Chueng-Ryong Ji, W. Melnitchouk, A. W. Thomas
In a recent Letter, Alberg and Miller presented a calculation of the pion contributions to the self-energy of the nucleon computed from a pseudoscalar (PS) pion-nucleon interaction, with the claim that the result would be equivalent to that with the pseudovector (PV) form. We demonstrate that the PV and PS pion-nucleon couplings do in fact lead to different results for the self-energy. In particular, for the model-independent, leading nonanalytic behavior of the self-energy, the PV theory yields the well-known m_\pi^3 dependence in the chiral limit, while the PS interaction involves an additional, lower-order term ~ m_\pi^2 log(m_\pi^2).
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http://arxiv.org/abs/1206.3671
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