Takumi Muto - Academia.edu (original) (raw)
Papers by Takumi Muto
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2004
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2007
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2012
Soryushiron Kenkyu Electronics, 2006
Possible coexistence and/or competition of kaon condensation with hyperons are investigated in hy... more Possible coexistence and/or competition of kaon condensation with hyperons are investigated in hyperonic matter, where hyperons are mixed in the ground state of neutron-star matter. The formulation is based on the effective chiral Lagrangian for the kaon-baryon interaction and the nonrelativistic baryon-baryon interaction model. First, the onset condition of the s-wave kaon condensation realized from hyperonic matter is reexamined. It is shown that the usual assumption of the continuous phase transition is not always kept valid in the presence of the negatively charged hyperons (Σ −). Second, the equation of state (EOS) of the kaon-condensed phase in hyperonic matter is discussed. In the case of the stronger kaon-baryon attractive interaction, it is shown that a local energy minimum with respect to the baryon number density appears as a result of considerable softening of the EOS due to both kaon condensation and hyperon-mixing and recovering of the stiffness of the EOS at very high densities. This result implies a possible existence of self-bound objects with kaon condensates on any scale from an atomic nucleus to a neutron star.
Proceedings of the Workshop on Quarks and Compact Stars 2017 (QCS2017), 2018
We explore the structure and properties of matter in neutron stars, particularly at the densities... more We explore the structure and properties of matter in neutron stars, particularly at the densities where kaons and/or hyperons begin to mix in nucleons. The kaon mixture is expected to bring about regular structures, some of which are called "pasta". It is interesting to know what happens to the kaonic pasta if hyperons begin to mix into nucleons.
Progress of Theoretical Physics, 1993
Physics Letters B, 2021
Possibility of kaon-condensed phase in hyperon-mixed matter is considered on the basis of chiral ... more Possibility of kaon-condensed phase in hyperon-mixed matter is considered on the basis of chiral symmetry for kaon-baryon and kaon-kaon interactions, being combined with the relativistic mean-field theory for two-body baryon interaction. In addition, universal three-baryon repulsive force in the string-junction model and phenomenological three-nucleon attractive force are introduced. It is shown that softening of the equation of state stemming from both kaon condensation and mixing of hyperons is compensated with the repulsive effect of the three-baryon force and the relativistic effect for two-body baryon-baryon interaction. The latter effect reflects the density-dependence of scalar and vector meson mean-fields, which is constrained by the contribution of the attractive three-nucleon force to the binding energy at saturation density. The kaon-condensed phase in hyperon-mixed matter becomes stiff enough to be consistent with recent observations of massive neutron stars.
AIP Conference Proceedings, 2006
A self‐bound object, which is composed of hyperon‐mixed neutron‐star matter with kaon condensates... more A self‐bound object, which is composed of hyperon‐mixed neutron‐star matter with kaon condensates, is discussed as a candidate of baryonic dark matter. A kaon‐condensed nucleus is obtained in a liquid‐drop picture, and its relation to deeply bound kaonic nuclei is mentioned.
Nuclear Physics A, 1994
Abstract Kaon condensation and its implication in the cooling mechanism in neutron stars are inve... more Abstract Kaon condensation and its implication in the cooling mechanism in neutron stars are investigated within a framework of current algebra and PCAC. The weak interaction, n ⇌ p + K − , is shown to play a significant role in determining not only the critical density but also the equation of state of the K − condensed phase. The chemical equilibrium for the weak interaction leads to large proton-admixture. In connection with this result, the possibility of the direct URCA process, n → p + e − + v e , p + e − → n + v e , is investigated. It is shown that, within a simple treatment without the nuclear interactions such as the symmetry energy, the kinematical condition for the direct URCA process is not satisfied despite the large proton-mixing, due to the resulting small electron Fermi momentum. The physical content of the K − condensation from a viewpoint of strangeness degrees of freedom is also discussed.
Australian Journal of Physics, 1997
Relaxation in a kaon condensate proceeds through nonequilibrium weak reactions, which includes th... more Relaxation in a kaon condensate proceeds through nonequilibrium weak reactions, which includes the kaon-induced Urca and the modified Urca reactions. The kinetics of a K— condensate is considered semiclassically starting from a small seed of a condensate with the assumption that the system is in thermal equilibrium. It is shown that the temporal evolution to the K—condensed phase in the kinetic regime is divided into several characteristic time intervals as a result of the interplay between the two major weak processes. The implications for the dynamical evolution of newly-born neutron stars are briefly discussed.
Progress of Theoretical Physics Supplement, 2013
Effects of various hadron phases on thermal and dynamical properties of neutron stars are studied... more Effects of various hadron phases on thermal and dynamical properties of neutron stars are studied in connection with astronomical phenomena. In particular, nucleon superfiuidity and pion condensation are mainly considered. (1) It is shown that ALS solid core and rapid cooling in the presence of combined neutral and charged pion (7r 0 7rc)-condensed phase give the basis of an extended starquake model which explains both Vela and Crab pulsar glitches consistently. In this model, the neutron 1 So and 3 H superfiuids having different couplings with the crust are related to the observed two relaxation times. (2) Extra neutrino emissivity under the 7r 0 7rc•condensed phase is studied and each role of the 7r 0 and 7rc condensates is clarified. By the use of this emissivity, cooling history of pion-condensed neutron stars are discussed. (3) First order phase tninsition from the 7rc•condensed phase to the 7r 0 7rc one is shown to be essential to dynamical properties of pion-condensed neutron stars. Energy release associated with a mini-collapse is obtained in relation to the anomalous gamma-ray burst, where the dissipation mechanism in the pion-condensed phase is also discussed. (4) Characteristic features of hot and dense supernova matter are investigated and energy release of a hot neutron star at birth due to the first order phase transition to a cold pion-condensed neutron star is discussed in connection with the neutrino burst from the supernova SN1987 A. Also the extent of spin-up due to the contraction during the early cooling stage is estimated. (5) Maximum rotation rates of neutron stars with and without pion condensates are obtained, and it is shown that they serve as a probe for the existence of pion condensation in neutron stars.
Strangeness degree of freedom provides an important aspect for dense matter which may be realized... more Strangeness degree of freedom provides an important aspect for dense matter which may be realized in neutron stars and/or heavy ion collisions. Kaon condensation, a Bose-Einstein condensed
Progress of Theoretical Physics Supplement, 2004
The effects of kaon condensates on the equation of state (EOS) in hyperonic matter, where hyperon... more The effects of kaon condensates on the equation of state (EOS) in hyperonic matter, where hyperons (Λ, Σ −) are mixed in the ground state of neutron-star matter, are investigated. In the fully-developed phase of kaon condensation, it is shown that the EOS is much softened due to the s-wave kaon-baryon interactions as well as due to the hyperon-mixing. As a result, the energy of the system has a local minimum, which leads to a metastable self-bound kaoncondensed star in addition to a kaon-condensed star obtained by Maxwell's construction. The lifetime of the metastable state of the kaon-condensed bound star is estimated.
Progress of Theoretical Physics, 1993
Kcondensation in neutron matter is investigated by taking into account excitation of hyperons on ... more Kcondensation in neutron matter is investigated by taking into account excitation of hyperons on the basis of SU(3)L x SU(3)R chiral symmetry. It is shown that the weak interaction plays an important role for realization of Kcondensation, which largely affects an equation of state in its well-developed phase through the chemical equilibrium condition for the weak interaction process. Kcondensation of the s•wave type firstly appears at about three times the standard nuclear density. The chemical equilibrium for the weak interaction leads to increase of proton-mixing as the condensation proceeds. As a result of the large proton-mixing, the kaon chemical potential becomes negative. At a higher density, hyperon•mixing starts, and another phase transition, the Kcondensa• tion of the p-wave type, occurs. Implications of the K-condensed phase as an intermediate phase connecting normal hadronic matter with strange quark matter are briefly discussed ..
Physics Letters B, 1992
Some theoretical aspects of kaon condensation in neutron matter are considered on the basis of SU... more Some theoretical aspects of kaon condensation in neutron matter are considered on the basis of SU(3)LXSU(3) R current algebra and PCAC. It is clarified that the critical condition is different from charged pion condensation and the weak interaction plays a significant role near the threshold. The critical density lies around (3-4)no with the standard nuclear density no irrespective of the ambiguities of the ss content inside the nucleon. For comparison, K÷K-pair condensation in symmetric nuclear matter is also discussed.
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2004
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2007
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2012
Soryushiron Kenkyu Electronics, 2006
Possible coexistence and/or competition of kaon condensation with hyperons are investigated in hy... more Possible coexistence and/or competition of kaon condensation with hyperons are investigated in hyperonic matter, where hyperons are mixed in the ground state of neutron-star matter. The formulation is based on the effective chiral Lagrangian for the kaon-baryon interaction and the nonrelativistic baryon-baryon interaction model. First, the onset condition of the s-wave kaon condensation realized from hyperonic matter is reexamined. It is shown that the usual assumption of the continuous phase transition is not always kept valid in the presence of the negatively charged hyperons (Σ −). Second, the equation of state (EOS) of the kaon-condensed phase in hyperonic matter is discussed. In the case of the stronger kaon-baryon attractive interaction, it is shown that a local energy minimum with respect to the baryon number density appears as a result of considerable softening of the EOS due to both kaon condensation and hyperon-mixing and recovering of the stiffness of the EOS at very high densities. This result implies a possible existence of self-bound objects with kaon condensates on any scale from an atomic nucleus to a neutron star.
Proceedings of the Workshop on Quarks and Compact Stars 2017 (QCS2017), 2018
We explore the structure and properties of matter in neutron stars, particularly at the densities... more We explore the structure and properties of matter in neutron stars, particularly at the densities where kaons and/or hyperons begin to mix in nucleons. The kaon mixture is expected to bring about regular structures, some of which are called "pasta". It is interesting to know what happens to the kaonic pasta if hyperons begin to mix into nucleons.
Progress of Theoretical Physics, 1993
Physics Letters B, 2021
Possibility of kaon-condensed phase in hyperon-mixed matter is considered on the basis of chiral ... more Possibility of kaon-condensed phase in hyperon-mixed matter is considered on the basis of chiral symmetry for kaon-baryon and kaon-kaon interactions, being combined with the relativistic mean-field theory for two-body baryon interaction. In addition, universal three-baryon repulsive force in the string-junction model and phenomenological three-nucleon attractive force are introduced. It is shown that softening of the equation of state stemming from both kaon condensation and mixing of hyperons is compensated with the repulsive effect of the three-baryon force and the relativistic effect for two-body baryon-baryon interaction. The latter effect reflects the density-dependence of scalar and vector meson mean-fields, which is constrained by the contribution of the attractive three-nucleon force to the binding energy at saturation density. The kaon-condensed phase in hyperon-mixed matter becomes stiff enough to be consistent with recent observations of massive neutron stars.
AIP Conference Proceedings, 2006
A self‐bound object, which is composed of hyperon‐mixed neutron‐star matter with kaon condensates... more A self‐bound object, which is composed of hyperon‐mixed neutron‐star matter with kaon condensates, is discussed as a candidate of baryonic dark matter. A kaon‐condensed nucleus is obtained in a liquid‐drop picture, and its relation to deeply bound kaonic nuclei is mentioned.
Nuclear Physics A, 1994
Abstract Kaon condensation and its implication in the cooling mechanism in neutron stars are inve... more Abstract Kaon condensation and its implication in the cooling mechanism in neutron stars are investigated within a framework of current algebra and PCAC. The weak interaction, n ⇌ p + K − , is shown to play a significant role in determining not only the critical density but also the equation of state of the K − condensed phase. The chemical equilibrium for the weak interaction leads to large proton-admixture. In connection with this result, the possibility of the direct URCA process, n → p + e − + v e , p + e − → n + v e , is investigated. It is shown that, within a simple treatment without the nuclear interactions such as the symmetry energy, the kinematical condition for the direct URCA process is not satisfied despite the large proton-mixing, due to the resulting small electron Fermi momentum. The physical content of the K − condensation from a viewpoint of strangeness degrees of freedom is also discussed.
Australian Journal of Physics, 1997
Relaxation in a kaon condensate proceeds through nonequilibrium weak reactions, which includes th... more Relaxation in a kaon condensate proceeds through nonequilibrium weak reactions, which includes the kaon-induced Urca and the modified Urca reactions. The kinetics of a K— condensate is considered semiclassically starting from a small seed of a condensate with the assumption that the system is in thermal equilibrium. It is shown that the temporal evolution to the K—condensed phase in the kinetic regime is divided into several characteristic time intervals as a result of the interplay between the two major weak processes. The implications for the dynamical evolution of newly-born neutron stars are briefly discussed.
Progress of Theoretical Physics Supplement, 2013
Effects of various hadron phases on thermal and dynamical properties of neutron stars are studied... more Effects of various hadron phases on thermal and dynamical properties of neutron stars are studied in connection with astronomical phenomena. In particular, nucleon superfiuidity and pion condensation are mainly considered. (1) It is shown that ALS solid core and rapid cooling in the presence of combined neutral and charged pion (7r 0 7rc)-condensed phase give the basis of an extended starquake model which explains both Vela and Crab pulsar glitches consistently. In this model, the neutron 1 So and 3 H superfiuids having different couplings with the crust are related to the observed two relaxation times. (2) Extra neutrino emissivity under the 7r 0 7rc•condensed phase is studied and each role of the 7r 0 and 7rc condensates is clarified. By the use of this emissivity, cooling history of pion-condensed neutron stars are discussed. (3) First order phase tninsition from the 7rc•condensed phase to the 7r 0 7rc one is shown to be essential to dynamical properties of pion-condensed neutron stars. Energy release associated with a mini-collapse is obtained in relation to the anomalous gamma-ray burst, where the dissipation mechanism in the pion-condensed phase is also discussed. (4) Characteristic features of hot and dense supernova matter are investigated and energy release of a hot neutron star at birth due to the first order phase transition to a cold pion-condensed neutron star is discussed in connection with the neutrino burst from the supernova SN1987 A. Also the extent of spin-up due to the contraction during the early cooling stage is estimated. (5) Maximum rotation rates of neutron stars with and without pion condensates are obtained, and it is shown that they serve as a probe for the existence of pion condensation in neutron stars.
Strangeness degree of freedom provides an important aspect for dense matter which may be realized... more Strangeness degree of freedom provides an important aspect for dense matter which may be realized in neutron stars and/or heavy ion collisions. Kaon condensation, a Bose-Einstein condensed
Progress of Theoretical Physics Supplement, 2004
The effects of kaon condensates on the equation of state (EOS) in hyperonic matter, where hyperon... more The effects of kaon condensates on the equation of state (EOS) in hyperonic matter, where hyperons (Λ, Σ −) are mixed in the ground state of neutron-star matter, are investigated. In the fully-developed phase of kaon condensation, it is shown that the EOS is much softened due to the s-wave kaon-baryon interactions as well as due to the hyperon-mixing. As a result, the energy of the system has a local minimum, which leads to a metastable self-bound kaoncondensed star in addition to a kaon-condensed star obtained by Maxwell's construction. The lifetime of the metastable state of the kaon-condensed bound star is estimated.
Progress of Theoretical Physics, 1993
Kcondensation in neutron matter is investigated by taking into account excitation of hyperons on ... more Kcondensation in neutron matter is investigated by taking into account excitation of hyperons on the basis of SU(3)L x SU(3)R chiral symmetry. It is shown that the weak interaction plays an important role for realization of Kcondensation, which largely affects an equation of state in its well-developed phase through the chemical equilibrium condition for the weak interaction process. Kcondensation of the s•wave type firstly appears at about three times the standard nuclear density. The chemical equilibrium for the weak interaction leads to increase of proton-mixing as the condensation proceeds. As a result of the large proton-mixing, the kaon chemical potential becomes negative. At a higher density, hyperon•mixing starts, and another phase transition, the Kcondensa• tion of the p-wave type, occurs. Implications of the K-condensed phase as an intermediate phase connecting normal hadronic matter with strange quark matter are briefly discussed ..
Physics Letters B, 1992
Some theoretical aspects of kaon condensation in neutron matter are considered on the basis of SU... more Some theoretical aspects of kaon condensation in neutron matter are considered on the basis of SU(3)LXSU(3) R current algebra and PCAC. It is clarified that the critical condition is different from charged pion condensation and the weak interaction plays a significant role near the threshold. The critical density lies around (3-4)no with the standard nuclear density no irrespective of the ambiguities of the ss content inside the nucleon. For comparison, K÷K-pair condensation in symmetric nuclear matter is also discussed.