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### U_A(1) problems and gluon topology: Anomalous symmetry in QCD / Graham Shore

Hidden Symmetries and Higgs Phenomena. Proceedings,Zuoz 1998, Pages: 201 - 223

Swansea University Author:

Abstract

Many of the distinctive and subtle features of the dynamics in the UA(1) channel in QCD can be related to gluon topology, more precisely to the topological susceptibility χ(k^2) = i \int d^4x e^ikx⟨0|T Q(x) Q(0)|0⟩, where Q = α_s trGμνG ̃μν is the gluon topological charge density. The link is the UA...

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Published in: Hidden Symmetries and Higgs Phenomena. Proceedings,Zuoz 1998 1998 https://arxiv.org/abs/hep-ph/9812354v1 https://cronfa.swan.ac.uk/Record/cronfa32021 No Tags, Be the first to tag this record!
Abstract: Many of the distinctive and subtle features of the dynamics in the UA(1) channel in QCD can be related to gluon topology, more precisely to the topological susceptibility χ(k^2) = i \int d^4x e^ikx⟨0|T Q(x) Q(0)|0⟩, where Q = α_s trGμνG ̃μν is the gluon topological charge density. The link is the UA(1) axial (ABJ) anomaly. In this lecture, we describe the anomalous UA(1) chiral Ward identities in a functional formalism and show how two apparently unrelated ‘UA(1) problems’ – the mass of the η′ and the violation of the Ellis- Jaffe sum rule in polarised deep-inelastic scattering – can be explained in terms of the gluon topological susceptibility. They are related through a UA(1) extension of the Goldberger- Treiman formula, which is derived here for QCD with both massless and massive quarks. College of Science 201 223