  The light scalar nonets are studied using the QCD sum rules for the
tetraquark operators. The operator product expansion for the correlators is
calculated up to dimension 12 and this enables us to perform analyses retaining
sufficient pole-dominance. To classify the light scalar nonets, we investigate
the dependence on current quark mass and flavor dynamics. Especially, to
examine the latter, we study separately SU(3) singlet and octet states, and
show that the number of annihilation diagrams is largely responsible for their
differences, which is also the case even after the inclusion of the finite
quark mass. Our results support the tetraquark picture for isosinglets, while
that for octets is not conclusive yet.
