Two-pion Contribution Research Articles

Research ofp-pScattering at 10 Mev by the Dispersion Relation

Nucleon-nucleon scattering is studied by the dispersion relation as a function of momentum transfer. The spectra functions arising from the two-pion contribution are calculated. The theory is applied to p-p scattering at 10 Mev. It is shown that such a dispersion relation may be correct, but a definite conclusion as to its correctness cannot be reached. It is indicated that in such a dispersion relation the two-pion contribution (and possibly higher pion contributions) appear from lower energies. The two-pion effect is quite large at 10 Mev. (auth)

K-meson-nucleon scattering

Assuming that the isotropy of K Open image in new window -scattering inI=1 is due to the cancellation ofp-wave contributions coming from the hyperon cuts and the two-pion cut, we investigate the K Open image in new window -scattering inI=1,s-state and inI=0,s-,p1/2-,p3/2-states. Qualitative agreement with the present experimental situation is obtained. Using crossing symmetry, the two-pion contribution in\(\bar K\) Open image in new window -scattering is also considered.

Application of dispersion relations to nucleon-nucleon scattering: The two-pion contribution

The two-pion contribution to the amplitude for nucleon-nucleon scattering is computed in terms of the invariant amplitudes which characterize the four-body Green's function of the pion nucleon system. The dependence of this contribution upon the momentum transfer of the two-nucleon system is completely exhibited. A general method is described for the derivation of symmetry properties for the invariant coefficients in the expansion of the scattering amplitude in spinor space.

Dispersion Relations in Nucleon-Nucleon Scattering

Two-pion contribution to the absorptive part of nucleon-nucleon scattering amplitudes in the unphysical region is calculated using the dispersion for pion-nucleon scattering. The dispersion relations with this absorptive part are used for analyzing nucleon-nucleon scattering data at low energy and at moderate energy, and we find good agreement if we choose the coupling constant as f2 / 4π= 0.08 ±0.01.