Jiro Kodaira

QCD higher-order effects in polarized electroproduction: Flavour singlet coefficient functions

the QCD corrections of order g−2 to the coefficient functions in polarized electroproduction are calculated for the flavour singlet part. The full g−2 corrections to the sum rule corresponding to the first moment of the structure functions are also discussed. In the singlet case there appears the Adler-Bell-Jackiw anomaly which forces the relevant anomalous dimension to be non-zero. Thus the form of the corrections in the singlet part is different from that in the non-singlet part. Their magnitude turns out to depend on the number of flavours.

QCD higher order effects in spin-dependent deep inelastic electroproduction

QCD effects beyond the leading logarithmic approximation are considered for polarized deep inelastic electroproduction. The corrections of the order g2 to the coefficient functions in the Wilson expansion are calculated by evaluating the Green function for the current product as well as those for the composite operators. We shall clarify how to normalize the composite operators and discuss the renormalization-scheme dependence. It is pointed out that the Q2 dependence is different between the massless and massive quark models.

How can we properly define the Q2 dependent parton distribution function in QCD

Abstract We discuss how we can properly define the Q 2 dependent parton distribution functions in quantum chromodynamics within the framework of the operator product expansion and renormalization group techniques. It is proposed that the moments of the parton distribution functions at Q 2 should be defined as the hadronic expectation values of the twist-2 operators renormalized at Q 2 . The integro-differential equations for the parton densities obtained by Altarelli and Parisi are reproduced in the leading logarithmic approximation. An application of our present formalism will be given in the case of a longitudinal structure function.