Exotic open-flavor bc(q)over-bar(q)over-bar, bc(s)over-bar(s)over-bar and qc(q)over-bar(b)over-bar, sc(s)over-bar(b)over-bar tetraquark states

We study the exotic bc (q) over bar(q) over bar, bc (s) over bar(s) over bar and qc (q) over bar(b) over bar, sc (s) over bar(b) over bar 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 (q) over bar(q) over bar system and 7.2-7.3 GeV for the bc (s) over bar(s) over bar system. For the qc (q) over bar(b) over bar 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 (s) over bar(b) over bar states are 7.1 and 6.9-7.1 GeV, respectively. The tetraquark states qc (q) over bar(b) over bar and sc (s) over bar(b) over bar lie below the thresholds of (DB(*))-B-(*) and (DsBs(*))-B-(*) respectively, but they can decay into B-c plus a light meson. However, the tetraquark states bc (q) over bar(q) over bar and bc (s) over bar(s) over bar lie below the D-(*)(B) over bar ((*)) and D-s((*))(B) over bar ((*))(s) thresholds, suggesting dominantly weak decay mechanisms.