dorsal/arxiv
View SchemaA quark model framework for the study of nuclear medium effects
| Authors | Q. Zhao, J. S. Al-Khalili, R. C. Johnson |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/0408011 |
| URL | https://arxiv.org/abs/nucl-th/0408011 |
| DOI | 10.1088/0954-3899/30/9/014 |
| Journal | J.Phys. G30 (2004) 1153-1162 |
Abstract
A quark-model framework for studying nuclear medium effects on nucleon resonances is described and applied here to pion photoproduction on the deuteron, which is the simplest composite nucleon system and serves as a first test case. Pion photoproduction on nuclei is discussed within a chiral constituent quark model in which the quark degrees of freedom are explicitly introduced through an effective chiral Lagrangian for the quark-pseudoscalar-meson coupling. The advantage of this model is that a complete set of nucleon resonances can be systematically included with a limited number of parameters. Also, the systematic description of the nucleon and its resonances at quark level allows us to self-consistently relate the nuclear medium's influence on the baryon properties to the intrinsic dynamic aspects of the baryons. As the simplest composite nucleus, the deuteron represents the first application of this effective theory for meson photoproduction on light nuclei. The influence of the medium on the transition operators for a free nucleon is investigated in the Delta resonance region. No evidence is found for a change of the Delta properties in the pion photoproduction reaction on the deuteron since the nuclear medium here involves just one other nucleon and the low binding energy implies low nuclear density. However, we show that the reaction mechanism is in principle sensitive to changes of Delta properties that would be produced by the denser nuclear medium of heavier nuclei through the modification of the quark model parameters.
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"abstract": "A quark-model framework for studying nuclear medium effects on nucleon\nresonances is described and applied here to pion photoproduction on the\ndeuteron, which is the simplest composite nucleon system and serves as a first\ntest case. Pion photoproduction on nuclei is discussed within a chiral\nconstituent quark model in which the quark degrees of freedom are explicitly\nintroduced through an effective chiral Lagrangian for the\nquark-pseudoscalar-meson coupling. The advantage of this model is that a\ncomplete set of nucleon resonances can be systematically included with a\nlimited number of parameters. Also, the systematic description of the nucleon\nand its resonances at quark level allows us to self-consistently relate the\nnuclear medium\u0027s influence on the baryon properties to the intrinsic dynamic\naspects of the baryons. As the simplest composite nucleus, the deuteron\nrepresents the first application of this effective theory for meson\nphotoproduction on light nuclei. The influence of the medium on the transition\noperators for a free nucleon is investigated in the Delta resonance region. No\nevidence is found for a change of the Delta properties in the pion\nphotoproduction reaction on the deuteron since the nuclear medium here involves\njust one other nucleon and the low binding energy implies low nuclear density.\nHowever, we show that the reaction mechanism is in principle sensitive to\nchanges of Delta properties that would be produced by the denser nuclear medium\nof heavier nuclei through the modification of the quark model parameters.",
"arxiv_id": "nucl-th/0408011",
"authors": [
"Q. Zhao",
"J. S. Al-Khalili",
"R. C. Johnson"
],
"categories": [
"nucl-th"
],
"doi": "10.1088/0954-3899/30/9/014",
"journal_ref": "J.Phys. G30 (2004) 1153-1162",
"title": "A quark model framework for the study of nuclear medium effects",
"url": "https://arxiv.org/abs/nucl-th/0408011"
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