2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/43670Some issues on the low-mass scalar mesons are discussed in relation to the chiral transition of QCD vacuum. The importance to explore the possible collective nature of the $σ$ meson is emphasized in association with the chiral properties of nuclear media.Corrected typosHigh Energy Physics - Phenomenologytext