QCD sum-rule consistency of lowest-lying q overlineq scalar resonances
Abstract
We investigate lowest-lying scalar meson properties predicted from QCD Laplace sum rules based upon isovector and isoscalar non-strange overlineqq currents. The hadronic content of these sum rules incorporates deviations from the narrow resonance approximation anticipated from physical resonance widths. The field theoretical content of these sum rules incorporates purely perturbative QCD contributions to three-loop order, the direct single-instanton contribution in the instanton liquid model, and leading contributions from QCD-vacuum condensates. In the isovector channel, the results we obtain are compatible with a0(1450) being the lowest-lying q overlineq resonance, and are indicative of a non-q overlineq interpretation for a0(980). In the isoscalar channel, the results we obtain are compatible with the lowest lying q overlineq resonance being f0(980) or a state somewhat lighter than f0(980) whose width is less than half of its mass. A linear sigma-model interpretation of the lowest-lying resonance's coupling, when compared to the coupling predicted by sum rules, is indicative of a renormalization-group invariant light-quark mass between 4 and 6 MeV.
- Publication:
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Nuclear Physics A
- Pub Date:
- April 1998
- DOI:
- 10.1016/S0375-9474(98)00119-5
- arXiv:
- arXiv:hep-ph/9801415
- Bibcode:
- 1998NuPhA.633..279E
- Keywords:
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- High Energy Physics - Phenomenology
- E-Print:
- Latex, 40 pages, 17 figures