Prompt dimuons and D meson production in heavy-ion collisions at the SPS

NA60, a follow-up of NA38/50 at the CERN-SPS, is a third generation heavy-ion experiment finally approved in November 2000 for heavy-ion runs in 2002 and 2003. This article will report about the main motivations which lead to this experiment, the main detector concept and the foreseen physics performance

Dileptons and Photons from Coarse-Grained Microscopic Dynamics and Hydrodynamics Compared to Experimental Data

We compute the radiation of dileptons and photons using relativistic hydrodynamics and a coarse-grained version of the microscopic event generator UrQMD, both of which provide a good description of the hadron spectra. The currently most accurate dilepton and photon emission rates from perturbative QCD and from experimentally-based hadronic calculations are used. Comparisons are made to data on central Pb-Pb and Pb-Au collisions taken at the CERN SPS at a beam energy of 158 A GeV. Both hydrodynamics and UrQMD provide very good descriptions of the photon transverse momentum spectrum measured between 1 and 4 GeV, but very slightly underestimate the low mass spectrum of e+e- pairs, even with greatly broadened rho and omega vector mesons.Comment: 4 pages, 10 figures, Quark Matter 2002 proceeding

Baryonic contributions to e+e- yields in a hydrodynamic model of Pb+Au collisions at the SPS

We analyze e+e- yields from matter containing baryons in addition to mesons using a hydrodynamic approach to describe Pb+Au collisions at 158 A GeV/c. We use two distinctly different e+e- production rates to provide contrast. Although the presence of baryons leads to significant enhancement of e+e- emission relative to that from mesons-only matter, the calculated results fall below the data in the range 400 < M/MeV < 600. The calculated results are, however, only 1.3-1.5 standard deviations below the data, which may not be statistically significant.Comment: 4 pages, 4 figures, proceedings of Quark Matter 9

Elektronische und strukturelle Eigenschaften von Plasma-Siliziumnitrid zur Oberflächenpassivierung von siebgedruckten, bifazialen Silizium-Solarzellen

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Antimicrobial susceptibility of periodontopathogenic bacteria

Objectives The aim of this study was to evaluate the resistance profiles of Aggregatibacter (Actinobacillus) actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia/Prevotella nigrescens and to detect possible changes in antibiotic resistance over the time period of 1991-2005. Methods A. actinomycetemcomitans (125 strains), P. gingivalis (152 strains) and P. intermedia/P. nigrescens (326 strains) isolated during the years 1991-2005 were tested for their susceptibility to amoxicillin/clavulanic acid, clindamycin, metronidazole, phenoxymethylpenicillin and tetracycline using the Etest. Results No antibiotic resistance was detected in P. gingivalis, whereas a few isolates of P. intermedia were not susceptible to clindamycin (0.9%), phenoxymethylpenicillin (13.5%) or tetracycline (12.6%). Amoxicillin/clavulanic acid, tetracycline and metronidazole were the most effective antibiotics against A. actinomycetemcomitans with 0%, 0.8% and 20.8% non-susceptible isolates, respectively. However, 88% of the A. actinomycetemcomitans isolates were non-susceptible to phenoxymethylpenicillin and 88% to clindamycin. When strains isolated in the years 1991-94 were compared with those isolated in the years 2001-04, there was no statistically significant difference in the percentage of A. actinomycetemcomitans strains non-susceptible to clindamycin, metronidazole or phenoxymethylpenicillin, or in the percentage of P. intermedia strains non-susceptible to phenoxymethylpenicillin or tetracycline (P > 0.4 each). Conclusions Increasing antibiotic resistances in periodontopathogenic bacteria are not yet a problem in the Northern part of Switzerlan

Hadron Spectrum in a Two-Colour Baryon-Rich Medium

The hadron spectrum of SU(2) lattice gauge theory with two flavours of Wilson quark is studied on an 8^3x16 lattice using all-to-all propagators, with particular emphasis on the dependence on quark chemical potential mu. As mu is increased from zero the diquark states with non-zero baryon number B respond as expected, while states with B=0 remain unaffected until the onset of non-zero baryon density at mu=m_pi/2. Post onset the pi-meson mass increases in accordance with chiral perturbation theory while the rho becomes lighter. In the diquark sector a Goldstone state associated with a superfluid ground state can be identified. A further consequence of superfluidity is an approximate degeneracy between mesons and baryons with the same spacetime and isospin quantum numbers. Finally we find tentative evidence for the binding of states with kaon quantum numbers within the baryonic medium.Comment: 14 pages, 5 figure

Transport analysis of in-medium hadron effects in pA and AA collisions

The production and decay of vector mesons ($\rho, \omega$) in pA and AA reactions is studied with particular emphasis on their in-medium spectral functions. It is explored within transport calculations if hadronic in-medium decays like $\pi^+\pi^-$ or $\pi^0 \gamma$ might provide complementary information to their dilepton ($e^+e^-$) decays. Whereas the $\pi^+ \pi^-$ signal from the $\rho$-meson is found to be strongly distorted by pion rescattering, the $\omega$-meson Dalitz decay to $\pi^0 \gamma$ appears promising even for more heavy nuclei in $\gamma A$ and pA reactions. Furthermore, the influence of nucleon and kaon/antikaon potentials on the $K^\pm$ yields and spectra in pA collisions is calculated and compared to the recent data from the ANKE Collaboration.Comment: 3 pages, LaTeX, 3 postscript figures; contribution to QNP2002, Juelich, June 10-14, 200