Using QCD sum rules, we compute the diagonal meson-baryon couplings, πNN , ηNN , πΞΞ , ηΞΞ , πΣΣ and ηΣΣ , from the baryon-baryon correlation function with a meson: i∫d4xeiq·x〈0TJB(x)J̄ B(0)M(p)〉 . The calculations are performed to leading order in pμ by considering the two separate Dirac structures, iγ5γμpμ and γ5σμνqμpν separately. We first improve the previous sum rule calculations on these Dirac structures for the πNN coupling by including three-particle pion wave functions of twist 4 and then extend the formalism to calculate the other couplings, ηNN , πΞΞ , ηΞΞ , πΣΣ and ηΣΣ . In the SU(3) symmetric limit, we identify the terms responsible for the F/D ratio in the OPE by matching the obtained couplings with their SU(3) relations. Depending on the Dirac structure considered, we find different identifications for the F/D ratio. The couplings including the SU(3) breaking effects are also discussed within our approach.
Bibliographical noteFunding Information:
This work is supported in part by the Grant-in-Aid for JSPS fellow, and the Grant-in-Aid for scientific research (C) (2) 11640261 of the Ministry of Education, Science, Sports and Culture of Japan. The work of H. Kim is also supported by Research Fellowships of the Japan Society for the Promotion of Science. The work of S.H. Lee is supported by the KOSEF grant number 1999-2-111-005-5 and by the BK 21 project of the Korean Ministry of Education.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics