Bonn 2001 – scientific programme
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T: Teilchenphysik
T 603: QCD 5
T 603.6: Talk
Thursday, March 29, 2001, 11:15–11:30, HS XII
Fermi-Dirac Correlations in Lambda Pairs in Hadronic Z Decays — •Werner Wiedenmann1 and Georg Wolf2 — 1Werner Wiedenmann, CERN-PPE Div., CH-1211 GENF 23 — 2Georg Wolf, Max-Planck-Inst. fuer Physik, Foehringer Ring 6, 80805 Muenchen
Two-particle correlations of ΛΛ and ΛΛ pairs have been studied in multihadronic Z decays recorded with the ALEPH detector at LEP in the years from 1992 to 1995. The correlations were measured as a function of the four-momentum difference Q of the pair. A depletion of events is observed in the region Q < 2 GeV which could arise from the effects of Fermi-Dirac statistics. In addition the spin content of the Λ pair system has been determined. For Q > 2 GeV the fraction of pairs with spin one is consistent with the value of 0.75 expected for a statistical spin mixture, whilst for Q < 2 GeV this fraction is found to be lower. For ΛΛ pairs, where no Fermi-Dirac correlations are expected, the spin one fraction is measured to be consistent with 0.75 over the entire analysed Q range.