Chiral Dynamics of scalar mesons: radiative $\varphi$ decay and $\sigma$ in the medium through ${\pi }^0{\pi }^0$ nuclear photoproduction

Abstract

In order to assess the relevance of chiral dynamics in the scalar sector we address two recent problems: radiative decay of the $\varphi$, for which there are quite recent data from Frascati, and the modification of the $\sigma$ properties in the nuclear medium seen through the ${\pi }^0{\pi }^0$ photoproduction in nuclei.

Comments: Talk given at the High Energy Physics Workshop "Scalar Mesons: an Interesting Puzzle for QCD", Utica, New York, May 2003