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Register a new userJ/psi D*D* vertex from QCD sum rules
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We calculated the strong form factor and coupling constant for the $J/psi D^* D^*$ vertex in a QCD sum rule calculation. We performed a double Borel sum rule for the three point correlation function of vertex considering both $J/psi$ and $D^*$ mesons off--shell. The form factors obtained are very different, but they give the same coupling constant.
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We calculate the form factors and the coupling constant in the $D^{*}D rho $ vertex in the framework of QCD sum rules. We evaluate the three point correlation functions of the vertex considering both $ D $ and $ rho $ mesons off--shell. The form factors obtained are very different but give the same coupling constant: $g_{D^{*}D rho} = 4.1 pm 0.1$ GeV$^{-1}$.
We calculate the form factors and the coupling constant in the $rho D^* D^*$ vertex in the framework of QCD sum rules. We evaluate the three point correlation functions of the vertex considering both $rho$ and $D^*$ mesons off--shell. The form factors obtained are very different but give the same coupling constant: $g_{rho D^* D^*} = 6.6 pm 0.31$. This number is 50% larger than what we would expect from SU(4) estimates.
We derive new QCD sum rules for $Bto D$ and $Bto D^*$ form factors. The underlying correlation functions are expanded near the light-cone in terms of $B$-meson distribution amplitudes defined in HQET, whereas the $c$-quark mass is kept finite. The leading-order contributions of two- and three-particle distribution amplitudes are taken into account. From the resulting light-cone sum rules we calculate all $Bto Dst $ form factors in the region of small momentum transfer (maximal recoil). In the infinite heavy-quark mass limit the sum rules reduce to a single expression for the Isgur-Wise function. We compare our predictions with the form factors extracted from experimental $Bto Dst l u_l$ decay rates fitted to dispersive parameterizations.
The $H^*Hpi$ form factor for H = B and D mesons is evaluated in a QCD sum rule calculation. We study the Borel sum rule for the three point function of two pseudoscalar and one vector meson currents up to order four in the operator product expansion. The double Borel transform is performed with respect to the heavy meson momenta. We discuss the momentum dependence of the form factors and two different approaches to extract the $H^*Hpi$ coupling constant.
Motivated by recent interest in soft $J/Psi$ production in B decays, we investigate ${B}^0 to J/Psi D^{(star)}$ and $eta_c D^{(star)}$ decays in perturbative QCD. We find that, within that framework, these decays are calculable since the heavy $cbar{c}$ pair in the final states is created by a hard gluon. The branching ratios are estimated to be around $10^{-7}sim 10^{-8}$, too small to be consistent with the data, suggesting that other mechanism(s) contribute to the observed excess of soft $J/Psi$ in ${B}^0 to J/Psi + X$ decays. The possibility of the production of a hybrid $s{bar d}g$ meson with mass about 2 GeV is briefly entertained.
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