Probing the parton densities of polarized photons at a linear e^+e^- collider
arXiv:hep-ph/9907467 · doi:10.1016/S0920-5632(00)00185-7
Abstract
The present theoretical status of spin-dependent parton densities Delta f^γ(x,Q^2) of circularly polarized photons is briefly reviewed. It is then demonstrated that measurements of the deep-inelastic spin asymmetry A_1^γ\simeq g_1^γ/F_1^γ and of di-jet rapidity distributions at a future linear e^+e^- collider appear to be particularly suited for a determination the spin-dependent photonic quark and gluon densities, respectively. Special emphasis is devoted to a comparison of the different sources of polarized photons at a linear collider: the equivalent photon approximation and backscattered laser (Compton) photons. It is shown that backscattered laser photons are highly favorable, even indispensable, for decent measurements of the Delta f^γ(x,Q^2).
7 pages, LaTeX, 4 eps figures, uses amssymb, espcrc2 (included), and epsfig styles; Contribution to the Proceedings of the `International Conference on the Structure and Interactions of the Photon (Photon99)' [Nucl. Phys. B (Proc. Suppl.)], Freiburg, Germany, May 1999