Instant form dynamics of one particle exchange models
- Department of Physics, State University of New York at Buffalo, Buffalo, New York 14260 (United States)
A general procedure for constructing instant form, one particle exchange models for two particle systems is developed. The procedure entails the construction of a mass operator which when used in conjunction with a free spin operator and a free Newton-Wigner position operator leads to an exactly Poincare invariant model. The method is applied to a simple model for {ital s}-wave pion-nucleon scattering. This model is derived from a quantum field theory which describes the interaction between pions, nucleons, and sigma mesons through the virtual processes {ital N}{r_reversible}{ital N}+{pi}, {pi}{r_reversible}{pi}+{sigma}, and {ital N}{r_reversible}{ital N}+{sigma}. The instant form version of this exchange model is compared with a front form version that was constructed previously. With the procedures used to ensure Poincare invariance, the instant form two-particle potentials are of the same form as the front form potentials; however, the pion-nucleon propagators that appear in the two-particle Lippmann-Schwinger equations are not the same. The instant form and front form models are fit to the same {ital s}-wave pion-nucleon phase shifts, and the resulting parameters are compared.
- OSTI ID:
- 256765
- Journal Information:
- Physical Review, C, Journal Name: Physical Review, C Journal Issue: 3 Vol. 52; ISSN PRVCAN; ISSN 0556-2813
- Country of Publication:
- United States
- Language:
- English
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