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Abstract:We have developed an event mixing technique to observe Bose-Einstein correlations (BEC) between two identical neutral pions produced in photo-induced reactions in the non-perturbative QCD energy region. It is found that the missing-mass consistency cut and the pion-energy cut are essential for the event mixing method to effectively extract BEC observables. A Monte Carlo (MC) simulation is used to validate these constraints and confirms the efficiency of this method. Our work paves the way for similar BEC studies at lower energies where the multiplicity of emitted bosons is limited.

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We present an improved measurement of the η ′ meson energy spectrum in Υ(1S) decays, using 1.2 fb −1 of data taken at the Υ(1S) center-of-mass energy with the CLEO III detector. We compare our results with models of the η ′ gluonic form factor that have been suggested to explain the unexpectedly large B → η ′ X s rate. Models based on perturbative QCD fail to fit the data for large η ′ energies, and thus an explanation outside the realm of the Standard Model or an improved understanding of non-perturbative QCD effects may be needed to account for this large rate.

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