Eur. Phys. J. C 20, 283-300
DOI: 10.1007/s100520100674

Factorization scheme and parton distributions in the polarized virtual photon target

K. Sasaki^{1, 2} and T. Uematsu<sup>1, 2

1</sup>  Department of Physics, Faculty of Engineering, Yokohama National University, Yokohama 240-8501, Japan
²  Department of Fundamental Sciences, FIHS, Kyoto University, Kyoto 606-8501, Japan

(Received: 24 January 2001 / Published online: 18 May 2001 -© Springer-Verlag / Società Italiana di Fisica 2001)

Abstract
We investigate spin-dependent parton distributions in the polarized virtual photon target in perturbative QCD up to the next-to-leading order (NLO). In the case , where -Q² (-P²) is the mass squared of the probe (target) photon, the parton distributions can be predicted completely up to NLO, but they are factorization-scheme dependent. We analyze the parton distributions in six different factorization schemes and discuss their scheme dependence. We study, in particular, the QCD and QED axial anomaly effects on the first moments of the parton distributions to see the interplay between the axial anomalies and factorization schemes. We also show that the factorization-scheme dependence is characterized by the large-x behaviors of the quark distributions in the virtual photon. The gluon distribution is predicted to be the same up to NLO among the six factorization schemes examined. In particular, the first moment of the gluon distribution is found to be factorization-scheme independent up to NLO.

© Società Italiana di Fisica, Springer-Verlag 2001