Quark and gluon condensates in hadrons and in quark interactions and the role of the quark-antiquark pair in the structure of nuclei

Abstract

Some methods of the perturbative and non-perturbative QCD are reviewed. The QCD sum rules are presented on the example of the p-meson; and the extension of the QCD sum rules from mesons to baryons, and to the meson-baryon coupling constant are given. There are proposed some modifications of the short distance interactions; and the role of the quark-antiquark pair in the structure of nuclei is discussed in some detail.

We introduce the perturbative and the non-perturbative QCD methods, and write the operator product expansion near the light cone. On the example of the p-meson we show the technique of Shifman-Vainstein-Zakharov, and the extension of the QCD sum rules from the meson to the baryon sector, and to the evaluation of the meson-baryon coupling constant. We use the numerical results of Ioffe~and Reinders, Rubinstein and Yazaki.

Using the basic idea of Shifman, Vainstein and Zakharov, we propose a suggestion how to enrich the short distance quark interactions by the explicit inclusion of the quark and gluon condensates. We also consider possible dynamical improvements of the standard QCD sum rules. For that we show the Brodsky-Lepage evolution equation method as a mean of coping with the QCD dynamics in the reduced degrees of freedom. We note a particular 3-quark irreducible force, and reviewing some work of Frankfurt and Strikman we show, how the mark-antiquark pair influences the structure of : nucleon, deuteron, and iron. This force is a “core” of the two-nucleon correlation in nuclei, and accounts for the cumulative effect in the semi-inclusive processes.