees with the previous estimates of the temperature parameter based on the analysis of the hadron yield systematics.
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