192 research outputs found
Strange Antibaryons from QGP
We study as function of the collision energy and stopping the thermal
conditions reached in a quark-gluon plasma fireball formed in a relativistic
heavy ion collision. We explore strange particle yields for the current round
of Pb-Pb and Au-Au experiments.Comment: 4 pages, LaTeX, 3 postscript figures, Presented at Quark Matter 1995,
Montere
Hot hadronic matter and strange anti-baryons
We demonstrate that both quark-gluon plasma (QGP) and hadronic gas (HG)
models of the central fireball created in S -> W collisions at 200 GeV A are
possible sources of the recently observed strange (anti-) baryons. From the
theoretical point of view, the HG interpretation we attempt remains more
obscure because of the high fireball temperature required. The thermal
properties of the fireball as determined by the particle ratios, are natural
for the QGP state. We show that the total particle multiplicity emerging from
the central rapidity region allows to distinguish between the two scenarios.Comment: 10 pages, LaTeX, 1 postscript figure
Universal Mass Dependence for Particle Production Rates in , and Collisions from the Quark-Gluon Plasma Perspective
It is demonstrated that universal mass dependence for meson and baryon
inclusive cross-sections advocated recently in annihilation and in
hadronic reactions is consistent also with heavy ion collisions data and can
therefore be used as a reference for quark-gluon plasma studies.Comment: LaTex file, 8 pages, hard copies of 3 (multiple) figures available on
request to [email protected] or [email protected]. PROCSLA.STY file
appended at the end of the LaTeX file for convenienc
Strange Particle Abundance in QGP Formed in 200 GeV A Nuclear Collisions
We investigate here the relative abundance of strange particles produced in
nuclear collisions at the SPS energies (9 GeV A in CM frame) assuming that the
central reaction fireball consists of quark-gluon plasma. We show that the
total strangeness yield in S-S, S-Ag and S-W reactions is compatible with this
picture.Comment: 11 pages, LaTeX, 3 postscript figures, Phys. Lett. B 323 (1994) 39
Strangeness in ultrarelativistic nucleus-nucleus collisions
I discuss strangeness production in nucleus-nucleus reactions at
ultrarelativistic energies (up to 200 AGeV). In these reactions matter may be
created with densities and temperatures in the transition region between
quark-gluon plasma (QGP) and hadron gas. Strange anti-baryon enhancement at 200
AGeV and probably even more so at 10 AGeV signals importance of interactions
beyond hadron gas dynamics. The systematics of strangeness production indicates
that energy and baryon density are key variables while the size of the
production volume plays no visible role. Analysis of strangeness appears useful
to explore thermalization, flow and the post-equilibrium stage in
ultrarelativistic nucleus-nucleus collisions.Comment: 13 pages LaTeX including 6 postscript figures; needs style files
espcrc1,floatfig,epsfig. Invited talk presented at 6th International
Conference on Nucleus-Nucleus Collisions at Gatlinburg, June 2-6, 1997. To be
published in Proceedings in Nuclear Physics
Confronting particle emission scenarios with strangeness data
We show that a hadron gas model with continuous particle emission instead of
freeze out may solve some of the problems (high values of the freeze out
density and specific net charge) that one encounters in the latter case when
studying strange particle ratios such as those by WA85. This underlines the
necessity to understand better particle emission in hydrodynamics to be able to
analyze data. It also re-opens the possibility of a quark-hadron transition
occuring with phase equilibrium instead of explosively.Comment: 13 pages, 2 figures, to appear in Phys. Rev. Let
Strange Particle Freeze-Out
We reconsider thermal conditions of the central fireball presumed to be the
source of abundantly produced strange (anti-)baryons in S -> W collisions at
200 GeV A. We show that it is possible to completely fix the freeze-out
temperature of strange particles in terms of the central rapidity kaon to
Lambda particle abundance ratio at fixed, high transverse mass using a
non-equilibrium hadronization model and the measured quark fugacities.Comment: The reference on front page of the first submission is wrong. 8
pages, LaTeX, 3 postscript figure
QGP Formation and Strange Antibaryons
We analyze current experimental results and explore, as function of the
collision energy and stopping in relativistic nuclear collisions, the
production yields of strange antibaryons, assuming formation of a deconfined
thermal QGP-fireball which undergoes a sudden hadronisation.Comment: Replaced by the published version. 11 pages, 3 figure
Petroleum potential of sedimentary basins in Vietnam: long-term geoscientific co-operation with the Vietnam Petroleum Institute
The Vietnam Petroleum Institute (VPI) and the Geological Survey of Denmark and Greenland (GEUS) have carried out a programme of geoscientific research and institutional capacity building since 1995. It has included geoscientific projects focused on assessment of the hydrocarbon potential of selected sedimentary basins, technology transfer and inhouse training at VPI in Hanoi and at GEUS in Copenhagen. Co-operation is continuing within the framework of a new, long-term project that aims to strengthen research capacity in Vietnam within the fields of basin analysis and modelling
Strangeness Enhancement Scenarios: Fireball or Independent Strings?
Due to the long-standing discrepancy between NA35 and NA36 data on
production, two drastically different scenarios of strangeness enhancement are
still possible. Independent string models, such as the dual parton model, lead
to results close to the NA36 data. On the contrary, the NA35 results can only
be described by introducing full final state rescattering of the produced
particles. The corresponding predictions for central - collisions at
CERN energies differ by a factor 3 to 4. Preliminary data on the net proton
(-) rapidity distribution in - collisions favor the
independent string scenario.Comment: 12 pages, Plain Tex, no figure
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