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Journal ArticleDOI

Spectral function sum rules and the SU(3) violation of quark condensates in quantum chromodynamics

01 Sep 1986-Journal of Physics G: Nuclear Physics (IOP Publishing)-Vol. 12, Iss: 9, pp 795-804
TL;DR: In this paper, the pseudoscalar densities were used to obtain bounds on the quark vacuum condensate ratio (ss)/(uu) for the U(1) sector.
Abstract: Positivity conditions on the spectral representation of the pseudoscalar densities are used to obtain bounds on the quark vacuum condensate ratio (ss)/(uu). These relate (ss)/(uu) to the topological susceptibility G(0) of the U(1) sector and appear to favour a smaller value for this quantity than is given by the current-algebra result.
Citations
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Journal ArticleDOI
TL;DR: In this article, the SU(3) and SU(2) flavour symmetry violations in the vacuum were studied from the viewpoint of nonperturbative quark mass generation and independently from charge symmetry-breaking considerations.

10 citations

Journal ArticleDOI
TL;DR: Using a QCD estimate on the quark-vacuum condensate ratio (ss)0/(uu)0, the authors showed that the ratio of the meson wavefunction renormalization constants ZK12/Zpi 1/2 may deviate considerably from the SU(3) symmetric value of unity.
Abstract: Using a QCD estimate on the quark-vacuum condensate ratio (ss)0/(uu)0 the authors show, by deriving a sum rule, that the ratio of the meson wavefunction renormalization constants ZK12//Zpi 1/2 may deviate considerably from the SU(3) symmetric value of unity. This in turn raises the value of the pion-nucleon sigma -term from what is normally expected from the conventional GMOR scheme of chiral symmetry breaking.
References
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Journal ArticleDOI
TL;DR: In this paper, a systematic study is made of the non-perturbative effects in quantum chromodynamics, where the basic object is the two-point functions of various currents and the terms of this series are shown to be of two distinct types.

3,874 citations

Journal ArticleDOI
TL;DR: In this paper, the authors construct the generating functional of U(3)×U(3), which allows them to calculate the Green functions up to and including terms of order p4 (at fixed radio m quark p 2 ) in terms of a few coupling constants which chiral symmetry leaves undetermined.

2,883 citations

Journal ArticleDOI
TL;DR: In this article, the dispersion charmonium theory was extended to include power terms due to the nonperturbative effects of QCD, and an estimate for the gluonic vacuum expectation value was derived.

1,902 citations

Journal ArticleDOI
R.J. Crewther1
TL;DR: The conventional theory for the lack of chirality invariance in the presence of topological charge v fails to resolve the U(1) problem: it involves selection rules which forbid chiral changes ± 2 needed to generate the charged-pion decay constant F π. Possible remedies are considered; if they work.

159 citations

Journal ArticleDOI
TL;DR: In this article, the relation between the usual dispersion relation sum rules and the Laplace transform type sum rules in QCD is discussed, and two specific examples corresponding to the ϱ-coupling constant sum rule and the light quark masses sum rules are considered.

143 citations