Flavor symmetry breaking of the quark condensate and chiral corrections to the Gell-Mann-Oakes-Renner relation

The relation between the chiral quark condensate in QCD sum rules and chiral perturbation theory is clarified with the help of a low-energy theorem for the scalar and pseudoscalar correlation functions. It is found that the quark condensate should be identified with the non-normal-ordered vacuum expectation value of quark-antiquark fields. Utilising results on flavour SU(3) breaking of the quark condensate from QCD sum rules, the unphysical low-energy constant H_2^r in the chiral Lagrangian, as well as next-to-leading order corrections to the Gell-Mann-Oakes-Renner relation are estimated.

Note:

12 pages, discussion of Psi(0) determinations corrected, refs. added

12.38.Aw
11.55.Hx
12.39.Fe
11.30.Hv
quantum chromodynamics
sum rule
effective Lagrangian: chiral
symmetry: SU(3)
flavor: symmetry breaking
quark: condensation

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