Employing results from a recent determination of the scalar Kpi form factor F 0 Kpi within a coupled channel dispersion relation analysis , in this work we calculate the slope and curvature of F 0 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 F 0 Kpi(t) in chiral perturbation theory at order p 6 , enable to estimate the Script O(p 6) chiral constants C 12 r (M rho) = (0.3+/-5.4).10-7 and (C 12 r +C 34 r )(M rho) = (3.2+/-1.5).10-6 . Our findings also allow to estimate the contribution coming from the C i to the vector form factor F + Kpi(0) which is a crucial ingredient for a precise determination of |V us | from K l3 decays. Our result F + Kpi(0)| C i 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.
Journal of High Energy Physics
- Pub Date:
- February 2004
- Kaon Physics QCD Chiral Lagrangians;
- High Energy Physics - Phenomenology
- 19 pages, discussion of scale dependence of the chiral couplings added