Higher-twist effects in QCD, deep inelastic scattering, and the Drell-Yan process

Abstract

Inclusion of specific effects associated with constituent binding in hadronic wave functions is shown to lead to important non-scaling, nonfactorizing 1/Q ² contributions to cross sections for semi-inclusive deep-inelastic scattering, the Drell-Yan process, and other hard scattering reactions. These 1/Q ² higher-twist terms are predicted to be dominant in well defined kinematic regions such as largex and/or largez. The provide angular distributions typical of longitudinally polarized virtual photons andW's, including sin² θ terms in meson induced Drell-Yan processes and ine ⁺ e ⁻→πX, as well as unusual (1−y) terms in deep-inelastic scattering. Calculations are also presented of the quark structure functions of the pionq _π(x, Q ²) and for the quark to pion fragmentation functionD _π(z, Q ²). Predictions are made for the azimuthal angle dependence of the cross sections for$\pi N \to \mu {\text{ }}\bar \mu X$ andlN→l′πX.