Delayed Collapse of Protoneutron Stars with Kaon Condensate

Equation of state with kaon condensate is derived for isentropic and neutrino-trapped matter. Both are important ingredients to study the delayed collapse of protoneutron stars. Solving the TOV equation, we discuss the static properties of protoneutron stars and implications for their delayed collapse.Comment: 6 pages, to appear in Proceedings of PANIC9

Inhomogeneous Chiral Phase in Quark Matter

Recent development of inhomogeneous chiral phase in Kyoto group is briefly reviewed. First, the nesting effect of the Fermi surface is emphasized as a key mechanism leading to inhomogeneous chiral phase. After introduction of inhomogeneous chiral phase, some topological aspect is discussed in 1+1 dimensions and in the presence of the magnetic field in 1+3 dimensions. Spectral asymmetry gives rise to anomalous quark number and is closely related to chiral anomaly. It may induce spontaneous magnetization and a novel Lifshitz point may appear on the line $\mu=0$. Some astronomical implications are briefly discussed. Finally, the effects of the fluctuations around the order parameter are discussed; the propagator of the fluctuations exhibits a singularity at finite momentum and changes the properties of the phase transition through loop diagrams.Comment: 8 pages,3 figures, Proc. of QCS2017 (Kyoto, Japan

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

Magnetic instability of quark matter

Spontaneous magnetization of quark liquid is examined. It is pointed out that quark liquid has potential to be ferromagnetic at rather low densities.Comment: 7 page, 3 figure

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

Microscopic origin of the magnetic field in compact stars

A magnetic aspect of quark matter is studied by the Fermi liquid theory. The magnetic susceptibility is derived with the one-gluon-exchange interaction, and the critical Fermi momentum for spontaneous spin polarization is found to be 1.4fm^{-1}. A scenario about the origin of the magnetic field in compact stars is presented by using this result.Comment: 6pages,2figure

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