QCD sum rule study of the masses of light tetraquark scalar mesons

We study the low-lying scalar mesons of light u, d, s flavors in the QCD sum rule. Having all possible combinations of tetraquark currents in the local form, QCD sum rule analysis has been carefully performed. We found that using the appropriate tetraquark currents, the masses of σ, κ, f0 and a0 mesons appear in the region of 0.6-1 GeV with the expected ordering. The results are compared with that of the conventional q¯q currents, where the masses are considerably larger.