F. Yuan et al., DETERMINATION OF COLOR-OCTET MATRIX-ELEMENTS FROM E(-)PROCESSES AT LOW ENERGIES()E(), Physical review. D. Particles and fields, 56(3), 1997, pp. 1663-1667
We present an analysis of the preliminary experimental data of direct
J/psi production in e(+)e(-) processes at low energies. We find that t
he color-octet contributions are crucially important to the cross sect
ion in this energy region, and their inclusion produces a good descrip
tion of the data. By fitting to the data, we extract the individual va
lues of two color-octet matrix elements: [O-8(psi)(S-1(0))] approximat
e to 1.1. x 10(-2) GeV3; [O-8(psi)(S-1(0))] is poorly determined becau
se it is sensitive to the variation of the choice of m(c), alpha(s) an
d (O-1(psi)(S-3(1))]. However, (O-8(psi)(P-3(0))]/m(c)(2) is quite sta
ble [about (6-9) x 10(-3) GeV3] when the parameters vary in reasonable
ranges. The uncertainties due to a large experimental errors are also
discussed.