Exotic open-flavor $bc\bar{q}\bar{q}$, $bc\bar{s}\bar{s}$ and $qc\bar{q}\bar{b}$, $sc\bar{s}\bar{b}$ tetraquark states

Abstract

We study the exotic $bc\bar{q}\bar{q}$, $bc\bar{s}\bar{s}$ and $qc\bar{q}\bar{b}$, $sc\bar{s}\bar{b}$ systems by constructing the corresponding tetraquark currents with $J^P=0^{+}$ and $1^{+}$. After investigating the two-point correlation functions and the spectral densities, we perform QCD sum rule analysis and extract the masses of these open-flavor tetraquark states. Our results indicate that the masses of both the scalar and axial vector tetraquark states are about $7.1-7.2$ GeV for the $bc\bar{q}\bar{q}$ system and $7.2-7.3$ GeV for the $bc\bar{s}\bar{s}$ system. For the $qc\bar{q}\bar{b}$ tetraquark states with $J^P=0^{+}$ and $1^{+}$, their masses are extracted to be around $7.1$ GeV. The masses for the scalar and axial vector $sc\bar{s}\bar{b}$ states are $7.1$ GeV and $6.9-7.1$ GeV, respectively. The tetraquark states $qc\bar{q}\bar{b}$ and $sc\bar{s}\bar{b}$ lie below the thresholds of $D^{(\ast )}{B}^{(\ast )}$ and $D_s^{(\ast )}{B}_s^{(\ast )}$ respectively, but they can decay into $B_c$ plus a light meson. However, the tetraquark states $bc\bar{q}\bar{q}$ and $bc\bar{s}\bar{s}$ lie below the $D^{(\ast )}{\bar{B}}^{(\ast )}$ and $D_s^{(\ast )}{\bar{B}}_s^{(\ast )}$ thresholds, suggesting dominantly weak decay mechanisms.

Comments: 18 pages, 7 figures, 4 tables