We discuss the stability of tetraquarks systems made of two heavy quarks and two heavy antiquarks, with a potential model whose linear part is inspired by string dynamics.
At variance with some recent or less recent claims, we do not find binding for the double-charmonium or double-bottomonium cases. The string dynamics is, however, more favorable for (bcb̄c̄), i.e., a charmonium-bottomonium compound.
Some comments are made on the diquark-antidiquark approximation for describing these structures.
This talk is based on the paper: arXiv:1703.00783, to appear in Phys. Rev D.