Improved Measurement of the Branching Fraction and Energy Spectrum of eta' from Upsilon(1S) Decays

Abstract

We present an improved measurement of the ${\eta }^{\prime }$ meson energy spectrum in ${\rm Y}(1S)$ decays, using 1.2 fb^{-1} of data taken at the ${\rm Y}(1S)$ center-of-mass energy with the CLEO III detector. We compare our results with models of the ${\eta }^{\prime }$ gluonic form factor that have been suggested to explain the unexpectedly large $B\to {\eta }^{\prime }{X}_s$ rate. Models based on perturbative QCD fail to fit the data for large ${\eta }^{\prime }$ 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.

17 pages postscript,also available through http://www.lns.cornell.edu/public/CLNS/2006/

References in corpus (8)

• Big-Bang nucleosynthesis (Particle Data Group mini-review)
• The Cosmological Parameters 2006
• Construction, Pattern Recognition and Performance of the CLEO III LiF-TEA RICH Detector
• The two-gluon components of the eta and eta' mesons to leading-twist accuracy
• An Analysis of the Inclusive Decay ${\rm Y}(1S)\to {\eta }^{\prime }X$ and Constraints on the ${\eta }^{\prime }$-Meson Distribution Amplitudes
• Inclusive eta' Production from the Upsilon(1S)
• Study of the Charmless Inclusive B -> eta' X Decay
• Study of high momentum eta' production in B -> eta' X_s

Cited by in corpus (1)

• Comparison of Particle Production in Quark and Gluon Fragmentation at sqrt s ~ 10 GeV