Eur. Phys. J. C (2007) 50: 781-791
https://doi.org/10.1140/epjc/s10052-007-0249-z

Regular Article - Theoretical Physics

Analysis of the vector form factors f⁺ _Kπ(Q²) and f^- _Kπ(Q²) with light-cone QCD sum rules

¹ Department of Physics, North China Electric Power University, Baoding, 071003, P.R. China
² Department of Modern Physics, University of Science and Technology of China, Hefei, 230026, P.R. China

^* e-mail: wangzgyiti@yahoo.com.cn

Received: 17 September 2006
Revised: 28 January 2007
Published online: 15 March 2007

Abstract

In this article, we calculate the vector form factors f⁺ _Kπ(Q²) and f^- _Kπ(Q²) within the framework of the light-cone QCD sum rule approach. The numerical values of f⁺ _Kπ(Q²) are compatible with existing theoretical calculations, and the central value of f⁺ _Kπ(0) (f⁺ _Kπ(0)=0.97) is in excellent agreement with the values from chiral perturbation theory and lattice QCD. The values of |f^- _Kπ(0)| are very large compared to the theoretical calculations and experimental data, and they cannot give any reliable prediction. At large momentum transfer with Q² > 5 GeV², the form factors f⁺ _Kπ(Q²) and |f^- _Kπ(Q²)| can either show the asymptotic behavior of or decrease more quickly than ; more experimental data are needed to select the ideal sum rules.