In this article, we calculate the form factors and the coupling constant of
the vertex DsββDsβΟ using the three-point QCD sum rules. We
consider the contributions of the vacuum condensates up to dimension 7 in the
operator product expansion(OPE). And all possible off-shell cases are
considered, Ο, Dsβ and Dsββ, resulting in three different form
factors. Then we fit the form factors into analytical functions and extrapolate
them into time-like regions, which giving the coupling constant for the
process. Our analysis indicates that the coupling constant for this vertex is
GDsβDsΟβ=4.12Β±0.70GeVβ1. The results of this work are very useful
in the other phenomenological analysis. As an application, we calculate the
coupling constant for the decay channel DsβββDsβΞ³ and
analyze the width of this decay with the assumption of the vector meson
dominance of the intermediate Ο(1020). Our final result about the decay
width of this decay channel is Ξ=0.59Β±0.15keV.Comment: arXiv admin note: text overlap with arXiv:1501.03088 by other author