dorsal/arxiv
View SchemaLeading-order Corrections of a Dynamical Model for Electromagnetic Pion Production Reactions
| Authors | T. Sato, T. -S. H. Lee, T. Nakamura |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/0411013 |
| URL | https://arxiv.org/abs/nucl-th/0411013 |
Abstract
By applying a unitary transformation method, we have derived the leading-order corrections on the effective Hamiltonian of a dynamical model developed in Phys. Rev. C54, 2660 (1996) for electromagnetic pion production reactions. The resulting energy-independent one-loop corrections on the baryon masses and the gamma N -> Delta vertex interaction are associated with the structure of the nucleon and Delta and have been calculated within a constituent quark model. We find that the one-loop corrections on the magnetic M1 transition of the gamma N -> Delta are very small, while their contributions to the electric E2 and Coulomb C2 transitions are found to be in opposite signs of that due to pion cloud effects associated with the scattering states. Our results further indicate that the determination of the nonspherical L=2 components of the constituent quark wavefunctions of N and Delta from the extracted empirical E2 and C2 form factors requires a rigorous and complete calculation of meson cloud effects. We also find that the one-loop corrections on the non-resonant pion production operator can resolve the difficulty in describing the near threshold gamma p -> pi^0 p reaction. Possible future developments are discussed.
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"abstract": "By applying a unitary transformation method, we have derived the\nleading-order corrections on the effective Hamiltonian of a dynamical model\ndeveloped in Phys. Rev. C54, 2660 (1996) for electromagnetic pion production\nreactions. The resulting energy-independent one-loop corrections on the baryon\nmasses and the gamma N -\u003e Delta vertex interaction are associated with the\nstructure of the nucleon and Delta and have been calculated within a\nconstituent quark model. We find that the one-loop corrections on the magnetic\nM1 transition of the gamma N -\u003e Delta are very small, while their contributions\nto the electric E2 and Coulomb C2 transitions are found to be in opposite signs\nof that due to pion cloud effects associated with the scattering states. Our\nresults further indicate that the determination of the nonspherical L=2\ncomponents of the constituent quark wavefunctions of N and Delta from the\nextracted empirical E2 and C2 form factors requires a rigorous and complete\ncalculation of meson cloud effects. We also find that the one-loop corrections\non the non-resonant pion production operator can resolve the difficulty in\ndescribing the near threshold gamma p -\u003e pi^0 p reaction. Possible future\ndevelopments are discussed.",
"arxiv_id": "nucl-th/0411013",
"authors": [
"T. Sato",
"T. -S. H. Lee",
"T. Nakamura"
],
"categories": [
"nucl-th"
],
"title": "Leading-order Corrections of a Dynamical Model for Electromagnetic Pion Production Reactions",
"url": "https://arxiv.org/abs/nucl-th/0411013"
},
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