Pseudoscalar Mesons in Nuclear Medium

The behavior of pseudoscalar mesons in nuclear medium is reviewed with an emphasis on the possibility of their Bose-Einstein condensation in dense matter. In particular pion condensation is reexamined in detail, stimulated by recent theoretical and observational developments.Comment: Invited talk at the Workshop "MEDIUM02", Kyushu, Oct.25 - 26, 200

Ferromagnetism in QCD phase diagram

A possibility and properties of spontaneous magnetization in quark matter are investigated. Magnetic susceptibility is evaluated within Fermi liquid theory, taking into account of the screening effect of gluons. Spin wave in the polarized quark matter, as the Nambu-Goldstone mode, is formulated by way of the coherent-state path integral.Comment: 9pages,1 figure, Proc. of EXOCT 200

Magnetic aspects of QCD at finite density and temperature

Some magnetic aspects of QCD are discussed at finite density and temperature. Possibility of spontaneous magnetization is studied within Landau Fermi-liquid theory, and the important roles of the screening effects for gluon propagation are elucidated. Static screening for the longitudinal gluons improves the infrared singularities, while the transverse gluons receive only dynamic screening. The latter property gives rise to a novel non-Fermi-liquid behaviour for the magnetic susceptibility. Appearance of a density-wave state is also discussed in relation to chiral transition, where pseudoscalar condensate as well as scalar one takes a spatially non-uniform form in a chirally invariant way. Accordingly magnetization of quark matter oscillates like spin density wave. A hadron-quark continuity is suggested in this aspect, remembering pion condensation in hadronic phase.Comment: 6 pages, 8 figures, Proc. of INPN2010 to appear in J. Phy

Quark beta decay in an inhomogeneous chiral phase and cooling of hybrid stars

We discuss the cooling of hybrid stars by considering the neutrino emission from quark matter. As a current topic the appearance of various inhomogeneous chiral phases have been studied near the chiral transition. Here we consider the dual-chiral-density-wave (DCDW) specified by the spatially modulated quark condensates. Since the DCDW state can be represented as a chirally rotated state from the normal quark matter, the quark weak-current is accordingly transformed to have an additional phase factor which modifies the energy-momentum conservation at the vertex, and makes the quark direct Urca process possible. The direct evaluation of the neutrino emissivity shows that it is proportional to and the magnitude is comparable with the quark or pion cooling. Since the DCDW phase develops only in the limited density region, this novel mechanism may give an interesting scenario about cooling of hybrid stars that lower-mass stars should be cooler than higher-mass ones.Comment: 6 pages, 3 figures, Proc. of XII Int.Sympo. on Nuclei in the Cosmo

Protoneutron Stars with Kaon Condensation and their Delayed Collapse

Properties of protoneutron stars are discussed in the context of kaon condensation. Thermal and neutrino trapping effects are very important ingredients to study them. By solving the TOV equation, we discuss the static properties of protoneutron stars and the possibility of the delayed collapse during their evolution.Comment: 33pages,15 figures, accepted for publication in Nucl. Phys.

Magnetic Susceptibility of Quark Matter

Magnetic properties of quark matter is discussed by evaluating the spin susceptibility within Fermi-liquid theory. We take into account the dynamical and static screening effects. At finite temperature, an anomalous T^2 ln T term for susceptibity is shown as a non-Fermi-liquid effect due to the dynamical screening of transverse gluons.Comment: 4 pages, 2 figures, Proc. of YITP Symposium "Fundamental Problems in Hot and/or Dense QCD

How is chiral symmetry restored at finite density?

Taking into account pseudoscalar as well as scalar condensates, we reexamine the chiral restoration path on the chiral manifold. We shall see both condensates coherently produce a density wave at a certain density, which delays chiral restoration as density or temperature is increased.Comment: 4 pages, 2 figures; proc. of QM0