390 research outputs found
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
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.
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
Variational Approach to Real-Time Evolution of Yang-Mills Gauge Fields on a Lattice
Applying a variational method to a Gaussian wave ansatz, we have derived a
set of semi-classical evolution equations for SU(2) lattice gauge fields, which
take the classical form in the limit of a vanishing width of the Gaussian wave
packet. These equations are used to study the quantum effects on the classical
evolutions of the lattice gauge fields.Comment: LaTeX, 12 pages, 5 figures contained in a separate uuencoded file,
DUKE-TH-93-4
Geometric approach to chaos in the classical dynamics of abelian lattice gauge theory
A Riemannian geometrization of dynamics is used to study chaoticity in the
classical Hamiltonian dynamics of a U(1) lattice gauge theory. This approach
allows one to obtain analytical estimates of the largest Lyapunov exponent in
terms of time averages of geometric quantities. These estimates are compared
with the results of numerical simulations, and turn out to be very close to the
values extrapolated for very large lattice sizes even when the geometric
quantities are computed using small lattices. The scaling of the Lyapunov
exponent with the energy density is found to be well described by a quadratic
power law.Comment: REVTeX, 9 pages, 4 PostScript figures include
Chaos Driven by Soft-Hard Mode Coupling in Thermal Yang-Mills Theory
We argue on a basis of a simple few mode model of SU(2) Yang-Mills theory
that the color off-diagonal coupling of the soft plasmon to hard thermal
excitations of the gauge field drives the collective plasma oscillations into
chaotic motion despite the presence of the plasmon mass.Comment: 10 pages, REVTeX, revised manuscript, new titl
Matching Dynamics with Constraints
We study uncoordinated matching markets with additional local constraints
that capture, e.g., restricted information, visibility, or externalities in
markets. Each agent is a node in a fixed matching network and strives to be
matched to another agent. Each agent has a complete preference list over all
other agents it can be matched with. However, depending on the constraints and
the current state of the game, not all possible partners are available for
matching at all times. For correlated preferences, we propose and study a
general class of hedonic coalition formation games that we call coalition
formation games with constraints. This class includes and extends many recently
studied variants of stable matching, such as locally stable matching, socially
stable matching, or friendship matching. Perhaps surprisingly, we show that all
these variants are encompassed in a class of "consistent" instances that always
allow a polynomial improvement sequence to a stable state. In addition, we show
that for consistent instances there always exists a polynomial sequence to
every reachable state. Our characterization is tight in the sense that we
provide exponential lower bounds when each of the requirements for consistency
is violated. We also analyze matching with uncorrelated preferences, where we
obtain a larger variety of results. While socially stable matching always
allows a polynomial sequence to a stable state, for other classes different
additional assumptions are sufficient to guarantee the same results. For the
problem of reaching a given stable state, we show NP-hardness in almost all
considered classes of matching games.Comment: Conference Version in WINE 201
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