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