Octet contributions in radiative upsilon decays

Abstract

We analyze the end-point region of the photon spectrum in semi-inclusive radiative decays of very heavy quarkonium (m alpha_s^2 >> Lambda_QCD). The S- and P-wave octet shape functions are calculated. When they are included in the analysis of the photon spectrum of the Upsilon (1S) system the agreement with data becomes excellent.

Comments: 4 pages, 2 figures, talk given at Quark Confinement and the Hadron Spectrum VI, to appear in the proceedings