Doubly heavy tetraquarks in a chiral-diquark picture

Energy spectrum of doubly heavy tetraquarks, $T_{QQ}$ ($QQ \bar{q} \bar{q}$ with $Q = c, b$ and $q u, d, s$), is studied in the potential chiral-diquark model. Using chiral effective theory diquarks quark-diquark-based model, $T_{bb}$, $T_{cc}$, $T_{cb}$ tetraquarks are described as a three-body system composed two quarks an antidiquark. We find several $T_{bb}$ bound states, while no $T_{cc}$ (deep) state seen. also study change tetraquark masses under restoration symmetry.