Angular dependence of Bose-Einstein correlations in interactions of π+ andK + mesons with protons and nuclei at 250 GeV/c

The angular dependence of Bose-Einstein correlations is studied in interactions of ⁺ andK ⁺ mesons with protons and nuclei at 250 GeV/c. The pion source is found to be elongated along the interaction axis in the c.m.s., with the ratioa between transverse and longitudinal dimension equal to 0.55±0.06 for the case of proton, 0.53±0.13 for the case ofAl and 0.33±0.21 for the case ofAu target. For meson-proton interactions, indication for an increase of the elongation is found with increasing event multiplicity, pair momentum and particle transverse momentum.Now at UIA, Wilrijk, Belgium     

Dominating Functions and Graphs

A graph is called dominating if its vertices can be labelledwith integers in such a way that for every function : thegraph contains a ray whose sequence of labels eventually exceeds. We obtain a characterization of these graphs by producinga small family of dominating graphs with the property that everydominating graph must contain some member of the family.     

Measurement of γp→K + Λ and γp→K + Σ 0 at photon energies up to 1.47 GeV

The reactions pK ⁺ and pK ^{+ 0} have been measured with the multiparticle detector system SAPHIR at ELSA in Bonn. Besides the differential cross sections the polarization and, for the first time, the ⁰ polarization have been determined in a photon induced reaction. All data are presented as functions of the photon energy (from threshold up to 1.47 GeV) and of the kaon production angle (0°–180°). The polarization of both and ⁰ is substantial at all energies and varies strongly with the production angle.This work is supported by the Bundesminister für Forschung und Technologie (BMFT), FK 06 BN 621 I     

Time-asymptotic boson states from infinite mean field quantum systems coupled to the boson gas

By means of cocycle techniques in a recent paper, the global dynamics of mean field-boson couplings has been studied. Here, by restricting to the bosonic system the infinite time limit (t ) for very general initial states, one obtains time-asymptotic states on the bosonicC ^*-Weyl algebra, in which one partially rediscovers the collective ordering of the infinite mean field lattice.