dorsal/arxiv
View SchemaMeson-Baryon-Baryon Vertex Function and the Ward-Takahashi Identity
| Authors | Siwen Wang, Manoj K. Banerjee |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/9607022 |
| URL | https://arxiv.org/abs/nucl-th/9607022 |
| DOI | 10.1103/PhysRevC.54.2883 |
| Journal | Phys.Rev.C54:2883-2893,1996 |
Abstract
Ohta proposed a solution for the well-known difficulty of satisfying the Ward-Takahashi identity for a photo-meson-baryon-baryon amplitude ($\gamma$MBB) when a dressed meson-baryon-baryon (MBB) vertex function is present. He obtained a form for the $\gamma$MBB amplitude which contained, in addition to the usual pole terms, longitudinal seagull terms which were determined entirely by the MBB vertex function. He arrived at his result by using a Lagrangian which yields the MBB vertex function at tree level. We show that such a Lagrangian can be neither hermitian nor charge conjugation invariant. We have been able to reproduce Ohta's result for the $\gamma$MBB amplitude using the Ward-Takahashi identity and no other assumption, dynamical or otherwise, and the most general form for the MBB and $\gamma$MBB vertices. However, contrary to Ohta's finding, we find that the seagull terms are not robust. The seagull terms extracted from the $\gamma$MBB vertex occur unchanged in tree graphs, such as in an exchange current amplitude. But the seagull terms which appear in a loop graph, as in the calculation of an electromagnetic form factor, are, in general, different. The whole procedure says nothing about the transverse part of the ($\gamma$MBB) vertex and its contributions to the amplitudes in question.
{
"annotation_id": "14baee06-7c24-4e20-8187-a1973eafe602",
"date_created": "2026-03-02T18:00:18.209000Z",
"date_modified": "2026-03-02T18:00:18.209000Z",
"file_hash": "916bb5745c29a0764dc17dc8cf9e0b56c1797fe88da0891c1da78c7594de9cba",
"private": false,
"record": {
"abstract": "Ohta proposed a solution for the well-known difficulty of satisfying the\nWard-Takahashi identity for a photo-meson-baryon-baryon amplitude ($\\gamma$MBB)\nwhen a dressed meson-baryon-baryon (MBB) vertex function is present. He\nobtained a form for the $\\gamma$MBB amplitude which contained, in addition to\nthe usual pole terms, longitudinal seagull terms which were determined entirely\nby the MBB vertex function. He arrived at his result by using a Lagrangian\nwhich yields the MBB vertex function at tree level. We show that such a\nLagrangian can be neither hermitian nor charge conjugation invariant. We have\nbeen able to reproduce Ohta\u0027s result for the $\\gamma$MBB amplitude using the\nWard-Takahashi identity and no other assumption, dynamical or otherwise, and\nthe most general form for the MBB and $\\gamma$MBB vertices. However, contrary\nto Ohta\u0027s finding, we find that the seagull terms are not robust. The seagull\nterms extracted from the $\\gamma$MBB vertex occur unchanged in tree graphs,\nsuch as in an exchange current amplitude. But the seagull terms which appear in\na loop graph, as in the calculation of an electromagnetic form factor, are, in\ngeneral, different. The whole procedure says nothing about the transverse part\nof the ($\\gamma$MBB) vertex and its contributions to the amplitudes in\nquestion.",
"arxiv_id": "nucl-th/9607022",
"authors": [
"Siwen Wang",
"Manoj K. Banerjee"
],
"categories": [
"nucl-th"
],
"doi": "10.1103/PhysRevC.54.2883",
"journal_ref": "Phys.Rev.C54:2883-2893,1996",
"title": "Meson-Baryon-Baryon Vertex Function and the Ward-Takahashi Identity",
"url": "https://arxiv.org/abs/nucl-th/9607022"
},
"schema_id": "dorsal/arxiv",
"source": {
"execution_id": "bd933e5f-b2cc-4b3a-96d2-2a7f32a9e8ed",
"id": "arXiv Dataset IDs",
"type": "Model",
"variant": "snapshot-2026-03-01",
"version": "0.1.0"
},
"user_id": 1000002
}