Pseudoscalar and vector tetraquarks $bb\overline{c}\overline{c}$

Abstract

The pseudoscalar and vector four-quark states $bb\overline{c}\overline{c}$ are studied in the context of the QCD sum rule method. We model $T_{\mathrm{ \ \ PS}} $ and $T_{\mathrm{V}}$ as structures built of diquarks $ b^{T}C\gamma_{5}b$, $\overline{c}C\overline{c}^{T}$ and $b^{T}C\gamma _{5}b$ , $\overline{c}C\gamma_{\mu}\gamma_{5}\overline{c}^{T}$, respectively, with $ C$ being the charge conjugation matrix. The spectroscopic parameters of the tetraquarks $T_{\mathrm{PS}}$ and $T_{\mathrm{V}}$, i.e., their masses and current couplings are calculated using QCD two-point sum rule method. We evaluate the full widths of $T_{\mathrm{PS}}$ and $T_{\mathrm{V}}$ by taking into account their kinematically allowed decay channels. In the case of the pseudoscalar particle they are processes $T_{\mathrm{PS}} \to B_{c}^{-}B_{c}^{\ast -}$, $B_{c}^{-}B_{c}^{-}(1^{3}P_{0})$ and $B_{c}^{\ast -}B_{c}^{-}(1^{1}P_{1})$. The vector state $T_{\mathrm{V}}$ can dissociate to meson pairs $2 B_{c}^{-}$, $2 B_{c}^{\ast -}$ and $ B_{c}^{-}B_{c}^{-}(1^{1}P_{1})$. Partial widths of these decays are determined by the strong couplings at relevant tetraquark-meson-meson vertices, which evaluated in the context of the three-point sum rule approach. Predictions obtained for the mass and full width of the pseudoscalar $m =(13.092\pm 0.095)~\mathrm{GeV}$, $\Gamma _{\mathrm{PS} }=(63.7\pm 13.0)~\mathrm{MeV}$ and vector $\widetilde{m} =(13.15\pm 0.10)~ \mathrm{GeV}$, $\Gamma_{\mathrm{V}}=(53.5\pm 10.3)~\mathrm{MeV}$ tetraquarks can be useful for analyses of different four-quark resonances.