Order p^{6} chiral couplings from the scalar Kpi form factor
Abstract
Employing results from a recent determination of the scalar Kpi form factor F _{0} ^{ Kpi} within a coupled channel dispersion relation analysis [1], 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.
 Publication:

Journal of High Energy Physics
 Pub Date:
 February 2004
 DOI:
 10.1088/11266708/2004/02/047
 arXiv:
 arXiv:hepph/0401080
 Bibcode:
 2004JHEP...02..047J
 Keywords:

 Kaon Physics QCD Chiral Lagrangians;
 High Energy Physics  Phenomenology
 EPrint:
 19 pages, discussion of scale dependence of the chiral couplings added