Polarization effects in deep inelastic scattering

In all of the previous treatment it has been assumed that the target spin is averaged over. Thus in (15.3.2) and Wqq or (15.4.5) and 

Experiments using polarized electrons on polarized targets had already been carried out at SLAC as early as 1978 (Algard et ai, 1978). Further information has come from the SLAC-Yale group (Baum et ai, 1983) with 

We consider the collision of longitudinally polarized electrons or muons (helicity A = ) with a polarized nucleon described by a covariant spin vector S/j,. 

The essential property of 5 is that if p = E, p) is the four-momentum of the nucleon then 

At high energies we neglect the lepton mass, and in that case the lepton emits the virtual photon without changing its helicity, as explained in Section 1.3. Also, helicity is then the same as chirality. 

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We have enlarged the treatment of deep inelastic lepton-hadron scattering in three directions. Catalyzed by the major discoveries of the European Muon Collaboration there is a more detailed treatment of both polarization effects and of nuclear eflFects. And in anticipation of HERA we discuss interference which will be important for large physics. 

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