POLARIZATION EFFECTS IN HADRON STRUCTURE FUNCTIONS AND IN QUARK AND GLUON FRAGMENTATIONt

The predictions of QCD for the evolution of the quark and gluon structure functions of a polarized proton are discussed. In fact, the parton polarizations increase with energy, for fixed Feynman x. Thus, polarized protons may be useful for the discovery or investigation of new physical phenomena at very high energy, especially i f there are new interactions or particles whose behavior violates one of the natural symmetries of QCD, such as parity. The mean gluon asymmetry grows as ~nQ2, which implies that the orbital angular momentum of the gluons grows similarly. The evolution of the fragmentation of a parton into a hadron is also governed by QCD. For these, we conjecture that the fragmentation of a quark or gluon into a spinning hadron may well show hel ic i ty correlations. The evolution equations then predict an energy evolution similar to the behavior of the structure functions. The spin correlations in fragmentation could be useful in e-e + and e• reactions with polarized electrons and in deeply inelastic neutrino scattering, even i f the hadronic targets are unpolarized. tContribution to the Proceedings of the Workshop on Polarized Beams for the SSC, Ann Arbor, June, 1985. *Supported in part by the U.S. Department of Energy. 0094-243X/86/1450149-553.00 Copyright 1986 American Institute of Physics