The light σ-meson

Light σ - Meson Production in Excited Υ Decay Processes

The results of analyses obtained in Part I are examined from the viewpoint of chiral symmetry. The mass spectra of ππ system are widely believed to be suppressed generally near the threshold, because of the derivative coupling property of Nambu-Goldstone π meson. However, this suppression does not hold in the processes with large energy release, and the steep increase from the ππ threshold obse...

Dynamical Properties of the σ Meson

Studies on the dynamical properties of the σ meson are reviewed and discussed. The important role of fundamental principles such as analyticity, unitarity and crossing symmetry played in the studies are stressed.

How to Parameterize a Light and Broad Resonance (the Σ Meson) * )

The evidence for the existence of a light and broad resonance in I=J=0 ππ scattering process – named as the σ resonance – has been accumulated, and more and more physicists working on the subject accepted the renaissance of the σ resonance. Among those works, model independent analysis 1), 2) are vital in clarifying the issue whether the σ resonance exists or not, since one has to distinguish a...

Symmetry - Breaking in a σ - Meson Plasma

In this brief paper we adress spontaneous symmetry breaking in a finite-temperature scalar meson plasma. We calculate the in-medium averaged thermal σ − σ scattering crossection and the related shear viscosity η(T) and mean-free-path L(T). Our results suggest that slightly below the critical temperature there is a 30 percent peak in the crossection leading to equivalent dips in η(T) and L(T). W...

π 0 γ and the role of σ - meson