Semileptonic and nonleptonic decays of the axial-vector tetraquark $T_{bb;\overline{u}\overline{d}}^{-}$

Abstract

The semileptonic and nonleptonic decays of the double-beauty axial-vector tetraquark $T_{bb;\overline{u}\overline{d}}^{-}$ to a state ${\tilde{T}}_{bc;\overline{u}\overline{d}}^0$ (hereafter $T_{bb}^{-}$ and ${\tilde{T}}_{bc}^0$, respectively) are investigated in the context of the QCD sum rule method. The final-state tetraquark ${\tilde{T}}_{bc}^0$ is treated as an axial-vector particle built of a heavy axial-vector diquark $b^T{\gamma }_{\mu }Cc$ and light scalar antidiquark $\overline{u}C{\gamma }_5{\overline{d}}^T$. Its spectroscopic parameters are calculated using the two-points sum rules by taking into account contributions of quark, gluon and mixed condensates up to dimension $10$. We study the dominant semileptonic $T_{bb}^{-}\to {\tilde{T}}_{bc}^{0}l{\overline{\nu }}_l$ and nonleptonic decays $T_{bb}^{-}\to {\tilde{T}}_{bc}^{0}M$, where $M$ is one of the pseudoscalar mesons ${\pi }^{-},K^{-},D^{-}$ and $D_s^{-}$. The partial widths of these processes are computed in terms of weak form factors $G_i(q^2),i=1,2,3,4$, extracted by employing the QCD three-point sum rule approach. Predictions obtained for partial widths of considered decays are used to improve accuracy of theoretical predictions for full width and lifetime of the tetraquark $T_{bb}^{-}$, which are important for experimental exploration of this exotic meson.

Comments: 10 Pages, 2 Figures and 3 Tables