Scalars in the hadron world: the Higgs sector of the strong interaction

Abstract

Scalar mesons are a key expression of the strong physics regime of QCD and the role condensates, particularly $<q{\bar q}>$, play in breaking chiral symmetry. What new insights have been provided by recent experiments on $D, D_s$ and $J/ψ$ decays to light hadrons is discussed. We need to establish whether all the claimed scalars $σ$, $κ$, $f_0(1370)$, etc., really exist and with what parameters before we can meaningfully speculate further about which is transiently ${\bar q}q$, ${\bar{qq}} qq$, multi-meson molecule or largely glue.

10 pages, 4 figures. Invited talk at the International Conference on QCD and Hadronic Physics, Beijing, June 2005. A shortened version will appear in the Proceedings