ar X iv : h ep - p h / 02 03 19 1 v 2 1 1 M ay 2 00 2 Radiative Decay of Υ into a Scalar Glueball

We study the radiative decay of Υ into a scalar glueball Υ → γGs using QCD factorization. We find that for this process the non-perturbative effects can be factorized into a matrix element well defined in non-relativistic QCD (NRQCD) and the gluon distribution amplitude. The same NRQCD matrix element appears also in leptonic decay of Υ and therefore can be determined from data. In the asymptotic limit the gluon distribution amplitude is known up to a normalization constant. Using a QCD sum-rule calculation for the normalization constant, we obtain Br(Υ → γGs) to be in the range (1 ∼ 2)× 10−3. Combining this result with data, we find that the candidate scalar glueball f0(1500) or f0(1710) can not be a pure glueball. A glueball and quark bound state mixing pattern suggested in the literature is also shown to be in conflict with data. Near future data from CLEO-III can provide crucial information about scalar glueball properties. PACS numbers: 13.25.Gv, 12.39.Mk, 12.38.Bx, 12.38.-t Typeset using REVTEX 1