Chiral Structure of Scalar and Pseudoscalar Mesons

We systematically study the chiral structure of local tetraquark currents of flavor singlet and J(P)=0(+). We also investigate their chiral partners, including scalar and pseudoscalar tetraquark currents of flavor singlet, octet, 10, 10_bar and 27. We study their chiral transformation properties. Particularly, we use the tetraquark currents belonging to the "non-exotic" [(3_bar,3)+(3,3_bar)] chiral multiplets to calculate the masses of light scalar mesons through QCD sum rule. The two-point correlation functions are calculated including all terms and only the connected parts. The results are consistent with the experimental values.