Tetraquarks, their Masses and Decays in QED_2

Recent observations by Belle and BESIII of charged quarkonium-like resonances give new stimulus for theoretical investigation of exotic hadrons in general and heavy tetraquarks in particular. We use QED_2, a confining theory, as a model for the masses and decays of tetraquarks. Here we discuss the states (Q Qbar q qbar) and (Q Q qbar qbar) (and its anti-particle), where Q and q are two fermion flavors with masses M and m, so that M > m. We then discuss decay modes of these states into (Q Qqbar), (q qbar), (Q qbar), (Qbar q). It turns out that (Q Qbar q qbar) is stable, while (Q Q qbar qbar) is not.