574 research outputs found
Quark liberation and coalescence at CERN SPS
The mischievous linear coalescence approach to hadronization of quark matter
is shown to violate strangeness conservation in strong interactions. The
simplest correct quark counting is shown to coincide with the non-linear
algebraic coalescence rehadronization model, ALCOR. The non-linearity of the
ALCOR model is shown to cancel from its simple predictions for the relative
yields of (multi-)strange baryons. We prove, model independently, that quark
degrees of freedom are liberated before hadron formation in 158 AGeV central Pb
+ Pb collisions at CERN SPS.Comment: Latex file, 6 pages, improved text and conclusio
Properties of quark matter produced in heavy ion collision
We describe the hadronization of quark matter assuming that quarks creating
hadrons coalesce from a continuous mass distribution. The pion and antiproton
spectrum as well as the momentum dependence of the antiproton to pion ratio are
calculated. This model reproduces fairly well the experimental data at RHIC
energies.Comment: 9 pages, 6 Postscript figures, typos are correcte
Towards the Equation of State of Classical SU(2) Lattice Gauge Theory
We determine numerically the full complex Lyapunov spectrum of SU(2)
Yang-Mills fields on a 3-dimensional lattice from the classical chaotic
dynamics. The equation of state, S(E), is determined from the Kolmogorov-Sinai
entropy extrapolated to the large size limit.Comment: 12 pages, 8 PS figures, LaTe
Equation of state for distributed mass quark matter
We investigate how the QCD equation of state can be reconstructed by a
continous mass distribution of non-interacting ideal components. We find that
adjusting the mass scale as a function of the temperature leads to results
which are conform to the quasiparticle model, but a temperature independent
distribution also may fit lattice results. The fitted mass distribution tends
to show a mass gap, supporting the physical picture of the quark coalescence in
hadronization.Comment: talk given at SQM2006, 8 pages, submitted to J.Phys.
The dependence of strange hadron multiplicities on the speed of hadronization
Hadron multiplicities are calculated in the ALCOR model for the Pb+Pb
collisions at CERN SPS energy. Considering the newest experimental results, we
display our prediction obtained from the ALCOR model for stable hadrons
including strange baryons and anti-baryons.Comment: 8 pages, LaTeX in IOP style, appeared in the Proceedings of
Strangeness'97 Conference, Santorini, April 14-18 1997, J. of Physics G23
(1997) 194
Evolution of the concept of Quark Matter: the Ianus face of the heavy ion collisions
Since the beginning of the efforts to produce and understand quark matter
large changes developed in the ideas of description of this matter. In the
present paper we summarize some aspects of this development.Comment: Talk given at 18th International Conference on Ultrarelativistic
Nucleus-Nucleus Collisions: Quark Matter 2005 (QM 2005), Budapest, Hungary,
4-9 Aug 2005. 10 pages, 7 figure
Maximum weight cycle packing in directed graphs, with application to kidney exchange programs
Centralized matching programs have been established in several countries to organize kidney exchanges between incompatible patient-donor pairs. At the heart of these programs are algorithms to solve kidney exchange problems, which can be modelled as cycle packing problems in a directed graph, involving cycles of length 2, 3, or even longer. Usually, the goal is to maximize the number of transplants, but sometimes the total benefit is maximized by considering the differences between suitable kidneys. These problems correspond to computing cycle packings of maximum size or maximum weight in directed graphs. Here we prove the APX-completeness of the problem of finding a maximum size exchange involving only 2-cycles and 3-cycles. We also present an approximation algorithm and an exact algorithm for the problem of finding a maximum weight exchange involving cycles of bounded length. The exact algorithm has been used to provide optimal solutions to real kidney exchange problems arising from the National Matching Scheme for Paired Donation run by NHS Blood and Transplant, and we describe practical experience based on this collaboration
Strange hyperon and antihyperon production from quark and string-rope matter
Hyperon and antihyperon production is investigated using two microscopical
models: {\bf (1)} the fast hadronization of quark matter as given by the ALCOR
model; {\bf (2)} string formation and fragmentation as in the HIJING/B model.
We calculate the particle numbers and momentum distributions for Pb+Pb
collisions at CERN SPS energies in order to compare the two models with each
other and with the available experimental data. We show that these two
theoretical approaches give similar yields for the hyperons, but strongly
differ for antihyperons.Comment: 11 pages, Latex, 3 EPS figures, contribution to the Proceedings of
the 4th International Conference on Strangeness in Quark Matter (SQM'98),
Padova, Italy, 20-24 July 199
Zeroth Law compatibility of non-additive thermodynamics
Non-extensive thermodynamics was criticized among others by stating that the
Zeroth Law cannot be satisfied with non-additive composition rules. In this
paper we determine the general functional form of those non-additive
composition rules which are compatible with the Zeroth Law of thermodynamics.
We find that this general form is additive for the formal logarithms of the
original quantities and the familiar relations of thermodynamics apply to
these. Our result offers a possible solution to the longstanding problem about
equilibrium between extensive and non-extensive systems or systems with
different non-extensivity parameters.Comment: 18 pages, 1 figur
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