Azimuthal asymmetry in lepton-proton scattering at high energies

Abstract

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.