Properties of the tensor state bc(b)over-bar(c)over-bar

Abstract

Spectroscopic parameters and decays of the exotic tensor meson T with content bc (b) over bar(c) over bar are explored in the context of the diquark-antidiquark model. We treat it as a state built of axial-vector diquark b(T)C gamma(mu)c and antidiquark (b) over bar gamma C-nu (c) over bar (T), where C is the charge conjugation matrix. The mass m and current coupling Lambda of this tetraquark are extracted from two-point sum rules. Our result for m = (12.70 +/- 0.09) GeV proves that T is unstable against strong dissociations to two-meson final states. Its dominant decay channels are processes T -> J/psi Upsilon, eta(b)eta(c), and B-c(()*()+) B-c(()*()-). Kinematically allowed transformations of T include also decays T -> D-(*()+) D-(*()-) and D-(*()0)(D) over bar (()*()0), which are generated by b (b) over bar annihilation inside of T. The full width of T is estimated by considering all of these channels. Their partial widths are calculated by invoking methods of three-point sum rule approach, which are required to evaluate strong couplings at corresponding tetraquark-meson-meson vertices. Our predictions for the mass and width Gamma(T) = (117.4 +/- 15.9) MeV of the tensor state T provide useful information for experimental studies of fully heavy four-quark exotic structures.