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 experiments on $\phi$-radiative decays and from $D$ decays to light hadrons is discussed. How we may gain a more complete understanding of this vacuum sector is outlined.
Categories: hep-ph