Determination of color-octet matrix elements from e{sup +}e{sup {minus}} processes at low energies
- Department of Physics, Peking University, Beijing 100871, Peoples Republic of (China)
- China Center of Advanced Science and Technology (World Laboratory), Beijing 100080, Peoples Republic of (China)
We present an analysis of the preliminary experimental data of direct J/{psi} production in e{sup +}e{sup {minus}} processes at low energies. We find that the color-octet contributions are crucially important to the cross section in this energy region, and their inclusion produces a good description of the data. By fitting to the data, we extract the individual values of two color-octet matrix elements: {l_angle}O{sub 8}{sup {psi}}({sup 1}S{sub 0}){r_angle}{approx}1.1{times}10{sup {minus}2} GeV{sup 3}; {l_angle}O{sub 8}{sup {psi}}({sup 3}P{sub 0}){r_angle}/m{sub c}{sup 2}{approx}7.4{times}10{sup {minus}3} GeV{sup 3}. We discuss the allowed range of the two matrix elements constrained by the theoretical uncertainties. We find that {l_angle}O{sub 8}{sup {psi}}({sup 1}S{sub 0}){r_angle} is poorly determined because it is sensitive to the variation of the choice of m{sub c}, {alpha}{sub s} and {l_angle}O{sub 1}{sup {psi}}({sup 3}S{sub 1}){r_angle}. However, {l_angle}O{sub 8}{sup {psi}}({sup 3}P{sub 0}){r_angle}/m{sub c}{sup 2} is quite stable [about (6{minus}9){times}10{sup {minus}3} GeV{sup 3}] when the parameters vary in reasonable ranges. The uncertainties due to large experimental errors are also discussed. {copyright} {ital 1997} {ital The American Physical Society}
- OSTI ID:
- 527134
- Journal Information:
- Physical Review, D, Journal Name: Physical Review, D Journal Issue: 3 Vol. 56; ISSN PRVDAQ; ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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