Bochum 1998 – wissenschaftliches Programm
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HK: Hadronen und Kerne
HK 68: Structure of Baryons, Mesons X, Theory
HK 68.3: Gruppenbericht
Donnerstag, 19. März 1998, 15:00–15:30, J
Hadron Structure from the Operator Product Expansion and Instantons — •Hilmar Forkel1, M.K. Banerjee2, and M. Nielsen3 — 1Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 19, 69120 Heidelberg — 2Department of Physics, University of Maryland, College Park, U.S.A. — 3Instituto de Física, Universidade de São Paulo
We generalize the nonperturbative operator product expansion in QCD to include contributions from small-scale instantons. This enables us to calculate hadronic correlation functions at short and intermediate distances analytically. Instanton contributions are found to be important in the nucleon channel and dominant in the pseudoscalar channel. Hadron properties can be extracted from the calculated correlators by Laplace dispersion relations. As applications, we will discuss the calculation of nucleon properties, the role of instantons in isospin breaking, instanton contributions to the pion-nucleon coupling, and a new QCD sum rule for the electromagnetic pion form factor.