Jets in anti pp collisions: Radiation zeroes and the electric charges of colored quarks

Measurements involving more than one photons (e.g., γγ -> hadrons, e+e- -> qanti qγ) can determine the electric charge of colored quarks rather than the color-averaged value measured, for example, by the R-value in e+e- -> hadrons. We draw attention to the fact that this measurement of the absolute quark charges can be performed in hadron collisions via the process qq -> qqγ. The charge signature is dramatic due to the appearance of radiation zeroes whose position depends on the values of the electric charges. This can be exploited to perform such measurements with a detector lacking γ/π0 separation capability. Such experiments also study the interface of color and electromagnetic amplitudes and can further elucidate the QCD origin of jets. (orig.)