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How precisely can we determine the pion-nucleon coupling constant from the isovector GMO sum rule?

B. Loiseau·T. E. O. Ericson·A. W. Thomas
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Abstract

The isovector GMO sum rule for zero energy forward pion-nucleon scattering is critically studied to obtain the charged pion-nucleon coupling constant using the precise negatively charged pion-proton and pion-deuteron scattering lengths deduced recently from pionic atom experiments. This direct determination leads to a pseudoscalar charged pion-nucleon coupling constant of 14.23 +- 0.09 (statistic) +- 0.17 (systematic). We obtain also accurate values for the pion-nucleon scattering lengths.

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B. Loiseau, T. E. O. Ericson, A. W. Thomas. 2000-02-04. How precisely can we determine the pion-nucleon coupling constant from the isovector GMO sum rule?. https://arxiv.org/abs/hep-ph/0002056

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