Strange mesons in dense nuclear matter

Experimental data on the production of kaons and antikaons in heavy ion collisions at relativistic energies are reviewed with respect to in-medium effects. The $K^-/K^+$ ratios measured in nucleus-nucleus collisions are 1 - 2 orders of magnitude larger than in proton-proton collisions. The azimuthal angle distributions of $K^+$ mesons indicate a repulsive kaon-nucleon potential. Microscopic transport calculations consistently explain both the yields and the emission patterns of kaons and antikaons when assuming that their properties are modified in dense nuclear matter. The $K^+$ production excitation functions measured in light and heavy collision systems provide evidence for a soft nuclear equation-of-state.Comment: 16 pages, 12 figures, Invited talk at the 7. international Conference Nucleus-Nucleus Collisions, Strasbourg, July 3-7, 200

Statistical hadronization of charm: from FAIR to the LHC

We discuss the production of charmonium in nuclear collisions within the framework of the statistical hadronization model. We demonstrate that the model reproduces very well the availble data at RHIC. We provide predictions for the LHC energy where, dependently on the charm production cross section, a dramatically different behaviour of charmonium production as a function of centrality might be expected. We extend our predictions for charm production towards the threshold energies, where charm is expected to be measured at the future FAIR facility.Comment: 4 pages, 3 figures; proceedings of QM200

Kaon properties and cross sections in nuclear medium

Results for the $\pi + N \to \Lambda, \Sigma + K$ reactions in nuclear matter of Ref. nucl-th/0004011 are presented. To evaluate the in-medium modification of the reaction amplitude as a function of the baryonic density we introduce relativistic, mean-field potentials for the initial, final and intermediate mesonic and baryonic states in the resonance model. These vector and scalar potentials were calculated using the quark meson coupling model. Contrary to earlier work which has not allowed for the change of the cross section in medium, we find that the data for kaon production at SIS energies are consistent with a repulsive $K^+$-nucleus potential.Comment: 5 pages, 3 postscript figures included, uses iopart.cls and iopart10.clo (included), presented by K.T. at the 5th International Conference on Strangeness in Quark Matter, July 20 - 25, 2000, Berkeley, California, to be published in the proceedings, J. Phys. G. An explanation has been added in Sec. 3 with a new figur

How many phases meet at the chiral critical point?

We explore the phase diagram of NJL-type models near the chiral critical point allowing for phases with spatially inhomogeneous chiral condensates. In the chiral limit it turns out that the region in the mean-field phase diagram where those phases are energetically preferred very generically reaches out to the chiral critical point. The preferred inhomogeneous ground state in this vicinity possibly resembles a lattice of domain wall solitons. This raises the question of their relevance for the phase diagram of QCD.Comment: 7 pages, 1 figure; v2: minor corrections, as published in PR

Model of correlated sequential adsorption of colloidal particles

We present results of a new model of sequential adsorption in which the adsorbing particles are correlated with the particles attached to the substrate. The strength of the correlations is measured by a tunable parameter $\sigma$. The model interpolates between free ballistic adsorption in the limit $\sigma\to\infty$ and a strongly correlated phase, appearing for $\sigma\to0$ and characterized by the emergence of highly ordered structures. The phenomenon is manifested through the analysis of several magnitudes, as the jamming limit and the particle-particle correlation function. The effect of correlations in one dimension manifests in the increased tendency to particle chaining in the substrate. In two dimensions the correlations induce a percolation transition, in which a spanning cluster of connected particles appears at a certain critical value $\sigma_c$. Our study could be applicable to more general situations in which the coupling between correlations and disorder is relevant, as for example, in the presence of strong interparticle interactions.Comment: 6 pages, 8 EPS figures. Phys. Rev. E (in press

Covariant transport approach for strongly interacting partonic systems

The dynamics of partons, hadrons and strings in relativistic nucleus-nucleus collisions is analyzed within the novel Parton-Hadron-String Dynamics (PHSD) transport approach, which is based on a dynamical quasiparticle model for partons (DQPM) matched to reproduce recent lattice-QCD results - including the partonic equation of state - in thermodynamic equilibrium. Scalar- and vector-interaction densities are extracted from the DQPM as well as effective scalar- and vector-mean fields for the partons. The transition from partonic to hadronic degrees of freedom is described by covariant transition rates for the fusion of quark-antiquark pairs or three quarks (antiquarks), respectively, obeying flavor current-conservation, color neutrality as well as energy-momentum conservation. Since the dynamical quarks and antiquarks become very massive close to the phase transition, the formed resonant 'pre-hadronic' color-dipole states ($q\bar{q}$ or $qqq$) are of high invariant mass, too, and sequentially decay to the groundstate meson and baryon octets increasing the total entropy. When applying the PHSD approach to Pb+Pb colllisions at 158 A$\cdot$GeV we find a significant effect of the partonic phase on the production of multi-strange antibaryons due to a slightly enhanced $s{\bar s}$ pair production from massive time-like gluon decay and a larger formation of antibaryons in the hadronization process.Comment: 12 pages, 6 figures, to be published in the Proceedings of the 26th Winter Workshop on `Nuclear Dynamics', Ochto Rios, Jamaica, 2-9 January, 2010

Influence of Hydrodynamic Interactions on the Kinetics of Colloidal Particle's Adsorption

The kinetics of irreversible adsorption of spherical particles onto a flat surface is theoretically studied. Previous models, in which hydrodynamic interactions were disregarded, predicted a power-law behavior $t^{-2/3}$ for the time dependence of the coverage of the surface near saturation. Experiments, however, are in agreement with a power-law behavior of the form $t^{-1/2}$. We outline that, when hydrodynamic interactions are considered, the assymptotic behavior is found to be compatible with the experimental results in a wide region near saturation.Comment: 4 pages, 1 figures, Phys. Rev. Lett. (in press