Doubly heavy tetraquark resonant states

Meng, Q.*; Harada, Masayasu*; Hiyama, Emiko; Hosaka, Atsushi; Oka, Makoto   

Spectrum of the doubly heavy tetraquarks, , is studied in a constituent quark model. Four-body problem is solved in a variational method where the real scaling technique is used to identify resonant states above the fall-apart decay thresholds. In addition to the two bound states that were reported in the previous study we have found several narrow resonant states above the and thresholds. Their structures are studied and are interpreted by the quark dynamics. A narrow resonance with spin-parity is found to be a mixed state of a compact tetraquark and a scattering state. This is driven by a strong color Coulombic attraction between the quarks. Negative-parity excited resonances with , and form a triplet under the heavy-quark spin symmetry. It turns out that they share a similar structure to the -mode of a singly heavy baryon as a result of the strongly attractive correlation for the doubly heavy diquark.