Search results for "Low-energy constants"
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Determination of the Chiral Couplings L10 and C87 from Semileptonic τ Decays
2008
Using recent precise hadronic tau-decay data on the V-A spectral function, and general properties of QCD such as analyticity, the operator product expansion and chiral perturbation theory, we get accurate values for the QCD chiral order parameters L_10^r(M_rho) and C_87^r(M_rho). These two low-energy constants appear at order p^4 and p^6, respectively, in the chiral perturbation theory expansion of the V-A correlator. At order p^4 we obtain L_10^r(M_rho) = -(5.22\pm 0.06)10^{-3}. Including in the analysis the two-loop (order p^6) contributions, we get L_10^r(M_rho) = -(4.06\pm 0.39)10^{-3} and C_87^r(M_rho) = (4.89\pm 0.19)10^{-3}GeV^{-2}. In the SU(2) chiral effective theory, the correspon…
Vanishing chiral couplings in the large-Nc resonance theory
2007
5 pages, 2 figures.-- PACS nrs.: 12.39.Fe; 11.15.Pg; 12.38.-t.-- ISI Article Identifier: 000247625300022.-- ArXiv pre-print available at: http://arxiv.org/abs/hep-ph/0611375