coupling determined beyond the chiral limit
Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
Received: 8 July 1999 / Revised version: 20 August 1999 Communicated by W. Weise
Within the conventional QCD sum rules, we calculate the coupling constant, , beyond the chiral limit using two-point correlation function with a pion. For this purpose, we consider the Dirac structure, , at order in the expansion of the correlator in terms of the pion momentum. For a consistent treatment of the sum rule, we include the linear terms in quark mass as they constitute the same chiral order as . In this sum rule, we obtain , which is very close to the empirical coupling. This demonstrates that going beyond the chiral limit is crucial in determining the coupling.
13.75.Gx Pion-baryon interactions - 12.38.Lg Other nonperturbative calculations - 11.55.Hx Sum rules
Copyright Società Italiana di Fisica, Springer-Verlag 2000