The Pion-Nucleon Coupling Constant in QCD Sum Rules

Abstract

The pion-nucleon coupling constant $g_{πN}$ is studied on the basis of the QCD sum rules. Both the Borel sum rules and the finite energy sum rules for $g_{πN}$ are used to examine the effects of higher dimensional operators (up to dim. 7) and $α_s$ corrections in the operator product expansion. Agreement with the experimental number is reached only when $S_π/S_N$ is greater than one, where $S_π$ ($S_N$) is the continuum threshold for the $g_{πN}$ (nucleon) sum rule.