We investigate the twist-3 effects in the polarized virtual photon structure.
The structure functions g1γ and g2γ of polarized photon could
be experimentally studied in the future polarized ep or e+e− colliders.
The leading contributions to g1γ are the twist-2 effects, while
another structure function g2γ, which only exists for the virtual
photon target, receives not only the twist-2 but also twist-3 contributions. We
first show that the twist-3 effects actually exist in the box-diagram
contributions and we extract the twist-3 part, which can also be reproduced by
the pure QED operator product expansion. We then calculate the non-trivial
lowest moment (n=3) of the twist-3 contribution to g2γ in QCD. For
large Nc (the number of colors), the QCD analysis of the twist-3 effects in
the flavor nonsinglet part of g2γ becomes tractable and we can obtain
its moments in a compact form for all n.Comment: 27 pages, LaTeX, 9 eps figures, eqsection.sty file included, Appendix
A added, some minor changes for Fig.