# On the chiral anomaly and the Yang–Mills gradient flow

```@article{Luscher2021OnTC,
title={On the chiral anomaly and the Yang–Mills gradient flow},
author={Martin Luscher},
journal={Physics Letters B},
year={2021}
}```
• M. Luscher
• Published 16 September 2021
• Physics
• Physics Letters B
There are currently two singularity-free universal expressions for the topological susceptibility in QCD, one based on the Yang–Mills gradient flow and the other on density-chain correlation functions. While the latter link the susceptibility to the anomalous chiral Ward identities, the gradient flow permits the emergence of the topological sectors in lattice QCD to be understood. Here the two expressions are shown to coincide in the continuum theory, for any number of quark flavours in the…

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