Open-charm tetraquark Xc and open-bottom tetraquark Xb

Motivated by the LHCb observation of exotic states X-0,X-1(2900) with four open quark flavors in the D- K+ invariant mass distribution in the decay channel B-+/- -> D+ D- K-+/-, 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 (d) over bar(c) over bar and ds (u) over bar(c) over bar, which are in the (6) over bar or 15 representation of the flavor SU(3) group. We point that these two states can be found through the decays: X-ds (u) over bar(c) over bar ((')) -> (D- K-, D-s(-) pi(-)), and X-su (d) over bar(c) over bar((')) -> 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 (s) over bar(b) over bar -> (BK+)-K-0, X-ds (u) over bar(b) over bar((')) -> ((BK-)-K-0, B-s(0) pi(-)), and X-su (d) over bar(b) over bar((')) -> B-s(0)pi(+).