
Employing results from a recent determination of the scalar Kpi form factor F0(Kpi) within a coupled channel dispersion relation analysis [1], in this work we calculate the slope and curvature of F0(Kpi)(t) at zero momentum transfer. Knowledge of the slope and curvature of the scalar Kpi form factor, together with a recently calculated expression for F0(Kpi)(t) in chiral perturbation theory at order p(6), enable to estimate the O(p(6)) chiral constants C12(r) (Mrho) = (0.3 +/ 5.4) . 10(7) and (C12(r) + C34(r)) (Mrho) = (3.2 +/ 1.5) . 10(6). Our findings also allow to estimate the contribution coming from the Ci to the vector form factor F+(Kpi)(0) which is a crucial ingredient for a precise determination of \Vus\ from Kl3 decays. Our result F+(Kpi)(0)\Ci(r) = 0.018 +/ 0.009, though inflicted with large uncertainties, is in perfect agreement with a previous estimate by Leutwyler and Roos already made twenty years ago.
