We consider the azimuthal angular dependence of the distribution of final-state hadrons in high-energy lepton-proton scattering. The distribution displays an azimuthal asymmetry due to both perturbative and nonperturbative effects. At the large momentum transfers attainable, for example, at the DESY $\mathrm{ep}$ collider HERA we expect the perturbative effects to dominate and constitute a clear test of QCD.

• Received 15 July 1991

DOI:https://doi.org/10.1103/PhysRevD.45.46