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Measurement ofR ine + e − annihilation forsqrt s between 7.4 and 9.4 GeV |
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| Authors: | B. Niczyporuk Z. Jakubowski G. Nowak G. Folger B. Lurz U. Volland H. Wegener J. K. Bienlein R. Graumann H. -J. Trost M. Schmitz F. H. Heimlich R. Nernst A. Schwarz U. Strohbusch P. Zschorsch K. W. Chen A. C. König D. J. Schotanus M. Coles A. Engler R. W. Kraemer D. Marlow F. Messing C. Rippich S. Youssef A. Fridman G. Alexander A. Av-Shalom G. Bella J. Grunhaus M. Scheer LENA Collaboration |
| Affiliation: | 1. Institute of Nuclear Physics, Cracow, Poland 2. Physikalisches Institut der Universit?t Erlangen-Nürnberg, D-8520, Erlangen, Federal Republic of Germany 3. Deutsches Elektronen-Synchrotron DESY, D-2000, Hamburg, Federal Republic of Germany 4. I. Institut für Experimentalphysik der Universit?t, Hamburg, D-2000, Hamburg, Federal Republic of Germany 5. Nijmegen, University of Nijmegen and NIKHEF, The Netherland 6. Department of Physics, Carnegie-Mellon University, Pittsburgh, PA, USA 7. DPhPE, Centre d'Etudes Nucléaires de Saclay, F-91190, Gif sur Yvette, France 8. Department of Physics and Astronomy, Tel-Aviv University, Israel 9. Physikalisches Institut der Universit?t Würzburg, D-8700, Würzburg, Federal Republic of Germany |
| Abstract: | The rationR=σ(e + e ?→hadrons)/σ(e + e ?→ µ+ µ?) was measured with the LENA detector at DORIS in a scan between 7.40 and 7.48 GeV and between 8.67 and 9.43 GeV center of mass energies. Corrected for QED radiative effects,R is found to be constant with an average value ofR=3.37 ±0.06stat±0.23syst. No narrow resonances withΓ ee (Γ had/Γ tot)?0.30 keV (95% C.L.) and no steps have been observed. Based on this value ofR, revised values for υ(1S) resonance parameters are presented. |
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