Form-factors and current correlators: chiral couplings L10(mu) and C87(mu) at NLO in 1/N(C)
Abstract
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) = PiVV(t)- PiAA(t) in terms of the pion decay constant and resonance masses. Its low momentum expansion fixes then the low-energy chiral couplings L10 and C87 at NLO, keeping full control of their renormalization scale dependence. At mu0=0.77 GeV, we obtain L10(mu0) = (-4.4 0.9)10-3 and C87r(mu0)=(3.1 1.1)10-5.