A QCD sum rules calculation of the $\eta_c D^* D$ and $\eta_c D_s^* D_s$ form factors and strong coupling constants

TL;DR

This paper employs QCD sum rules to calculate the strong coupling constants of specific meson vertices involving $ ext{eta}_c$, $D^*$, $D$, $D_s^*$, and $D_s$, considering both perturbative and non-perturbative effects.

Contribution

It provides new calculations of the $ ext{eta}_c D^* D$ and $ ext{eta}_c D_s^* D_s$ coupling constants using a three-point correlation function approach with off-shell mesons.

Findings

Calculated $g_{ ext{eta}_c D^* D} = 5.23^{+1.80}_{-1.38}$

Calculated $g_{ ext{eta}_c D_s^* D_s} = 5.55^{+1.29}_{-1.55}$

Included perturbative and non-perturbative contributions up to dimension five.

Abstract

We use the QCD sum rules for the three point correlation functions to compute the strong coupling constants of the meson vertices $\eta_c D^* D$ and $\eta_c D_s^* D_s$. We consider perturbative and non-perturbative contributions, working up to dimension five on the OPE. The vertices were studied considering that each one of its three mesons are off-shell alternately. The vertex coupling constant is evaluated through the extrapolation of the three different form factors. The results obtained for the coupling constants are $g_{\eta_c D^* D} = 5.23^{+1.80}_{-1.38}$ and $g_{\eta_c D_s^* D_s}=5.55^{+1.29}_{-1.55}$.