Relativistic generalizations of simple pion-nucleon models

Journal Article · Wed Apr 01 04:00:00 EST 1981 · Phys. Rev., C; (United States)

DOI:https://doi.org/10.1103/PhysRevC.23.1660· OSTI ID:6788438

McLeod, R J; Ernst, D J

A relativistic, partial wave N/D dispersion theory is developed for low energy pion-nucleon elastic scattering. The theory is simplified by treating crossing symmetry only to lowest order in the inverse nucleon mass. The coupling of elastic scattering to inelastic channels is included by taking the necessary inelasticity from experimental data. Three models are examined: pseudoscalar coupling of pions and nucleons, pseudovector coupling, and a model in which all intermediate antinucleons are projected out of the amplitude. The phase shifts in the dominant P/sub 33/ channel are quantitatively reproduced for P/sub lab/< or =1.2 GeV/c with a pion-nucleon vertex of range 1110 MeV/c. We find that there are large (not of the order of the inverse nucleon mass) kinematic corrections to Chew-Low models, and that the Chew-Low model is successful because a reduction in the pion-nucleon cutoff provides a remarkable compensation for the large kinematic corrections. The intermediate antinucleon states are found to provide a significant fraction of the interaction in both S and P waves, and the model which explicitly removes them is incompatible with the P/sub 33/ phase shifts. Thus a model of the pion-nucleon interaction which does not include antinucleon degrees of freedom is found to be unphysical.

• Research Organization: Physics Department, Texas A and M University, College Station, Texas 77843
• OSTI ID: 6788438
• Journal Information: Phys. Rev., C; (United States), Journal Name: Phys. Rev., C; (United States) Vol. 23:4; ISSN PRVCA
• Country of Publication: United States
• Language: English

Related Subjects

653003* -- Nuclear Theory-- Nuclear Reactions &amp; Scattering
653007 -- Nuclear Theory-- Nuclear Models-- (-1987)
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
COUPLING CONSTANTS
CROSSING SYMMETRY
ELASTIC SCATTERING
ENERGY RANGE
HADRON-HADRON INTERACTIONS
INELASTIC SCATTERING
INTERACTIONS
MATHEMATICAL MODELS
MESON-BARYON INTERACTIONS
MESON-NUCLEON INTERACTIONS
NUCLEAR MODELS
PARTICLE INTERACTIONS
PHASE SHIFT
PION-NUCLEON INTERACTIONS
RELATIVISTIC RANGE
SCATTERING
SHELL MODELS
SYMMETRY