The interference structure function xG3(x) has been measured for the first time scattering positive and negative muons of opposite helicity off a carbon target. The x dependence observed for Q2 between 40 and 180 (GeV/c2) is in good agreement with predictions of the quark-parton model. The measured ratio 2(auQu + adQd)/(Qu2 + Qd2 = 1.87 ± 0.25 (stat.) ± 0.24 (syst.) is consistent with the hypothesis of fractional quark charges and determines the sign of Qu - Qd to be positive.
ASJC Scopus subject areas
- Nuclear and High Energy Physics