Analysis of the $\Sigma -n$ form factors with light-cone QCD sum rules

Abstract

In this work, we study the four form-factors $f_1(Q^2)$, $f_2(Q^2)$, $g_1(Q^2)$ and $g_2(Q^2)$ of the $\Sigma \to n$ in the framework of the light-cone QCD sum rules approach up to twist-6 three valence quark light-cone distribution amplitudes. The $f_1(0)$ is the basic input parameter in extracting the CKM matrix element $|V_{us}|$ from the hyperon decays. The four form-factors $f_1(Q^2)$, $f_2(Q^2)$, $g_1(Q^2)$ and $g_2(Q^2)$ at intermediate and large momentum transfers with $Q^2>3Ge{V}^2$ have significant contributions from the end-point (soft) terms. The numerical values of the four form-factors $f_1(0)$, $f_2(0)$, $g_1(0)$ and $g_2(0)$ are compatible with the experimental data and theoretical calculations (in magnitude); although the uncertainties are large.

Comments: 16 pages, 4 figures, second version, typos corrected, the article is published in "J. Phys. G34 (2007) 493-504" not in "J. Phys. G34 (2007) 335-346"