6533b857fe1ef96bd12b468d

RESEARCH PRODUCT

Form-factors and current correlators: chiral couplingsL10r(μ) andC87r(μ) at NLO in 1/NC

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Using the resonance chiral theory Lagrangian, we perform a calculation of the vector and axial-vector two-point functions at the next-to-leading order (NLO) in the 1/N-C expansion. We have analyzed these correlators within the single-resonance approximation and have also investigated the corrections induced by a second multiplet of vector and axial-vector resonance states. Imposing the correct QCD short-distance constraints, one determines the difference of the two correlators Pi(t) equivalent to Pi(VV)(t)-Pi(AA)(t) in terms of the pion decay constant and resonance masses. Its low momentum expansion fixes then the low-energy chiral couplings L 1 0 and C 8 7 at NLO, keeping full control of their renormalization scale dependence. At mu(0) = 0.77GeV, we obtain L-10(r)(mu(0)) = (-4.4 +/- 0.9).10(-3) and C-87(r)(mu(0)) = (3.1 +/- 1.1).10(-5).