Chiral symmetry restoration in σ-meson production in hadronic processes

Abstract

Some puzzles about the nature and properties of the lightest scalar meson, σ or f0(500), are analyzed in the paper. We studied the σ-meson production both in N + N, N + d, etc., collisions and also in J/ψ, ψ(2S), ψ(3S), Υ(2S), etc., two-pion decays. The fundamental distinctions between the basic σ-meson parameters found in various hadronic processes can be explained most naturally by the chiral symmetry restoration in intermediate excited hadronic resonances. In the present paper we discuss some important aspects of chiral symmetry restoration in hadronic processes with interrelation to the basic features of QCD.