dorsal/arxiv
View SchemaChiral Perturbation Theory and the pp -> pp pi0 Reaction Near Threshold
| Authors | T. Sato, T. -S. H. Lee, F. Myhrer, K. Kubodera |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/9704003 |
| URL | https://arxiv.org/abs/nucl-th/9704003 |
| DOI | 10.1103/PhysRevC.56.1246 |
| Journal | Phys.Rev.C56:1246-1255,1997 |
Abstract
A chiral-perturbative consideration of the near-threshold pp -> pp pi0 reaction indicates that the pion-rescattering term has a substantial energy and momentum dependence. The existing calculations that incorporate this dependence give pion rescattering contributions significantly larger than those of the conventional treatment, and this enhanced rescattering term interferes destructively with the one-body impulse term, leading to theoretical cross sections that are much smaller than the observed values. However, since the existing calculations are based on coordinate-space representation, they involve a number of simplifying assumptions about the energy-momentum flow in the rescattering diagram, even though the delicate interplay between the one-body and two-body terms makes it desirable to avoid these kinematical assumptions. We carry out here a momentum-space calculation that retains the energy-momentum dependence of the vertices as predicted by chiral perturbation theory. Our improved treatment increases the rescattering amplitude by a factor of 3 over the value obtained in the r-space calculations. The pp -> pp pi0 transition amplitude, which is now dominated by the rescattering term, leads to the cross section much larger than what was reported in the approximate r-space calculations. Thus, the extremely small cross sections obtained in the previous chiral perturbative treatments of this reaction should be considered as an accidental consequence of the approximations employed rather than a general feature.
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"abstract": "A chiral-perturbative consideration of the near-threshold pp -\u003e pp pi0\nreaction indicates that the pion-rescattering term has a substantial energy and\nmomentum dependence. The existing calculations that incorporate this dependence\ngive pion rescattering contributions significantly larger than those of the\nconventional treatment, and this enhanced rescattering term interferes\ndestructively with the one-body impulse term, leading to theoretical cross\nsections that are much smaller than the observed values. However, since the\nexisting calculations are based on coordinate-space representation, they\ninvolve a number of simplifying assumptions about the energy-momentum flow in\nthe rescattering diagram, even though the delicate interplay between the\none-body and two-body terms makes it desirable to avoid these kinematical\nassumptions. We carry out here a momentum-space calculation that retains the\nenergy-momentum dependence of the vertices as predicted by chiral perturbation\ntheory. Our improved treatment increases the rescattering amplitude by a factor\nof 3 over the value obtained in the r-space calculations. The pp -\u003e pp pi0\ntransition amplitude, which is now dominated by the rescattering term, leads to\nthe cross section much larger than what was reported in the approximate r-space\ncalculations. Thus, the extremely small cross sections obtained in the previous\nchiral perturbative treatments of this reaction should be considered as an\naccidental consequence of the approximations employed rather than a general\nfeature.",
"arxiv_id": "nucl-th/9704003",
"authors": [
"T. Sato",
"T. -S. H. Lee",
"F. Myhrer",
"K. Kubodera"
],
"categories": [
"nucl-th"
],
"doi": "10.1103/PhysRevC.56.1246",
"journal_ref": "Phys.Rev.C56:1246-1255,1997",
"title": "Chiral Perturbation Theory and the pp -\u003e pp pi0 Reaction Near Threshold",
"url": "https://arxiv.org/abs/nucl-th/9704003"
},
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