S-wave pion-nucleus dynamics in the sigma +. omega. model

Journal Article · Sun Jul 01 04:00:00 EDT 1979 · Phys. Rev., C; (United States)

DOI:https://doi.org/10.1103/PhysRevC.20.225· OSTI ID:5987969

Noble, J V

The sigma + ..omega.. model of nuclear forces has many desirable properties, including approximate chiral symmetry (partial conservation of axial vector current) and renormalizability, and it gives a good account of nuclear structure. It is therefore a useful framework within which to explore the modification of pion-nucleon dynamics in a nuclear medium, a problem which resists the usual soft-pion current-algebra cum analyticity techniques owing to the presence of anomalous thresholds (nuclear structure effects). It is found that through order G/sup 4/ (for pion elastic scattering) and G/sup 3/ (for pion absorption or emission) the chiral invariance ensures sufficient cancellations between otherwise large terms so as to produce little renormalization of free-particle dynamics. Moreover, the pseudoscalar-coupled sigma + ..omega.. model is equivalent in pion emission or absorption, through O (G/sup 3/), to a pseudovector-coupled phenomenological model (with no ..pi..-sigma interaction, but with a form of partially conserved axial vector current). Thus, the question of whether one can distinguish experimentally between pseudoscalar and pseudovector ..pi..NN coupling is probably meaningless.

• Research Organization: Department of Physics, University of Washington, Seattle, Washington 98195
• OSTI ID: 5987969
• Journal Information: Phys. Rev., C; (United States), Journal Name: Phys. Rev., C; (United States) Vol. 20:1; ISSN PRVCA
• Country of Publication: United States
• Language: English

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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
CHIRAL SYMMETRY
CURRENT ALGEBRA
ELASTIC SCATTERING
HADRON-HADRON INTERACTIONS
INTERACTIONS
MATHEMATICAL MODELS
MESON-BARYON INTERACTIONS
MESON-NUCLEON INTERACTIONS
NUCLEAR FORCES
NUCLEAR STRUCTURE
PARTIAL WAVES
PARTICLE INTERACTIONS
PARTICLE MODELS
PCAC THEORY
PION-NUCLEON INTERACTIONS
RENORMALIZATION
S WAVES
SCATTERING
SCATTERING LENGTHS
SIGMA MODEL
SYMMETRY