242 research outputs found
Non-equilibrium Hadrochemistry in QGP Hadronization
This survey offers an introductory tutorial for students of any age of the
currently thriving field of hadrochemistry. We discuss the different chemical
potentials, how the hadronic phase space is described and how one evaluates the
abundance of hadrons at time of hadronization. We show that a rather accurate
description of experimental data arises and we present results of fits to
hadron yields at SPS and RHIC. We show that introduction of chemical
non-equilibrium originating in a sudden hadronization of a QGP is favored
strongly at SPS and is presently also emerging at RHIC. The low chemical
freeze-out temperatures are consistent with the picture of single freeze-out
scenario (chemical and thermal freeze-out coincide).Comment: To appear in the proceedings of Pan American Advanced Studies
Institute on New States of Matter in Hadronic Interactions (PASI 2002),
Campos do Jordao, Brazil, 7-18 Jan 2002; American Institute of Physics 2002
*v2 Contains UPDATED RHIC-130 chemical freeze-out analysis
Strangeness and Statistical QCD
We discuss properties of statistical QCD relevant in Fermi phase space model
analysis of strange hadron production experimental data. We argue that the
analysis results interpreted using established statistical QCD properties are
demonstrating formation of the color deconfined state of matter in relativistic
heavy ion collisions at highest CERN-SPS energies and at BNL-RHIC, comprising
deconfined matter composed of nearly massless quarks and gluons, in statistical
equilibrium.Comment: 22 pages, including 7 figures, 3 tables, to appear in Nuclear Physics
Proceedings Supplement: STATISTICAL QCD, held at Bielefeld August 200
Strangeness and thresholds of phase changes in relativistic heavy ion collisions
We discuss how the dynamics of the evolving hot fireball of quark--gluon
matter impacts phase transition between the deconfined and confined state of
matter. The rapid expansion of the fireball of deconfined matter created in
heavy ion collisions facilitates formation of an over-saturated strange quark
phase space. The related excess abundance of strangeness is compensating the
suppression of this semi-heavy quark yield by its quark mass. In addition, the
dynamical expansion of colored quanta pushes against the vacuum structure, with
a resulting supercooling of the transition temperature. We address the status
of the search for the phase boundary as function of reaction energy and
collision centrality and show evidence for a change in reaction mechanism at
sufficiently low energies. The phase diagram derived from the study of hadron
production conditions shows two boundaries, one corresponding to the expected
transition between confined and deconfined matter, with a downward temperature
shift, and the other a high quark density hadronization which appears to
involve heavy effective quarks, at relatively large temperatures.Comment: 10 Pages, presented at Workshop on Light-Cone QCD and Nonperturbative
Hadron Physics 2005 (LC2005), Cairns, July 2005, to appear in proceeding
Probing Dense Matter with Strange Hadrons
Analysis of hadron production experimental data allows to understand the
properties of the dense matter fireball produced in relativistic heavy ion
collisions. We interpret the analysis results and argue that color deconfined
state has been formed at highest CERN-SPS energies and at BNL-RHIC.Comment: 12 pages incl 1 figure, 3 table
- …