dorsal/arxiv
View SchemaSigma Terms of Light-Quark Hadrons
| Authors | V. V. Flambaum, A. Hoell, P. Jaikumar, C. D. Roberts, S. V. Wright |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/0510075 |
| URL | https://arxiv.org/abs/nucl-th/0510075 |
| DOI | 10.1007/s00601-005-0123-1 |
| Journal | Few Body Syst.38:31-51,2006 |
Abstract
A calculation of the current-quark mass dependence of hadron masses can help in using observational data to place constraints on the variation of nature's fundamental parameters. A hadron's sigma-term is a measure of this dependence. The connection between a hadron's sigma-term and the Feynman-Hellmann theorem is illustrated with an explicit calculation for the pion using a rainbow-ladder truncation of the Dyson-Schwinger equations: in the vicinity of the chiral limit sigma_pi = m_pi/2. This truncation also provides a decent estimate of sigma_rho because the two dominant self-energy corrections to the rho-meson's mass largely cancel in their contribution to sigma_rho. The truncation is less accurate for the omega, however, because there is little to compete with an omega->rho+pi self-energy contribution that magnifies the value of sigma_omega by ~25%. A Poincare' covariant Faddeev equation, which describes baryons as composites of confined-quarks and -nonpointlike-diquarks, is solved to obtain the current-quark mass dependence of the masses of the nucleon and Delta, and thereby sigma_N and sigma_Delta. This "quark-core" piece is augmented by the "pion cloud" contribution, which is positive. The analysis yields sigma_N~60MeV and sigma_Delta~50MeV.
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"abstract": "A calculation of the current-quark mass dependence of hadron masses can help\nin using observational data to place constraints on the variation of nature\u0027s\nfundamental parameters. A hadron\u0027s sigma-term is a measure of this dependence.\nThe connection between a hadron\u0027s sigma-term and the Feynman-Hellmann theorem\nis illustrated with an explicit calculation for the pion using a rainbow-ladder\ntruncation of the Dyson-Schwinger equations: in the vicinity of the chiral\nlimit sigma_pi = m_pi/2. This truncation also provides a decent estimate of\nsigma_rho because the two dominant self-energy corrections to the rho-meson\u0027s\nmass largely cancel in their contribution to sigma_rho. The truncation is less\naccurate for the omega, however, because there is little to compete with an\nomega-\u003erho+pi self-energy contribution that magnifies the value of sigma_omega\nby ~25%. A Poincare\u0027 covariant Faddeev equation, which describes baryons as\ncomposites of confined-quarks and -nonpointlike-diquarks, is solved to obtain\nthe current-quark mass dependence of the masses of the nucleon and Delta, and\nthereby sigma_N and sigma_Delta. This \"quark-core\" piece is augmented by the\n\"pion cloud\" contribution, which is positive. The analysis yields sigma_N~60MeV\nand sigma_Delta~50MeV.",
"arxiv_id": "nucl-th/0510075",
"authors": [
"V. V. Flambaum",
"A. Hoell",
"P. Jaikumar",
"C. D. Roberts",
"S. V. Wright"
],
"categories": [
"nucl-th",
"astro-ph",
"hep-lat",
"hep-ph",
"nucl-ex"
],
"doi": "10.1007/s00601-005-0123-1",
"journal_ref": "Few Body Syst.38:31-51,2006",
"title": "Sigma Terms of Light-Quark Hadrons",
"url": "https://arxiv.org/abs/nucl-th/0510075"
},
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