QCD sum rules study of $QQ-\bar{u}\bar{d}$ mesons

Abstract

We use QCD sum rules to study the possible existence of $QQ-\bar{u}\bar{d}$ mesons, assumed to be a state with $J^P=1^{+}$. For definiteness, we work with a current with an axial heavy diquark and a scalar light antidiquark, at leading order in ${\alpha }_s$. We consider the contributions of condensates up to dimension eight. For the $b$-quark, we predict $M_{T_{bb}}=(10.2\pm 0.3)\mathrm{GeV}$, which is below the $\bar{B}{\bar{B}}^{\ast }$ threshold. For the $c$-quark, we predict $M_{T_{cc}}=(4.0\pm 0.2)\mathrm{GeV}$, in agreement with quark model predictions.

Comments: replaced version accepted for publication to Phys. Lett. B