Instanton interpolating current for $σ$--tetraquark
Abstract
Description
We perform a QCD sum rule analysis for the light scalar meson $σ$ ($f_0(600)$) with a tetraquark current related to the instanton picture for QCD vacuum. We demonstrate that instanton current, including equal weights of scalar and pseudoscalar diquark-antidiquarks, leads to a strong cancelation between the contributions of high dimension operators in the operator product expansion (OPE). Furthermore, in the case of this current direct instanton contributions do not spoil the sum rules. Our calculation, obtained from the OPE up to dimension 10 operators, gives the mass of $σ$--meson around 780MeV.
11 pages, 7 figures, final version to be appeared in Phys. Lett. B
11 pages, 7 figures, final version to be appeared in Phys. Lett. B