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Bose-Einstein Correlations of Three Charged Pions in Hadronic Z0 Decays

The OPAL Collaboration, K. Ackerstaff et al

hep-exarXiv:hep-ex/9806036

Abstract

Bose-Einstein Correlations (BEC) of three identical charged pions were studied in 4 x 106 hadronic Z0 decays recorded with the OPAL detector at LEP. The genuine three-pion correlations, corrected for the Coulomb effect, were separated from the known two-pion correlations by a new subtraction procedure. A significant genuine three-pion BEC enhancement near threshold was observed having an emitter source radius of r3 = 0.580 +/- 0.004 (stat.) +/- 0.029 (syst.) fm and a strength of λ3 = 0.504 +/- 0.010 (stat.) +/- 0.041 (syst.). The Coulomb correction was found to increase the λ3 value by \~9% and to reduce r3 by ~6%. The measured λ3 corresponds to a value of 0.707 +/- 0.014 (stat.) +/- 0.078 (syst.) when one takes into account the three-pion sample purity. A relation between the two-pion and the three-pion source parameters is discussed.

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