The process e+e--> qanti qγ and the electric charge of coloured quarks

Measurements involving more than one photon may determine the individual charges of colored quarks rather than the color-averaged value measured, for example, by the R-value in e+e- -> hadrons. We investigate the process e+e- -> qanti qγ and find that phi-distributions, where phi is the azimuthal angle of the quark with respect to the γ-momentum, are very sensitive to the charge assignments of colored quarks. We study experimental implications and make comparisons with the process qq -> qqγ, taking place in hadron collision experiments. (orig.)