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

• Main Authors: Peña, M. T, Gross, Franz, Surya, Yohanes
• Format: Journal Article
• Language: English
• Published: 30-05-1996
• Subjects: Physics - Nuclear Theory
• DOI: 10.48550/arxiv.nucl-th/9605041

Phys.Rev.C54:2235-2239,1996 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.