相关论文: Possible Production of the Sigma Meson in Nuclei
The QCD vacuum shows the dynamical breaking of chiral symmetry. In the hot/dense QCD medium, the chiral order parameter such as $ < \bar q q > $ is expected to change as function of temperature $T$ and density $\rho$ of the medium, and its…
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…
We first discuss the theoretical and phenomenological significance of the sigma meson ($\sigma$) in QCD. It is indicated that if the collective modes with the mass 500-600 MeV exists in the $I=J=0$ channel, various empirical facts in hadron…
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 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…
Recent topics on mesons in nuclei are discussed by especially emphasizing the role of the partial restoration of chiral symmetry in the nuclear medium. The spontaneously broken chiral symmetry in vacuum is considered to be incompletely…
In these lectures I first give a motivation for investigations of in-medium properties of hadrons. I discuss the relevant symmetries of QCD and how they might affect the observed hadron properties. I then discuss at length the observable…
The question of the origin of hadron masses is one major issue in the understanding of the strong interaction. The challenge is addressed by searching for indications of in-medium modifications of hadron properties and studying hadrons in…
The masses of hadrons in the vacuum, where the chiral symmetry is restored, and in the medium are in general different even when the changes in the order parameters of chiral symmetry are the same. Here, we first discuss the relation…
We study the modification of hadron masses due to the vacuum polarization using the chiral sigma model, which is extended to generate the $\omega$ meson mass by the sigma condensation in the vacuum in the same way as the nucleon mass. The…
The role of the quark condensate in low-energy QCD and its behaviour in nuclear matter are discussed. Partial restoration of chiral symmetry, as indicated by a reduction of the quark condensate in matter, could significantly alter the…
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…
Chiral symmetry is one of the most fundamental symmetries in QCD. It is closely connected to hadron properties in the nuclear medium via the reduction of the quark condensate <bar{q}q>, manifesting the partial restoration of chiral…
After decades-long attempts to measure the mass shift and understand the origin of hadron mass, it became clear that one has to analyze hadrons with small vacuum width. Also, to identify the effect of chiral symmetry breaking, one has to…
This review is devoted to the discussion of hadron properties in the nuclear medium and its relation to the partial restoration of chiral symmetry. Special attention is given to disentangle in-medium effects due to conventional many-body…
Recent theoretical developments of hadrons in nuclei are briefly reviewed in the aspect of chiral symmetry in nuclei. We show a general sum rule connecting in-medium hadronic quantities and quark condensate, emphasizing that both pionic…
It is widely believed that chiral symmetry is restored not only at high temperatures, but also at high nuclear densities. The drop of the order parameter of the chiral phase transition, the chiral condensate, with density has indeed been…
The role of chiral symmetry in nuclear physics is summarized. The topics treated are the chiral bag model for nucleon structure resulting from large $N_c$ QCD, the pion cloud in chiral perturbation theory for low-energy electroweak nuclear…
It is known that the decay process \eta\rightarrow\pi^0\pi^+\pi^- in free space is possible due to the isospin-symmetry breaking in Quantum Chromodynamics (QCD), i.e., the small mass difference between u and d quarks: The small width is…
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…