Recent progress in understanding the strong physics regime of QCD is described. The role played by condensates, particularly $q{ \bar q}$, in breaking chiral symmetry and generating constituent masses for $u$ and $d$ quarks is reviewed. The influence this has on hadrons with vacuum quantum numbers is emphasised. What we know of this sector from recent data on $\phi$-radiative decays and from $D$ decays to light hadrons is discussed. The key to further understanding is comprehensive analyses of such data, including that planned for Hall D at Jefferson Laboratory.
Categories: hep-ph