The dynamical diquark model assumes that exotic hadrons can be formed from colored diquarks. This model asserts a multiquark exotic state composed of a compact diquark $\delta$ and antidiquark $\bar{ \delta}$ for a tetraquark interacting through a gluonic field of finite extent. Using Born-Oppenheimer (BO) approximation and BO potential calculated numerically on the lattice, we study mass spectra of $S-$wave $cc\bar{ b}\bar{ b}$, $bc\bar{ c}\bar{ c}$, and $bc\bar{ b}\bar{ b}$ tetraquark systems in the basis of diquark spins. We assume that colour-antitriple diquark and colour-triplet antidiquark form tetraquark state. The predicted mass spectrum for ground state of $cc\bar{ b}\bar{ b}$ is found to be lower then their corresponding two-meson thresholds. This system may be a candidate for bound state. Masses of $bc\bar{ c}\bar{ c}$ and $bc\bar{ b}\bar{ b}$ tetraquark states are found to be above than the corresponding two-meson thresholds.
Categories: hep-ph hep-ex