Publisher’s Note: Improved measurement of the branching fraction and energy spectrum ofη′fromΥ(1S)decays [Phys. Rev. D74, 092006 (2006)]

Abstract

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.