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Freeze-out in hydrodynamical models in relativistic heavy ion collisions (1999)

Volodymyr K. Magas Csaba Anderlik László Pal Csernai Frederique Grassi Walter Greiner Yogiro Hama Takeshi Kodama Zsolt Iosif Lazar Horst Stöcker

In continuum and fluid dynamical models, particles, which leave the system and reach the detectors, can be taken into account via freeze-out (FO) or final break-up schemes, where the frozen out particles are formed on a 3-dimensional hypersurface in space-time. Such FO descriptions are important ingredients of evaluations of two-particle correlation data, transverse-, longitudinal-, radial- and cylindrical- flow analyses, transverse momentum and transverse mass spectra and many other observables. The FO on a hypersurface is a discontinuity, where the pre FO equilibrated and interacting matter abruptly changes to non-interacting particles, showing an ideal gas type of behavior.

Rho meson broadening and dilepton production in heavy ion collisions (1999)

Song Gao Charles Gale Christoph Ernst Horst Stöcker Walter Greiner

The modification of the width of the rho meson due to in-medium decays and collisions is evaluated. In high temperature and/or high density hadronic matter, the collision width is much larger than the one-loop decay width. The large width of the meson in matter seems to be consistent with some current interpretations of the e+e mass spectra measured at the CERN/SPS.

Plural semantics for natural language understanding : a computational proof-theoretic approach (2005)

Uta Schwertel

The semantics of natural language plurals poses a number of intricate problems – both from a formal and a computational perspective. In this thesis I investigate problems of representing, disambiguating and reasoning with plurals from a computational perspective. The work defines a computationally suitable representation for important plural constructions, proposes a tractable resolution algorithm for semantic plural ambiguities, and integrates an automatic reasoning component for plurals. My solution combines insights from formal semantics, computational linguistics and automated theorem proving and is based on the following main ideas. Whereas many existing approaches to plural semantics work on a model-theoretic basis using higher-order representation languages I propose a proof-theoretic approach to plural semantics based on a flat firstorder semantic representation language thus showing that a trade-off between expressive power and logical tractability can be found. The problem of automatic disambiguation of plurals is tackled by a deliberate decision to drastically reduce recourse to contextual knowledge for disambiguation but rely instead on structurally available and thus computationally manageable information. A further central aspect of the solution lies in carefully drawing the borderline between real ambiguity and mere indeterminacy in the interpretation of plural noun phrases. As a practical result of my computational proof-theoretic approach to plural semantics I can use my methods to perform automated reasoning with plurals by applying advanced firstorder theorem provers and model-generators available off-the shelf. The results are prototypically implemented within the two logic-oriented natural language understanding applications DRoPs and Attempto. DRoPs provides an automatic plural disambiguation component for uncontrolled natural language whereas Attempto works with a constructive disambiguation strategy for controlled natural language. Both systems provide tools for the automated analysis of technical texts allowing users for example to automatically detect inconsistencies, to perform question answering, to check whether a conjecture follows from a text or to find equivalences and redundancies.

Griechische Mythologie (1860)

Ludwig Preller

Die Monikins (1835)

James Fenimore Cooper

Bleakhaus (1855)

Charles Dickens

Früchte aus den sogenannt goldenen Zeiten des achtzehnten Jahrhunderts : (1801 - 1803) (1830)

Johann Gottfried von Herder

Large p(t) enhancement from freeze out (1999)

Volodymyr K. Magas Csaba Anderlik László Pal Csernai Frederique Grassi Walter Greiner Yogiro Hama Takeshi Kodama Zsolt Iosif Lazar Horst Stöcker

Freeze out of particles across three dimensional space-time hypersurface is discussed in a simple kinetic model. The final momentum distribution of emitted particles, for freeze out surfaces with space-like normal, shows a non-exponential transverse momentum spectrum. The slope parameter of the pt distribution increases with increasing pt, in agreement with recently measured SPS pion and h spectra.

Die Insel Felsenburg oder wunderliche Fata einiger Seefahrer : eine Geschichte aus dem Anfange des achtzehnten Jahrhunderts (1828)

Johann Gottfried Schnabel

Neutron star properties in the quark-meson coupling model (1999)

Subrata Pal Matthias Hanauske Ismail A. I. Zakout Horst Stöcker Walter Greiner

The effects of internal quark structure of baryons on the composition and structure of neutron star matter with hyperons are investigated in the quark- meson coupling (QMC) model. The QMC model is based on mean-field description of nonoverlapping spherical bags bound by self-consistent exchange of scalar and vector mesons. The predictions of this model are compared with quantum hadrodynamic (QHD) model calibrated to reproduce identical nuclear matter saturation properties. By employing a density dependent bag constant through direct coupling to the scalar field, the QMC model is found to exhibit identical properties as QHD near saturation density. Furthermore, this modified QMC model provides well-behaved and continuous solutions at high densities relevant to the core of neutron stars. Two additional strange mesons are introduced which couple only to the strange quark in the QMC model and to the hyperons in the QHD model. The constitution and structure of stars with hyperons in the QMC and QHD models reveal interesting di erences. This suggests the importance of quark structure e ects in the baryons at high densities. PACS number(s): 26.60.+c, 21.65.+f, 12.39.Ba, 24.85.+p

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