Analysis of the vector form factors $f_{K\pi }^{+}(Q^2)$ and $f_{K\pi }^{-}(Q^2)$ with light-cone QCD sum rules

Abstract

In this article, we calculate the vector form factors $f_{K\pi }^{+}(Q^2)$ and $f_{K\pi }^{-}(Q^2)$ within the framework of the light-cone QCD sum rules approach. The numerical values of the $f_{K\pi }^{+}(Q^2)$ are compatible with the existing theoretical calculations, the central value of the $f_{K\pi }^{+}(0)$, $f_{K\pi }^{+}(0)=0.97$, is in excellent agreement with the values from the chiral perturbation theory and lattice QCD. The values of the $|f_{K\pi }^{-}(0)|$ are very large comparing with the theoretical calculations and experimental data, and can not give any reliable predictions. At large momentum transfers with $Q^2>5Ge{V}^2$, the form factors $f_{K\pi }^{+}(Q^2)$ and $|f_{K\pi }^{-}(Q^2)|$ can either take up the asymptotic behavior of $\frac{1}{Q^2}$ or decrease more quickly than $\frac{1}{Q^2}$, more experimental data are needed to select the ideal sum rules.

Comments: 22 pages, 16 figures, revised version, to appear in Eur. Phys. J. C