dorsal/arxiv
View SchemaIsospin Breaking Effects in the Extraction of Isoscalar and Isovector Spectral Functions From $e^+e^-\to hadrons$
| Authors | Kim Maltman |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/9709069 |
| URL | https://arxiv.org/abs/nucl-th/9709069 |
| DOI | 10.1103/PhysRevD.58.014008 |
| Journal | Phys.Rev. D58 (1998) 014008 |
Abstract
We investigate the problem of the extraction of the isovector and isoscalar spectral functions from data on $e^+e^-\to hadrons$, in the presence of non-zero isospin breaking. It is shown that the conventional approach to extracting the isovector spectral function in the $\rho$ resonance region, in which only the isoscalar contribution associated with $\omega\to \pi\pi$ is subtracted, fails to fully remove the effects of the isoscalar component of the electromagnetic current. The additional subtractions required to extract the pure isovector and isoscalar spectral functions are estimated using results from QCD sum rules. It is shown that the corrections are small ($\sim 2%$) in the isovector case (though relevant to precision tests of CVC), but very large ($\sim 20%$) in the case of the $\omega$ contribution to the isoscalar spectral function. The reason such a large effect is natural in the isoscalar channel is explained, and implications for other applications, such as the extraction of the sixth order chiral low-energy constant, $Q$, are discussed.
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"abstract": "We investigate the problem of the extraction of the isovector and isoscalar\nspectral functions from data on $e^+e^-\\to hadrons$, in the presence of\nnon-zero isospin breaking. It is shown that the conventional approach to\nextracting the isovector spectral function in the $\\rho$ resonance region, in\nwhich only the isoscalar contribution associated with $\\omega\\to \\pi\\pi$ is\nsubtracted, fails to fully remove the effects of the isoscalar component of the\nelectromagnetic current. The additional subtractions required to extract the\npure isovector and isoscalar spectral functions are estimated using results\nfrom QCD sum rules. It is shown that the corrections are small ($\\sim 2%$) in\nthe isovector case (though relevant to precision tests of CVC), but very large\n($\\sim 20%$) in the case of the $\\omega$ contribution to the isoscalar spectral\nfunction. The reason such a large effect is natural in the isoscalar channel is\nexplained, and implications for other applications, such as the extraction of\nthe sixth order chiral low-energy constant, $Q$, are discussed.",
"arxiv_id": "nucl-th/9709069",
"authors": [
"Kim Maltman"
],
"categories": [
"nucl-th",
"hep-ph"
],
"doi": "10.1103/PhysRevD.58.014008",
"journal_ref": "Phys.Rev. D58 (1998) 014008",
"title": "Isospin Breaking Effects in the Extraction of Isoscalar and Isovector Spectral Functions From $e^+e^-\\to hadrons$",
"url": "https://arxiv.org/abs/nucl-th/9709069"
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