Two-pion exchange potential and the $\pi N$ amplitude

Abstract

We discuss the two-pion exchange potential which emerges from a box diagram with one nucleon (the spectator) restricted to its mass shell, and the other nucleon line replaced by a subtracted, covariant $\pi N$ scattering amplitude which includes $\Delta$, Roper, and $D_{13}$ isobars, as well as contact terms and off-shell (non-pole) dressed nucleon terms. The $\pi N$ amplitude satisfies chiral symmetry constraints and fits $\pi N$ data below $\sim$ 700 MeV pion energy. We find that this TPE potential can be well approximated by the exchange of an effective sigma and delta meson, with parameters close to the ones used in one-boson-exchange models that fit $NN$ data below the pion production threshold.

9 pages (RevTex) and 7 postscript figures, in one uuencoded gzipped tar file

Cited by in corpus (7)

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• High-precision covariant one-boson-exchange potentials for np scattering below 350 MeV
• Covariant Spectator Theory of $np$ scattering: Deuteron form factors
• Two-pion exchange and strong form-factors in covariant field theories
• S-wave ${\pi }^0$ Production in pp Collision in a Covariant OBE Model
• Removal of singularities from the covariant spectator theory