Riddle of the scalars: where is the sigma?

Abstract

The riddle of the sigma is recast in a way that tries to differentiate fact from fiction as a basis for future/further discussion. By doing this, it is hoped that the role of the sigma as dominating the ubiquitous $\pi \pi$ interactions below 1 GeV and its relation to the QCD vacuum can be clarified.

Comments: 20 pages, 12 figures Talk at the Workshop on Hadron Spectroscopy, WHS99, Frascati, March 1999. Revised version has the word "triangles" replaced by "circles"!