A QCD sum rules calculation of the $J/\psi D_s^{\ast }{D}_s$ strong coupling constant

Abstract

In this work, we calculate the form factors and the coupling constant of the strange-charmed vertex $J/\psi D_s^{\ast }{D}_s$ in the framework of the QCD sum rules by studying their three-point correlation functions. All the possible off-shell cases are considered, $D_s$, $D_s^{\ast }$ and $J/\psi$, resulting in three different form factors. These form factors are extrapolated to the pole of their respective off-shell mesons, giving the same coupling constant for the process. Our final result for the $J/\psi D_s^{\ast }{D}_s$ coupling constant is $g_{J/\psi D_s^{\ast }{D}_s}=4.30_{-0.37}^{+0.42}{\text{GeV}}^{-1}$.

Comments: 17 pages, 4 figures