  The mixing angle, mass and couplings of the light scalar mesons $f_0(500)$
and $f_0(980)$ are calculated in the framework of QCD two-point sum rule
approach by assuming that they are tetraquarks with diquark-antidiquark
structures. The mesons are treated as mixtures of the heavy $|H\rangle
=([su][\bar s \bar u]+[sd][\bar s \bar d])/\sqrt 2$ and light $|L\rangle
=[ud][\bar u \bar d]$ scalar diquark-antidiquark components. We extract from
corresponding sum rules the mixing angles $\varphi_H$ and $\varphi_L$ of these
states and evaluate the masses and couplings of the particles $ f_0(500) $ and
$f_0(980)$.
