Pion nucleon coupling constant, Goldberger-Treiman discrepancy and $πN$ $σ$ term
We start by studying the Goldberger-Treiman discrepancy (GTd) $Δ= (2.259\pm 0.591)%$. Then we look at the $πN$ $σ$ term, with the dimensionless ratio $σ_N/2m_N=3.35%$. Finally we return to predicting (via the quark model) the $πN$ coupling constant, with GTd $Δ\to 0$ as $m_q\to m_N/3$.
hep-ph↗