Revisiting the vector form factor at next-to-leading order in 1/NC

Using the Resonance Chiral Theory lagrangian, we perform a calculation of the vector form factor of the pion at the next-to-leading order (NLO) in the 1/N-C expansion. Imposing the correct QCD short-distance constraints, one determines it in terms of F, G(V), F-A and resonance masses. Its low momentum expansion fixes then the low-energy chiral couplings L-9 and C-88 - C-90 at NLO, keeping full control of their renormalization scale dependence. At mu(0) = 0.77 GeV, we obtain L-9(r)(mu(0)) = (7.6 +/- 0.6) . 10(-3) and C-88(r)(mu(0)) - C-90(r)(mu(0)) = (-4.5 +/- 0.5) . 10(-5).