Open-charm tetraquark $$X_c$$Xc and open-bottom tetraquark $$X_b$$Xb

Motivated by the LHCb observation of exotic states $$X_{0,1}(2900)$$ with four open quark flavors in the $$D^- K^+$$ invariant mass distribution in the decay channel $$B^\pm \rightarrow D^+ D^- K^\pm $$ , we study the spectrum and decay properties of the open charm tetraquarks. Using the two-body chromomagnetic interactions, we find that the two newly observed states can be interpreted as a radial excited tetraquark with $$J^P=0^+$$ and an orbitally excited tetraquark with $$J^P=1^-$$ , respectively. We then explore the mass and decays of the other flavor-open tetraquarks made of $$su {\bar{d}} {\bar{c}}$$ and $$ d s {\bar{u}} {\bar{c}}$$ , which are in the $${\bar{6}}$$ or 15 representation of the flavor SU(3) group. We point that these two states can be found through the decays: $$X^{(\prime )}_{d s \bar{u}\bar{c}}\rightarrow (D^- K^-, D_s^- \pi ^-) $$ , and $$X^{(\prime )}_{s u \bar{d}\bar{c}}\rightarrow D_s^-\pi ^+ $$ . We also apply our analysis to open bottom tetraquark $$X_b$$ and predict their masses. The open-flavored $$X_b$$ can be discovered through the following decays: $$X_{ud{\bar{s}}\bar{b}}\rightarrow B^0K^+$$ , $$X^{(\prime )}_{d s \bar{u}\bar{b}}\rightarrow (B^0 K^-, B_s^0 \pi ^-) $$ , and $$X^{(\prime )}_{s u \bar{d}\bar{b}}\rightarrow B_s^0\pi ^+ $$ .