SCALAR MESONS AND LOW-MASS SIGMA: DOES THE σ REVEAL THE CONFINEMENT SINGULARITY?

Abstract

We present a short review of the current understanding of the scalar meson sector, with special attention to the problem of the low-mass σ. The dispersion relation N/D-method used for the restoration of the low-energy ππ (IJ PC = 00++)-wave amplitude is discussed. The low-energy ππ amplitude was determined from the data in the energy region 280–500 MeV and it was sewn with the previously found K-matrix solution for the region 450–1950 MeV. The N/D-amplitude has a pole on the second sheet of the complex-s plane, near the ππ threshold at [Formula: see text], that corresponds to the low-mass σ-meson. We discuss the hypothesis that this pole may be related to the confinement forces, thus being the eyewitness of confinement.