Although the pion has spin zero, one-pion exchange depends on nucleon spin and isospin and includes a nuclear tensor force. Shorter-range and multiple-nucleon interactions also matter. The scalar Yukawa potential isolates a range mechanism rather than specifying the complete nuclear force.[ref]
Modern Theory of Nuclear Forces by Evgeny Epelbaum and others. Modern Theory of Nuclear Forces, inspected preprint sections I.B and II.B, especially equation (2.11) and Fig. 12
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