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Type: Journal article
Title: Isospin-breaking effects in the extraction of isoscalar and isovector spectral functions from e⁺e⁻→ hadrons
Other Titles: Isospin-breaking effects in the extraction of isoscalar and isovector spectral functions from e(+)e(-)-> hadrons
Author: Maltman, Kim
Citation: Physical Review D, 1998; 58(1):14008
Publisher: American Physical Society
Issue Date: 1998
ISSN: 0556-2821
School/Discipline: School of Chemistry and Physics : Physics and Mathematical Physics
Statement of
Kim Maltman
Abstract: We investigate the problem of the extraction of the isovector and isoscalar spectral functions from data on e+e-→ hadrons, in the presence of non-zero isospin breaking. It is shown that the conventional approach to extracting the isovector spectral function in the ρ resonance region, in which only the isoscalar contribution associated with ω → ππ 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 (∼2%) in the isovector case (though relevant to precision tests of the CVC hypothesis), but very large (∼20%) in the case of the ω 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.
Rights: ©1998 American Physical Society
DOI: 10.1103/PhysRevD.58.014008
Appears in Collections:Special Research Centre for the Subatomic Structure of Matter publications

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