Question of direct measurement of the quark charge

Feynman has suggested that the average charge of hadrons produced in a particular kinematic region in deep-inelastic lepton scattering reflects the charge of the struck constituent. It is shown that such hadronic tests for the quark charge depend on specific properties of the final-state interaction even when the conditions suggested by Feynman for the validity of these tests are satisfied. Such tests are used here to distinguish among various classes of production models.