We discuss the possible metastability of the cosmic-ray Centauro quark-matter fireball in terms of the equalization of the quark–gluon and vacuum pressures and the radius of the fireball, as deduced ...from the calculated thermodynamic quantities. We obtain the bag-stability curves as a function of
T,
μ
q
and the bag radius
R and we find that the Centauro fireball is situated within one standard deviation from these curves. This fact, together with the very high baryon density and binding energy and the low entropy per baryon of the state, prompt us to conjecture that the Centauro fireball may possibly be a metastable state.
CASTOR is a novel tungsten/quartz EM and HAD calorimeter, specially designed for the study of “long-penetrating hadrons”, observed in hadron-rich Cosmic-Ray events and suggested to be Strangelets. ...Strangelets are proposed to be formed in the baryon-rich, very forward fragmentation region, through the creation of deconfined quark matter in ultra-relativistic A + A collisions at the LHC. Such objects, if they exist, should be detected and identified in the
10.3
λ
I
calorimeter by their azimuthal asymmetry in energy deposition and their large magnitude of fluctuations in the transition curves, as compared to normal events. We briefly present the calorimeter and discuss the MC simulations for the identification of Strangelets.
We consider the production of strange particles in relativistic nucleus-nucleus collisions. We employ a quark-gluon plasma (QGP) formalism, incorporating the production of the (anti)quarks in the ...plasma during equilibration by the gluon field. We assume generally accepted ital T(musub ital q=0) and musub ital q(ital T=0) values to construct a phase curve, defining an approximate lower limit of the ideal QGP phase. We express the strange particle ratios as function of musub ital q and ital T along this curve and predict quantitatively their minimum QGP values. We analyze the NA36 and WA85 CERN experiments and obtain the quarkchemical potentials, musub ital q, musub ital s and the chemical equilibration, gammasub ital s. The gluon sector, providing the bar q's, is necessary for the correct and consistent estimation of these quantities and prediction of all strange particle ratios. We put forward that the values of ital T, musub ital q, musub ital s, and gammasub ital s are the only significant quantities determining a possible phase transition, not the magnitude of any strange particle ratio, as previously proclaimed. We find that the 200 GeV/nucleon sup 32S-induced interactions at midrapidity may have approached the ideal QGP phase to within about 60%.
Multiplicity fluctuations of positively, negatively, and all charged hadrons in the forward hemisphere were studied in central Pb+Pb collisions at 20A,30A,40A,80A, and 158A GeV. The multiplicity ...distributions and their scaled variances {omega} are presented as functions of their dependence on collision energy as well as on rapidity and transverse momentum. The distributions have bell-like shapes and their scaled variances are in the range from 0.8 to 1.2 without any significant structure in their energy dependence. No indication of the critical point in fluctuations are observed. The string-hadronic ultrarelativistic quantum molecular dynamics (UrQMD) model significantly overpredicts the mean, but it approximately reproduces the scaled variance of the multiplicity distributions. The predictions of the statistical hadron-resonance gas model obtained within the grand-canonical and canonical ensembles disagree with the measured scaled variances. The narrower than Poissonian multiplicity fluctuations measured in numerous cases may be explained by the impact of conservation laws on fluctuations in relativistic systems.
J.Phys.G29:243-262,2003 We consider the change of the strange-quark chemical potential in the phase
diagram of nuclear matter, employing the Wilson loop and scalar quark
condensate order parameters, ...mass-scaled partition functions and enforcing
flavor conservation. Assuming the region beyond the hadronic phase to be
described by massive, correlated and interacting quarks, in the spirit of
lattice and effective QCD calculations, we find the strange-quark chemical
potential to change sign: from positive in the hadronic phase - to zero upon
deconfinement - to negative in the partonic domain. We propose this change in
the sign of the strange-quark chemical potential to be an experimentally
accessible order parameter and a unique, concise and well-defined indication of
the quark-deconfinement phase transition in nuclear matter.
We consider the variation of the strange quark-chemical potential in the
phase diagramme of nuclear matter, employing the order parameters and
mass-scaled partition functions in each domain and ...enforcing flavour
conservation. Assuming the region beyond the hadronic phase to be described by
massive, correlated and interacting quarks, in the spirit of NJL and lattice
calculations, we find the strange quark-chemical potential to attain large
negative values in this domain. We propose that this change in the sign of the
strange quark-chemical potential from positive in the hadronic phase to
negative in the partonic, to be a unique, concise and well-defined indication
of the quark deconfinement phase transition in nuclear matter. We propose also
that, for a chemically equilibrated state in the deconfined region, which
follows an isentropic expansion to hadronization via a second order phase
transition, the fugacities of the equilibrated quark flavours, once fixed in
the primordial state, remain constant throughout the hadronization process.
We have studied the variation of a thermodynamic quantity, the strange
chemical potential, in the phase diagram of nuclear matter, by employing the
partition function in each domain and enforcing ...strangeness conservation. We
propose that the change in the sign of the strange quark chemical potential,
from positive in the hadronic phase to negative in the deconfined quark-gluon
phase, to be a new, unique, concise and well-defined indication of the
quark-deconfinement phase transition in nuclear matter. This signature is
independent of model parameters and interaction mechanisms. We propose also
that, for a state in the deconfined region following an isentropic path to
hadronization via a second order phase trasition, the fugacities of the
equilibrated quark flavours, once fixed in the primordial state, remain
constant throughout the hadronization process. This would enable the knowledge
of the thermodynamic quantities of states situated beyond the hadronic phase.
Data from nucleu-nucleus interactions at AGS and SPS give support to our
proposals.
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