Parton Content of Polarized Photons: Theoretical Status and Experimental Prospects

The theoretical framework for a next-to-leading order QCD analysis of the spin-dependent parton densities ∆f(x,Q) of the longitudinally polarized photon and of its structure function g 1 (x,Q ) is reviewed in some detail. Special emphasis is given to the specific features of different factorization schemes. Two conceivable scenarios for the polarized parton densities ∆f(x,Q) are introduced, which are suitable to study the sensitivity of future experiments to the so far unmeasured ∆f . The experimental prospects of determining ∆f at a polarized collider mode of HERA or at a linear ee collider are outlined. Finally, the Q-evolution of the parton content of linearly polarized photons, which shows some remarkable differences, is briefly discussed. Talk presented at the workshop on ‘Photon Interactions and the Photon Structure’, Lund, Sweden, September 1998. Parton Content of Polarized Photons: Theoretical Status and Experimental Prospects