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We present an analysis of the preliminary experimental data of direct j/psiproduction in e^e- process at low energies. We find that the color-octetcontributions are crucially important to the cross section at this energyregion, and their inclusion produces a good description of the data. By fittingto the data, we extract the individual values of two color-octet matrixelements: <{\cal O}_8^{\psi}(^1S_0)> \approx 1.1\times 10^{-2} GeV^3, <{\calO}_8^{\psi}(^3P_0)> m_c^2\approx 7.4\times 10^{-3}GeV^3. We discuss the allowedrange of the two matrix elements constrained by the theoretical uncertainties.We find that <{\cal O}_8^{\psi}(^1S_0)> is poorly determined because it issensitive to the variation of the choice of m_c, \alpha_s and <{\calO}_1^{\psi}(^3S_1)>. However <{\cal O}_8^{\psi}(^3P_0)> m_c^2 is quite stable(about (6-9)\times 10^{-3}GeV^3) when the parameters vary in reasonable ranges.The uncertainties due to large experimental errors are also discussed.Comment: 13 page, RevTex, 2 figures in postscript. To appear in Phys. Rev.

physical review. d. particles, fields, gravitation, and cosmology/physical review. d. particles and fields

Determination of color-octet matrix elements from<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow><mml:mrow><mml:msup><mml:mrow><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mi>−</mml:mi></mml:mrow></mml:msup></mml:mrow></mml:math>processes at low energies

Determination of color-octet matrix elements frome+e−processes at low energies