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### Topological charge screening and the ‘proton spin’ beyond the chiral limit / Stephan Narison; G. Veneziano; Graham Shore

Nuclear Physics B, Volume: "B546", Issue: 1-2, Pages: 235 - 278

Swansea University Author:

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DOI (Published version): 10.1016/S0550-3213(99)00061-9

Abstract

The theory of the proton spin' effect proposed in our earlier papers is extended to include the chiral SU(3) symmetry breaking and flavour mixing induced by non-vanishing quark masses in QCD. The theoretical basis is the derivation of exact, unified Goldberger-Treiman (GT) relations valid beyo...

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Published in: Nuclear Physics B 05503213 1998 https://cronfa.swan.ac.uk/Record/cronfa31902 No Tags, Be the first to tag this record!
Abstract: The theory of the proton spin' effect proposed in our earlier papers is extended to include the chiral SU(3) symmetry breaking and flavour mixing induced by non-vanishing quark masses in QCD. The theoretical basis is the derivation of exact, unified Goldberger-Treiman (GT) relations valid beyond the chiral limit. The observed suppression in the flavour singlet axial charge $a^0(Q^2)$ is explained by an anomalously small value for the slope of the singlet current correlation function $<0|T~\pl^\m J_{\m 5}^0 ~ \pl^\n J_{\n 5}^0 |0>$, a consequence of the screening of topological charge in the QCD vacuum. Numerical predictions are obtained by evaluating the current correlation functions using QCD spectral sum rules. The results, $a^0(Q^2) = 0.31 \pm 0.02$ and $\int dx ~g_1^p(x,Q^2) = 0.141 \pm 0.005$ (at $Q^2=10 \~\GV^2$), are in good agreement with current experimental data on the polarised proton structure function College of Science 1-2 235 278