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Title: Unitary, relativistic resonance model for [pi][ital N] scattering

Journal Article · · Physical Review, C (Nuclear Physics); (United States)
 [1];  [2]
  1. College of William and Mary, Williamsburg, Virginia 23185 (United States) Continuous Electron Beam Accelerator Facility, 12000 Jefferson Ave., Newport News, Virginia 23606 (United States)
  2. College of William and Mary, Williamsburg, Virginia 23185 (United States)

Pion nucleon scattering up to 600 MeV laboratory kinetic energy is described by a manifestly covariant wave equation in which the pion is restricted to its mass shell. The kernel of the equation includes nucleon ([ital N]), Roper ([ital N][sup *]), delta ([Delta]), and [ital D][sub 13] poles, with their corresponding crossed pole terms approximated by contact interactions, and contact [sigma]- and [rho]-like exchange terms. The [pi][ital NN] vertex is treated as a mixture of [gamma][sup 5] and [gamma][sup [mu]][gamma][sup 5] coupling, with a mixing parameter [lambda] chosen so that the dressed nucleon pole will be unshifted by the interaction. Chiral symmetry is maintained at threshold. The resonance contributions are fully unitarized by the equation, with their widths determined by the dynamics included in the model. The [Delta] and [ital D][sub 13] are treated as pure spin 3/2 particles, with no spin 1/2 amplitude in the [ital S] channel. The complete development of this model, which gives a very good fit to all the data up to 600 MeV, is presented.

DOE Contract Number:
FG05-88ER40435
OSTI ID:
6818396
Journal Information:
Physical Review, C (Nuclear Physics); (United States), Vol. 47:2; ISSN 0556-2813
Country of Publication:
United States
Language:
English