Related papers: Chiral Transition and Some Issues on the Scalar Me…
It is pointed out that the hadron spectroscopy should be a study of the structure of the QCD vacuum, low-energy elementary excitations on top of which are hadrons. Concentrating on the dynamical breaking of the chiral symmetry in the QCD…
We review recent developments in exploring possible precursory phenomena of partial restoration of chiral symmetry in nuclear medium by examining the spectral function in the scalar channel. We emphasize that the wave function…
We discuss how the possible changes of hadron properties can be tested, associated with the chiral transition in nuclear medium; the hadrons discussed are the vector mesons,the $\sigma$ meson and the chiral partner of the nucleon. We…
We give a brief survey on the physical significance of the low-mass scalar mesons in QCD, and also report on recent lattice studies on the sigma and kappa mesons. The importance to explore the in-medium properties of the hadrons is…
After giving brief discussions on the chiral condensate in hot and/or dense hadronic matter and the significance of the $\sigma$ meson in QCD, we discuss the importance of experiments using nuclear targets including ones with…
After giving a short introduction to the Nambu-Jona-Lasinio model with an anomaly term, we show the importance of the scalar-scalar correlation in the low-energy hadron dynamics, which correlation may be summarized by a scalar-isoscalar…
In order to assess the relevance of chiral dynamics in the scalar sector we address two recent problems: radiative decay of the $\phi$, for which there are quite recent data from Frascati, and the modification of the $\sigma$ properties in…
After showing the characteristic features of the chiral transition in QCD at finite temperature $T$, we note the significance of the sigma-mesonic mode in the chiral transition : Sigma meson may be regarded as the "Higgs particle" in QCD,…
The medium modification of mesons in dense hadronic matter is discussed with a focus on the relationship to the chiral structure of the non-perturbative QCD vacuum.
We discuss scalar mesons properties on the light of chiral dynamics. Considering them as the chiral partners of pseudo-scalar mesons we propose an explanation to their unusual properties based on non-trivial vacuum effects coming from the…
First, it is pointed out that hadron/nuclear physics based on QCD should be regarded as ``condensed matter physics'' of the QCD vacuum. We indicate that phase shift analyses which respect chiral symmetry (ChS), analyticity and crossing…
It should be a typical subject in this workshop to explore possible change of hadron properties in association with that of QCD vacuum due to an environmental change. In this report, we first summarize what hadrons are expected to show such…
We discuss a relativistic chiral theory of nuclear matter with $\sigma$ and $\omega$ exchange using a formulation of the $\sigma$ model in which all the chiral constraints are automatically fulfilled. We establish a relation between the…
It is the purpose of the present manuscript to emphasize those aspects that make the scalar sector with vacuum quantum numbers rather unique. Chiral symmetry is the basic tool for our study together with a resummation of Chiral Perturbation…
The origin of the lightest scalar mesons is studied in the framework of instanton liquid model (ILM) of the QCD vacuum. The impact of vacuum excitations on the sigma-meson features is analyzed in detail. In particular, it is noticed that…
After a brief overview of the realization of chiral symmetry in hot and/or dense medium, the implications of the existence of a light scalar-isoscalar meson (which we call $\sigma$ throughout this report) are discussed in the vacuum and in…
Some topics are introduced on possible evidences of chiral restoration in nuclei and related ones. The topics include the $\sigma$-mesonic mode in nuclei, the vector mesons in a nuclear matter, deeply bound pionic and Kaonic nuclei with a…
We analyze (using a chiral effective Lagrangian model) the scalar and pseudoscalar meson mass spectrum of QCD at finite temperature, above the chiral transition at $T_c$, looking, in particular, for signatures of a possible breaking of the…
A survey is given on selected topics concerning the role of spontaneous chiral symmetry breaking in low-energy QCD, and its dynamical implications for nuclear systems. This includes aspects of chiral thermodynamics (the temperature and…
We show that the non-strange scalar $\sigma$ meson, as now reported in the 1996 PDG tables, is a natural consequence of crossing symmetry as well as chiral dynamics for both strong interaction low energy $\pi\pi$ scattering and also $K \to…