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Large pion pole in Z_{S}^{MOM}/Z_{P}^{MOM} from Wilson action data

J. R. Cudell·A. Le Yaouanc·C. Pittori
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Abstract

We show that, contrarily to recent claims, data from the Wilson (unimproved) fermionic action at three different beta values demonstrate the presence of a large Goldstone boson contribution in the quark pseudoscalar vertex, quantitatively close to our previous estimate based on the SW action with c_{SW}=1.769. We show that discretisation errors on Z_{S}^{MOM}/Z_{P}^{MOM} seem to be much smaller than the Goldstone pole contribution over a very large range of momenta. The subtraction of this non perturbative contribution leads to numbers close to one-loop BPT.

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J. R. Cudell, A. Le Yaouanc, C. Pittori. 2001-07-20. Large pion pole in Z_{S}^{MOM}/Z_{P}^{MOM} from Wilson action data. https://doi.org/10.1016/s0370-2693(01)00903-0

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