9 research outputs found
Thermal Hadronization and Hawking-Unruh Radiation in QCD
We conjecture that because of color confinement, the physical vacuum forms an
event horizon for quarks and gluons which can be crossed only by quantum
tunneling, i.e., through the QCD counterpart of Hawking radiation by black
holes. Since such radiation cannot transmit information to the outside, it must
be thermal, of a temperature determined by the chromodynamic force at the
confinement surface, and it must maintain color neutrality. We explore the
possibility that the resulting process provides a common mechanism for thermal
hadron production in high energy interactions, from annihilation to
heavy ion collisions.Comment: 29 pages, 14 figure
Inhomogeneous phase of a Gluon Plasma at finite temperature and density
By considering the non-perturbative effects associated with the fundamental
modular region, a new phase of a Gluon Plasma at finite density is proposed. It
corresponds to the transition from glueballs to non-perturbative gluons which
condense at a non vanishing momentum. In this respect the proposed phase is
analogous to the color superconducting LOFF phase for fermionic systems.Comment: 5 pages, 2 figure
Percolation of Color Sources and the determination of the Equation of State of the Quark-Gluon Plasma (QGP) produced in central Au-Au collisions at \sqrt S_{NN}= 200 GeV
The Color String Percolation Model (CSPM) is used to determine the equation
of state (EOS) of the QGP produced in central Au-Au collisions at
= 200 A GeV using STAR data at RHIC. When the initial density
of interacting colored strings exceeds the 2D percolation threshold a cluster
is formed, which defines the onset of color deconfinement. These interactions
also produce fluctuations in the string tension which transforms the Schwinger
particle (gluon) production mechanism into a maximum entropy thermal
distribution. The single string tension is determined by identifying the known
value of the universal hadron limiting temperature = 167.7 2.6
MeV with the CSPM percolation temperature at the critical threshold
=1.2. At mid-rapidity the initial Bjorken energy density and the initial
temperature determine the number of degrees of freedom consistent with the
formation of a 2+1 flavor QGP. An analytic expression for the equation
of state, the sound velocity is obtained in CSPM. The CSPM
and the bulk thermodynamic values and are in excellent agreement in the phase transition region with recent
lattice QCD simulations (LQCD) by the HotQCD Collaboration.Comment: 4 pages, 3 figure
Quasi-particle model for lattice QCD: quark-gluon plasma in heavy ion collisions
We propose a quasi-particle model to describe the lattice QCD equation of
state for pure SU(3) gauge theory in its deconfined state, for .
The method involves mapping the interaction part of the equation of state to an
effective fugacity of otherwise non-interacting quasi-gluons. We find that this
mapping is exact. Using the quasi-gluon distribution function, we determine the
energy density and the modified dispersion relation for the single particle
energy, in which the trace anomaly is manifest. As an application, we first
determine the Debye mass, and then the important transport parameters, {\it
viz}, the shear viscosity, and the shear viscosity to entropy density
ratio, . We find that both and
are sensitive to the interactions, and that the interactions significantly
lower both and .Comment: 10 pages, 8 figures, epj class file, version accepted for publication
in Euro. Phys.J
Charmonium from Statistical Hadronization of Heavy Quarks -- a Probe for Deconfinement in the Quark-Gluon Plasma
We review the statistical hadronization picture for charmonium production in
ultra-relativistic nuclear collisions. Our starting point is a brief reminder
of the status of the thermal model description of hadron production at high
energy. Within this framework an excellent account is achieved of all data for
hadrons built of (u,d,s) valence quarks using temperature, baryo-chemical
potential and volume as thermal parameters. The large charm quark mass brings
in a new (non-thermal) scale which is explicitely taken into account by fixing
the total number of charm quarks produced in the collision. Emphasis is placed
on the description of the physical basis for the resulting statistical
hadronization model. We discuss the evidence for statistical hadronization of
charmonia by analysis of recent data from the SPS and RHIC accelerators.
Furthermore we discuss an extension of this model towards lower beam energies
and develop arguments about the prospects to observe medium modifications of
open and hidden charm hadrons. With the imminent start of the LHC accelerator
at CERN, exciting prospects for charmonium production studies at the very high
energy frontier come into reach. We present arguments that, at such energies,
charmonium production becomes a fingerprint of deconfinement: even if no
charmonia survive in the quark-gluon plasma, statistical hadronization at the
QCD phase boundary of the many tens of charm quarks expected in a single
central Pb-Pb collision could lead to an enhanced, rather than suppressed
production probability when compared to results for nucleon-nucleon reactions
scaled by the number of hard collisions in the Pb-Pb system.Comment: review article, 27 pages, Landoldt review volume "Relativistic Heavy
Ion Physics", Reinhard Stock, edito
A comparative analysis of statistical hadron production
Becattini F, Castorina P, Milov A, Satz H. A comparative analysis of statistical hadron production. EUROPEAN PHYSICAL JOURNAL C. 2010;66(3-4):377-386.We perform a systematic comparison of the statistical model parametrization of hadron abundances observed in high-energy pp, AA and e (+) e (-) collisions. The basic aim of the study is to test if the quality of the description depends on the nature of the collision process. In particular, we want to see if nuclear collisions, with multiple initial interactions, lead to "more thermal" average multiplicities than elementary pp collisions or e (+) e (-) annihilation. Such a comparison is meaningful only if it is based on data for the same or similar hadronic species and if the analyzed data has quantitatively similar errors. When these requirements are maintained, the quality of the statistical model description is found to be the same for the different initial collision configurations
The thermal production of strange and non-strange hadrons in e(+)e(-) collisions
Becattini F, Castorina P, Manninen J, Satz H. The thermal production of strange and non-strange hadrons in e(+)e(-) collisions. EUROPEAN PHYSICAL JOURNAL C. 2008;56(4):493-510.The thermal multihadron production observed in different high energy collisions poses two basic problems. (1) Why do even elementary collisions with comparatively few secondaries (e(+)e(-) annihilation) show thermal behavior? (2) Why is there in such interactions a suppression of strange particle production? We show that the recently proposed mechanism of thermal hadron production through Hawking-Unruh radiation can naturally account for both. The event horizon of color confinement leads to thermal behavior, but the resulting temperature depends on the strange quark content of the produced hadrons, causing a deviation from full equilibrium and hence a suppression of strange particle production. We apply the resulting formalism to multihadron production in e(+)e(-) annihilation over a wide energy range and make a comprehensive analysis of the data in the conventional statistical hadronization model and the modified Hawking-Unruh formulation. We show that this formulation provides a very good description of the measured hadronic abundances, fully determined in terms of the string tension and the bare strange quark mass; it contains no adjustable parameters