Phenomenology of Chiral Transition at High Temperature and Density

点击翻译按钮获取中文摘要

In the first year, we developed a new cut-off scheme for the Nambu-Jona-Lasinio (NJL) model. The scheme is based on the dispersion relation and applicable to the finite temperature (T) and density (rho) cases. We also give a foundation to the mean-field theory at finite temperature, on the basis of an inequality due to Feynman. We calculated the width of the sigma meson in the medium at finite T and rho in various kinematical conditions.In the next (final) year, we proposed several experiments to see the possible mass shift of the sigma meson in the medium at finite density. This is based on the observation that scalar and vector fields can mix at finite density. We also proposed to detect 2pi^0 to see the sigma meson.We examined the reason why the time-dependent phenomena in the superconductors may be described in the diffusive time-dependent Ginzburug equation in contrast with the chiral transition. This is due to the fact that the effective spatial dimension of the superconductors as described the BCS theory is one not three as in the NJL model. We also clarified that the saturation properties hence thestability of nuclei is due to chiral symmetry of QCD.