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Multidimensional structure of chiral crystals in quark matter

Lee, T.-G.*; 安武 伸俊*; 丸山 敏毅; 巽 敏隆*

Proceedings of Science (Internet), 8 Pages, 2017/05

We discuss the possibility of a multidimensional structure of inhomogeneous chiral condensates, which might be realized in cold and dense quark matter or the core of compact stars. For one-dimensional structures, the system becomes unstable at finite temperature due to the Landau-Peierls instability attributed to the excitation of the Nambu-Goldstone modes, with the result that there is no long-range order, while quasi-long-range order is realized instead. On the other hand, chirally inhomogeneous phases with two- or three-dimensional modulations may be realized as a true long-range ordered phase at any temperature, as inferred from the Landau-Peierls theorem. We here consider possible strategies to explore a multidimensional structure of chiral crystals.


Kaon condensation in hyperonic matter and equation of state

武藤 巧*; 丸山 敏毅; 巽 敏隆*

JPS Conference Proceedings (Internet), 14, p.020809_1 - 020809_3, 2017/02

Kaon condensation in hyperon-mixed matter, which may be realized in neutron stars, is investigated on the basis of the relativistic mean-field theory for baryon-baryon interaction, combined with the effective chiral Lagrangian. We introduce the range terms for both nucleons and hyperons and a pole contribution from the $$Lambda$$(1405) so as to reproduce the $$S$$-wave on-shell $$KN$$ scattering lengths. Onset density of kaon condensation in the hyperon-mixed matter and the equation of state (EOS) is obtained. It is shown that coexistence of kaon condensation and hyperon-mixed matter necessarily leads to significant softening of the EOS. We address stiffening effects to make the EOS consistent with recent observations of massive neutron stars.


Neutron star cooling with various superfluid and superconducting states

野田 常雄*; 橋本 正章*; 松尾 康秀*; 安武 伸俊*; 丸山 敏毅; 巽 敏隆*

JPS Conference Proceedings (Internet), 14, p.020805_1 - 020805_3, 2017/02

A neutron star is a highly dense object which lasts after a supernova explosion. The density of a neutron star overcomes the nuclear density, and the temperature is high at the beginning of its history. An isolated neutron star does not have any heat sources, and it cools down emitting thermal energy by neutrinos. The neutrino emission process depends on the state of interior matter of the neutron star. To compare theoretical simulations and observations of neutron stars, it can constrain the nuclear theory of high density region. We create a model of neutron stars with colour superconducting quark matter and nucleon super fluidity / superconductivity, to satisfy recent observations, including two 2$$M$$$$_odot$$ neutron stars. We parameterize these super-states and demonstrate the cooling curves, which show heavy stars do not always cool faster than lighter stars.


Multi-dimensional structure of crystalline chiral condensates in quark matter

Lee, T.-G.*; 西山 和也*; 安武 伸俊*; 丸山 敏毅; 巽 敏隆*

JPS Conference Proceedings (Internet), 14, p.020808_1 - 020808_3, 2017/02

We explore the multi-dimensional structure of inhomogeneous chiral condensates in quark matter. For a one-dimensional structure, the system becomes unstable at finite temperature due to the Nambu-Goldstone excitations. However, inhomogeneous chiral condensates with multi-dimensional modulations may be realized as a true long-range order at any temperature, as inferred from the Landau Peierls theorem. We here present some possible strategies for searching the multi-dimensional structure of chiral crystals.


Finite size effects in hadron-quark phase transition by the Dyson-Schwinger method

安武 伸俊*; Chen, H.*; 丸山 敏毅; 巽 敏隆*

Journal of Physics; Conference Series, 665(1), p.012068_1 - 012068_4, 2016/01

We study the hadron-quark phase transition, taking into account the finite-size effects for neutron star matter. For the hadron phase, we adopt a realistic equation of state within the framework of the Brueckner-Hartree-Fock theory. For the quark phase, we apply the Dyson-Schwinger method. The properties of the mixed phase are clarified by considering the finite-size effects. We find that, if the surface tension is strong enough, the equation of state becomes to be close the one with the Maxwell condition, though we properly adopt the Gibbs conditions. This result is qualitatively the same with the one by the use of the simple bag model. We also find that the mass-radius relation by the EoS is consistent with the observations of massive neutron stars.


Structure and properties of nuclear matter at the first-order phase transitions

丸山 敏毅

Acta Astronomica Sinica, 56(Suppl.), p.40 - 42, 2015/11



Cooling of compact stars with color superconducting quark matter

野田 常雄*; 安武 伸俊*; 橋本 正章*; 丸山 敏毅; 巽 敏隆*; 藤本 正行*

Acta Astronomica Sinica, 56(Suppl.), p.52 - 54, 2015/11

コンパクト星の冷却シナリオを示す。カシオペアA(Cas A)の観測により中央のソースは高い有効温度のコンパクト星で、エキゾチックな相を持たない場合の冷却と矛盾しない。Cas Aの観測データから、Cas Aの質量が太陽質量の1.5倍以上となることが分かる。それは重いコンパクト星ほど早く冷えるという現在のコンパクト星の冷却シナリオと矛盾する可能性がある。我々はコンパクト星の冷却にカラー超伝導のあるクォーク物質の効果を入れ、ギャップエネルギー$$Delta$$が10MeVより大きいと仮定した。冷却曲線を計算すると、重い星はゆっくり冷えて軽い星はその反対の傾向を持つことを示した。


Coexistence of kaon condensation and hyperons in hadronic matter and its relevance to quark matter

武藤 巧*; 丸山 敏毅; 巽 敏隆*

Acta Astronomica Sinica, 56(Suppl.), p.43 - 45, 2015/11



Quark-hadron phase transition with finite-size effects in neutron stars

安武 伸俊*; Benic, S.*; Blaschke, D.*; 丸山 敏毅; 巽 敏隆*

Acta Astronomica Sinica, 56(Suppl.), p.85 - 87, 2015/11



Interplay of antikaons with hyperons in nuclei and in neutron stars

武藤 巧*; 丸山 敏毅; 巽 敏隆*

EPJ Web of Conferences (Internet), 73, p.05007_1 - 05007_5, 2014/06




Finite-size effects at the hadron-quark transition and heavy hybrid stars

安武 伸俊*; Lastowiecki, R.*; Benic, S.*; Blaschke, D.*; 丸山 敏毅; 巽 敏隆*

Physical Review C, 89(6), p.065803_1 - 065803_10, 2014/06

 被引用回数:41 パーセンタイル:3.37(Physics, Nuclear)

We study the role of finite-size effects at the hadron-quark phase transition in a new hybrid equation of state constructed from an ab initio Br$"u$ckner-Hartree-Fock theory, with the realistic Bonn-B potential for the hadronic phase and a covariant nonlocal Nambu-Jona-Lasinio model for the quark phase. We construct static hybrid star sequences and find that our model can support stable hybrid stars with an onset of quark matter below $$2M_odot$$ and a maximum mass above $$2.17M_odot$$ in agreement with recent observations. If the finite-size effects are taken into account the core is composed of pure quark matter. Provided that the quark vector channel interaction is small and the finite size effects are taken into account, quark matter appears at densities 2-3 times the nuclear saturation density. In that case the proton fraction in the hadronic phase remains below the value required by the onset of the direct URCA process, so that the early onset of quark matter shall affect on the rapid cooling of the star.


Nuclear "pasta" structures in low-density nuclear matter and properties of the neutron-star crust

岡本 稔*; 丸山 敏毅; 矢花 一浩*; 巽 敏隆*

Physical Review C, 88(2), p.025801_1 - 025801_10, 2013/08

 被引用回数:23 パーセンタイル:12.57(Physics, Nuclear)



Shear oscillations in the hadron-quark mixed phase

祖谷 元*; 丸山 敏毅; 巽 敏隆*

Nuclear Physics A, 906, p.37 - 49, 2013/05

 被引用回数:8 パーセンタイル:38.03(Physics, Nuclear)



Cooling of compact stars with color superconducting phase in quark-hadron mixed phase

野田 常雄*; 橋本 正章*; 安武 伸俊*; 丸山 敏毅; 巽 敏隆*; 藤本 正行*

Astrophysical Journal, 765(1), p.1_1 - 1_5, 2013/03

 被引用回数:19 パーセンタイル:35.83(Astronomy & Astrophysics)

The Cas A observation shows that the central source is a compact star that has high effective temperature, and it is consistent with the cooling without exotic phases. The observation also gives the mass range of $$Mge 1.5M_odot$$, which may conflict with the current plausible cooling scenario of compact stars. There are some cooled compact stars such as Vela or 3C58, which can not be explained by the minimal cooling scenario with the neutrino emission by nucleon superfluidity (PBF). Then we invoke the exotic cooling processes where heavier stars cool faster than lighter ones. However, the result is inconsistent with the observation of Cas A. Therefore, we present a new cooling scenario by constructing models that include a quark color superconducting (CSC) phase with a large energy gap; this phase appears at ultrahigh density regions and reduces neutrino emissivity. In our model, a compact star has a CSC quark core with a low neutrino emissivity surrounded by high emissivity region made by normal quarks. Our result without considering nucleon superfluidity, shows that while heavier stars cool slowly and lighter ones quickly. Furthermore, we show that our scenario is consistent with the recent observations of the effective temperature of Cas A during the last 10 years, including nucleon superfluidity.


Thermodynamical description of hadron-quark phase transition and its implications on compact-star phenomena

安武 伸俊*; 野田 常雄*; 祖谷 元*; 丸山 敏毅; 巽 敏隆*

Recent Advances in Quarks Research, p.63 - 111, 2013/01

Using a baryon-baryon effective interaction for the hadron phase with hyperons and the MIT bag model for the quark phase, we derive the equation of state (EOS) of hadron-quark (HQ) matter, based on the Gibbs conditions for phase equilibrium. One of the interesting consequences may be the appearance of the inhomogeneous structures called "pasta", which are brought about by the balance between the surface and the Coulomb interactions. We explore the properties of cold catalyzed matter, hot matter and neutrino-trapped matter. The pasta structures become unstable by the charge screening of the Coulomb interaction, high temperatures or the neutrino trapping effect. HQ matter with pasta structures may affect astrophysical phenomena through its elasticity or thermal properties. We also discuss some implications on supernova explosion, the gravitational waves and the cooling of compact stars.


Amorphous state in the mixed phase of hadron-quark phase transition in protoneutron stars

安武 伸俊*; 丸山 敏毅; 巽 敏隆*

Physical Review D, 86(10), p.101302_1 - 101302_4, 2012/11

 被引用回数:6 パーセンタイル:70.89(Astronomy & Astrophysics)



Non-uniform structures in low-density nuclear matter and neutron star crust

岡本 稔; 丸山 敏毅; 矢花 一浩*; 巽 敏隆*

Proceedings of Science (Internet), 6 Pages, 2012/11

中性子星クラストや超新星爆発の前段階の低密度原子核物質において、「原子核パスタ」と呼ばれる非一様構造が現れると示唆されている。多くの先行研究において、一様背景電子と「原子核パスタ」の結晶構造が仮定され、Wigner-Seitz(WS) cell近似も使われてきた。球状の「原子核パスタ」(droplet)において、体心立方(bcc)格子が、面心立方(fcc)格子や単純立方格子よりエネルギー的に安定であるとされてきた。これは同等のサイズのdropletをそれぞれの結晶格子に配置した場合のクーロンエネルギーを比較することによって決定された。より正確には、電子の非一様性とdropletの結晶格子に応じたサイズを考慮しなければならない。われわれは相対論的平均場理論とThomas-Fermi模型に基づいてベータ平衡下の低密度原子核物質に対して空間3次元の計算を行った。発表では、エネルギー的に最も安定な構造、WS cell近似を用いた場合との比較、dropletのfccとbccにおける差異などについて述べる。また、中性子星クラスト物質の弾性率に対するdropletの有限サイズ効果や結晶構造の影響についても言及する。


Pasta structures in neutrino-degenerate nuclear matter

丸山 敏毅; 安武 伸俊*; 巽 敏隆*

Proceedings of Science (Internet), 6 Pages, 2012/11



Nuclear pasta in supernovae and neutron stars

渡辺 元太郎*; 丸山 敏毅

Neutron Star Crust, p.23 - 44, 2012/10



Mixed phases during the phase transitions

巽 敏隆*; 安武 伸俊*; 丸山 敏毅

Neutron Stars; The Aspect of High Density Matter, Equations of State and Observables, p.199 - 231, 2012/10


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