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HK: Hadronen und Kerne
HK 20: Structure of Baryons, Mesons III, Theory
HK 20.3: Talk
Monday, March 16, 1998, 17:45–18:00, H
π“σ”- Scattering and the Softening of the πNN Form Factor — •R. B"ockmann, O. Krehl, S. Krewald, and J. Speth — Institut f"ur Kernphysik, Forschungszentrum J"ulich
Meson exchange NN interaction models require a relatively hard πNN form factor with values for the cutoff mass of more than 1.3 GeV using a standard monopole parameterization in order to reproduce the deuteron properties, especially the asymptotic D- to S-wave ratio and the quadrupole moment, whereas other sources point to a rather soft πNN form factor characterized by Λπ NN ≈ 0.8 GeV[1].
The inclusion of the correlated π ρ exchange[2] in the two-nucleon interaction allows for a reduction of Λπ NN to 1.0 GeV.
A possible solution to the remaining discrepancy can be found in the consideration of a correlated π“σ” exchange which yields obviously a short-ranged contribution in the channel with pionic quantum numbers and thus an additional tensor force. First results of π“σ” correlations and the influence on the πNN form factor are discussed.
[1] A.W. Thomas and K. Holinde, Phys. Rev. Lett. 63, 2025 (1989)
[2] G. Janssen, K. Holinde and J. Speth, Phys. Rev. C 54, 2218 (1996)