Fully heavy asymmetric scalar tetraquarks

Abstract

The scalar tetraquarks T-b and T-c with asymmetric contents bbb(--)c and ccc(--)b are explored using the QCD sum rule method. These states are modeled as the diquark-antidiquarks composed of the axial-vector components. The masses and current couplings of T-b and T-c are calculated using the two-point sum rule approach. The predictions obtained for the masses of these four-quark mesons prove that they are unstable against the strong two-meson fall-apart decays to conventional mesons. In the case of the tetraquark T-b this is the decay T-b ->eta B-b(c)-. The processes T-c ->eta(c)B(c )(+)and J/psi B & lowast;(+) (c )are kinematically allowed decay modes of the tetraquark T-c. The widths of corresponding processes are evaluated by employing the QCD three-point sum rule approach which are necessary to estimate strong couplings at the tetraquark-meson-meson vertices of interest. The mass m=(15698 +/- 95) MeV and width Gamma[T-b]=(36.0 +/- 10.4)MeV of the tetraquark T-b as well as the parameters m=(9680 +/- 102) MeV and Gamma[T-c]=(54.7 +/- 12.6) MeV in the case of Tc provide useful information to search for and interpret new exotic states