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The Correlator of Topological Charge Densities at low $Q^2$ in QCD

B. L. Ioffe
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Abstract

The correlator of topological charge densities $χ(Q^2)$ in QCD is calculated in the domain of low $Q^2$. Basing on the Ward identities the low energy theorems are proved. The value of the first derivative $χ^{\prime}(0)$ found recently by QCD sum rules \cite{1} is used. The contributions of pseudoscalar quasi-Goldstone bosons as intermediate states in the correlator are calculated with the account of $η-π$ mixing.

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B. L. Ioffe. 1998-11-02. The Correlator of Topological Charge Densities at low $Q^2$ in QCD. https://arxiv.org/abs/hep-ph/9811217

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