dorsal/arxiv
View SchemaDilepton production in elementary and in heavy ion reactions
| Authors | Christian Fuchs, Amand Faessler |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/0402102 |
| URL | https://arxiv.org/abs/nucl-th/0402102 |
| DOI | 10.1016/j.ppnp.2004.02.011 |
| Journal | Prog.Part.Nucl.Phys. 53 (2004) 59-75 |
Abstract
We present a unified description of the vector meson and dilepton production in elementary and in heavy ion reactions. The production of vector mesons ($\rho,\omega,\phi$) is described via the excitation of nucleon resonances ($R$). The theoretical framework is an extended vector meson dominance model (eVMD) for resonance decays $R\longmapsto NV$ with arbitrary spin which is covariant and kinematically complete. The eVMD includes thereby excited vector meson states in the transition form factors. The model has successfully been applied to $\omega$ and $\phi$ production in $p+p$ reactions. The same model is used to describe the dilepton production in elementary reactions where corresponding data are well reproduced. However, when the model is applied to heavy ion reactions in the BEVALAC/SIS energy range the experimental dilepton spectra measured by the DLS Collaboration are significantly underestimated at small invariant masses. In view of this fact we discuss further medium effects: One is a substantial collisional broadening of the $\rho$ and in particular of the $\omega$ meson in the vicinity of the $\rho/\omega$-peak. The second medium effect is the destruction of quantum interference in a dense medium. A decoherent dilepton emission through vector mesons decays enhances the corresponding low mass dilepton yield in heavy ion reactions and improves the agreement with existing data.
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"abstract": "We present a unified description of the vector meson and dilepton production\nin elementary and in heavy ion reactions. The production of vector mesons\n($\\rho,\\omega,\\phi$) is described via the excitation of nucleon resonances\n($R$). The theoretical framework is an extended vector meson dominance model\n(eVMD) for resonance decays $R\\longmapsto NV$ with arbitrary spin which is\ncovariant and kinematically complete. The eVMD includes thereby excited vector\nmeson states in the transition form factors. The model has successfully been\napplied to $\\omega$ and $\\phi$ production in $p+p$ reactions. The same model is\nused to describe the dilepton production in elementary reactions where\ncorresponding data are well reproduced. However, when the model is applied to\nheavy ion reactions in the BEVALAC/SIS energy range the experimental dilepton\nspectra measured by the DLS Collaboration are significantly underestimated at\nsmall invariant masses. In view of this fact we discuss further medium effects:\nOne is a substantial collisional broadening of the $\\rho$ and in particular of\nthe $\\omega$ meson in the vicinity of the $\\rho/\\omega$-peak. The second medium\neffect is the destruction of quantum interference in a dense medium. A\ndecoherent dilepton emission through vector mesons decays enhances the\ncorresponding low mass dilepton yield in heavy ion reactions and improves the\nagreement with existing data.",
"arxiv_id": "nucl-th/0402102",
"authors": [
"Christian Fuchs",
"Amand Faessler"
],
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"doi": "10.1016/j.ppnp.2004.02.011",
"journal_ref": "Prog.Part.Nucl.Phys. 53 (2004) 59-75",
"title": "Dilepton production in elementary and in heavy ion reactions",
"url": "https://arxiv.org/abs/nucl-th/0402102"
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