ar X iv : h ep - p h / 97 10 39 2 v 2 2 2 O ct 1 99 7 Renormalons and Higher - Twist Contributions to Structure Functions

ar X iv : h ep - p h / 97 10 39 2 v 1 1 7 O ct 1 99 7 Renormalons and Higher - Twist Contributions to Structure Functions

We review the possibility to use the renormalons emerging in the perturbation series of the twist-2 part of the nonsinglet structure functions F L , F 2 , F 3 , and g 1 to make approximate predictions for the magnitude of the appertaining twist-4 corrections.

ar X iv : h ep - p h / 97 10 39 2 v 3 2 4 N ov 1 99 7 Renormalons and Higher - Twist Contributions to Structure Functions

We review the possibility to use the renormalons emerging in the perturbation series of the twist-2 part of the nonsinglet structure functions F L , F 2 , F 3 , and g 1 to make approximate predictions for the magnitude of the appertaining twist-4 corrections.

ar X iv : h ep - p h / 98 10 52 7 v 1 2 9 O ct 1 99 8 HIGHER - TWIST CONTRIBUTIONS IN EXCLUSIVE PROCESSES

Using the renormalon technique, we estimate higher-twist contributions in deeply virtual Compton scattering and in hard exclusive π 0 leptoproduction.

ar X iv : h ep - p h / 97 10 22 9 v 1 2 O ct 1 99 7 SLAC - PUB - 7663 October 1997 Z ′ INVESTIGATIONS AT FUTURE LEPTON

ar X iv : h ep - p h / 97 11 22 7 v 1 4 N ov 1 99 7 TUM / T 39 - 97 - 28 Hard Exclusive Meson Production and Nonforward Parton Distributions ∗

We present an analysis of twist-2, leading order QCD amplitudes for hard exclusive leptoproduction of mesons in terms of double/nonforward parton distribution functions. After reviewing some general features of nonforward nucleon matrix elements of twist-2 QCD string operators, we propose a phenomenological model for quark and gluon nonforward distribution functions of nucleons. The correspondi...