Masses of light tetraquarks and scalar mesons in the relativistic quark   model
  Masses of the ground state light tetraquarks are dynamically calculated in the framework of the relativistic diquark-antidiquark picture. The internal structure of the diquark is taken into account by calculating the form factor of the diquark-gluon interaction in terms of the overlap integral of the diquark wave functions. It is found that scalar mesons with masses below 1 GeV: f_0(600) (\sigma), K^*_0(800) (\kappa), f_0(980) and a_0(980) agree well with the light tetraquark interpretation. 
D. Ebert, R. N. Faustov, V. O. Galkin