Chiral Symmetry Restoration and the sigma-meson

Abstract

The sigma-meson, which is at best a broad resonance in the vacuum, may suffer a substantial red-shift and appear as a soft and narrow collective mode at finite temperature and baryon densities. The physics behind this softening phenomena and its relation to the partial restoration of chiral symmetry are discussed. Possible experiments in laboratory to test the idea are also summarized.

Comments: 7 pages, 3 figures, Invited talk at the International Workshop on ``Possible Existence of the Light $\sigma$ Resonance and its Implication to Hadron Physics'', (June 11-14, 2000, Yukawa Institute for Theoretical Physics, Kyoto, Japan)