Lowest-Lying Scalar Mesons and a Possible Probe of Their Quark Substructure

Abstract

In this talk, an overview of the status of the light scalar mesons in the context of the non linear chiral Lagrangian of references [1-3] is presented. The evidence for the existence of a scalar nonet below 1 GeV is reviewed, and it is shown that by introducing a scalar nonet an indirect way of probing the quark substructure of these scalars through the scalar mixing angle can be obtained. It is then reviewed that consistency of this non-linear chiral Lagrangian framework with the experimental data on pi pi and pi K scattering, as well as the decay eta' to eta pi pi, results in a range for the mixing angle which indicates that the quark substructure of these light scalars are closer to a four quark picture.