${\eta }_{b}B{B}^{\ast }$ vertex from QCD sum rules

The form factor and the coupling constant in the ${\eta }_{b}B{B}^{\ast }$ vertex are evaluated in the framework of three-point QCD sum rules. The correlation functions responsible for the vertex is evaluated considering contributions of both $B$ and $B^{\ast }$ mesons as off-shell states. The form factors obtained are different for the two cases, whereas the final results of the coupling constant are compatible.