|Source||United States Department of Energy Office of Scientific and Technical Information|
|Subject Keyword||PHYSICS ♦ COUPLING ♦ CROSS SECTIONS ♦ DISPERSION RELATIONS ♦ ELEMENTARY PARTICLES ♦ FIELD THEORY ♦ INTERACTIONS ♦ ISOSPIN ♦ NUCLEONS ♦ PARTICLE MODELS ♦ PIONS ♦ SCATTERING ♦ SPECTRAL SHIFT ♦ SPIN|
|Abstract||Pion-nucleon scattering is described as the flipping and non-flipping of the spin and isotopic spin of the nucleon. These are expressed in terms of scattering amplitudes in pure isotopic spin states, and in turn are expressed in terms of phase shift. The basic assumptions needed for the dispersion theory to become more nearly a dynamical theory of the pion system are: causality, unitary condition, crossing theorem, high energy behavior of sigma ( omega ), and behavior of S( omega ), in the unphysical region, O < omega < mu . This dynamical theory must allow exact calculations of the four amplitudes of the pion system. Dispersion relations are utilized in the investigation of sign ambiguity of phase shifts, Fermi-Yang ambiguity of phase shifts, and the determination of the coupling constant f/sup 2/. The work of Puppi and Stanghellini in dispersion relations is briefly discussed. (B.O.G.)|
|Learning Resource Type||Article|
|Publisher Department||Universita, Bologna|
|Issue Number||Suppl 2|
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