B_c^+- decays into tetraquarks

Understand

The recent observation by the D0 collaboration of a narrow structure X(5568) consisting of four different quark flavors bdus, has not been confirmed by LHCb.

• More data and dedicated analyses are needed to cover a larger mass range.
• In the tightly bound diquark model, we estimate the lightest bdus, 0^+ tetraquark at a mass of about 5770 MeV, approximately 200 MeV above the reported X(5568), and just 7 MeV below the B Kbar threshold.
• The charged tetraquark is accompanied by I=1 and I=0 neutral partners almost degenerate in mass.