On the Quark and Gluon Substructure of the Sigma and other Scalar Mesons

Original · EN

Within the increasing experimental evidence of the existence of the I=0 scalar low mass and wide σmeson, we review the first analysis of its quark and gluon substructure from QCD spectral sum rules and some low-energy theorems. The present data favour equal components of uu+ dd and of gg in its wave function, which make the wide sigma and the narrow f₀(980) as η'-like particles. A coherent picture of the other I=0 scalar mesons spectra within this mixing scheme is shortly discussed. We also expect the a₀(980) to be the lowest isovector ud state, and the K*₀(1430) its ds partner.