Interplay between kaon condensation and hyperons in high density matter(Hadrons at finite density) (original) (raw)
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Interplay between kaon condensation and hyperons in highly dense matter
Physical Review C, 2008
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.
Effects of three-baryon forces on kaon condensation in hyperon-mixed matter
Physics Letters B, 2021
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.
Role of Weak Interaction on Kaon Condensation in Neutron Matter: A Result with Hyperon Excitations
Progress of Theoretical Physics, 1993
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 ..
Kaonic modes in hyperonic matter and p-wave kaon condensation
Nuclear Physics A, 2002
Kaon excitations (kaonic modes) are investigated in hyperonic matter, where hyperons (Λ, Σ − , Ξ −) are mixed in the ground state of neutron-star matter. P-wave kaon-baryon interactions as well as the s-wave interactions are taken into account within chiral effective Lagrangian, and the nonrelativistic effective baryon-baryon interactions are incorporated. When the hyperon Λ is more abundant than the proton at high baryon density, a proton-particle-Λ-hole mode, which has the K + quantum number, appears in addition to other particle-hole modes with the K − quantum number. It is shown that the system becomes unstable with respect to a spontaneous creation of a pair of the particle-hole modes with K + and K − quantum numbers, stemming from the p-wave kaon-baryon interaction. The onset density of this p-wave kaon condensation may be lower than that of the s-wave K − condensation.
Kaon Condensation and Hyperon Mixture in Inhomogeneous Neutron Star Matter
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 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.
Kaon-condensed hypernuclei as highly dense self-bound objects
Nuclear Physics A, 2008
The structure of K −-condensed hypernuclei, which may be produced in the laboratory in strangeness-conserving processes, is investigated using an effective chiral Lagrangian for the kaon-baryon interaction, combined with a nonrelativistic baryon-baryon interaction model. It is shown that a large number of negative strangeness is needed for the formation of highly dense and deeply bound state with kaon condensates and that part of the strangeness should be carried by hyperons mixed in the nucleus. The properties of kaon-condensed hypernuclei such as the ground state energy and particle composition are discussed. Such a self-bound object has a long lifetime and may decay only through weak interaction processes. Comparison with other possible nuclear states is also made, such as kaon-condensed nuclei without mixing of hyperons and noncondensed multistrange hypernuclei. Implications of kaon-condensed hypernuclei for experiments are mentioned.
Physics Letters B, 1997
The variation of kaon mass in dense, charge-neutral baryonic matter at betaequilibrium has been investigated. The baryon interaction has been included by means of nonlinear Walecka model, with and without hyperons and the interaction of kaons with the baryons has been incorporated through the Nelson-Kaplan model. A selfconsistant, one-loop level calculation has been carried out. We find that at the mean field level, the presence of the hyperons makes the density-dependence of the kaon mass softer. Thus, the kaon condensation threshold is pushed up in the baryon density. The loop diagrams tend to lower the kaon condensation point for lower values of a 3 m s. We also find that the S-wave kaon-nucleon interaction plays the dominant role in determining the onset of kaon condensation and the contribution of the P-wave interaction is insignificant.
Density dependent hadron field theory for neutron stars with antikaon condensates
Physical Review C, 2002
We investigate K − andK 0 condensation in β-equilibrated hyperonic matter within a density dependent hadron field theoretical model. In this model, baryon-baryon and (anti)kaon-baryon interactions are mediated by the exchange of mesons. Density dependent meson-baryon coupling constants are obtained from microscopic Dirac Brueckner calculations using Groningen and Bonn A nucleon-nucleon potential. It is found that the threshold of antikaon condensation is not only sensitive to the equation of state but also to antikaon optical potential depth. Only for large values of antikaon optical potential depth, K − condensation sets in even in the presence of negatively charged hyperons. The threshold ofK 0 condensation is always reached after K − condensation. Antikaon condensation makes the equation of state softer thus resulting in smaller maximum mass stars compared with the case without any condensate. PACS: 26.60.+c, 21.65.+f, 97.60.Jd, 95.30.Cq
Phase transitions and behavior of kaons in hot and dense matter
AIP Conference Proceedings, 2005
We study phase transitions and the behavior of kaons in hot and dense matter, giving special attention to the role of strange quarks. At T = 0, it is found that the fraction of the strange valence quarks affects the energy per particle of the system, without changing the nature of the phase transition, and, on the other side, it has meaningful effects on the behavior of kaons and antikaons masses. The phase behavior of kaons in the T − ρ plane is analyzed in connection with the chiral phase transition.
Negative kaons in dense baryonic matter
Physical Review C, 2003
The kaon polarization operator in dense baryonic matter of arbitrary isotopic composition is calculated including s-and p-wave kaon-baryon interactions. The regular part of the polarization operator is extracted from the realistic kaon-nucleon interaction based on the chiral and 1/N c expansion. Contributions of ⌳(1116), ⌺(1195), ⌺*(1385) resonances are taken explicitly into account in the pole and regular terms with the inclusion of mean-field potentials. The baryon-baryon correlations are incorporated and fluctuation contributions are estimated. Results are applied for K Ϫ in neutron star matter. Within our model a second-order phase transition to the s-wave K Ϫ condensate state occurs at c տ4 0 with baryon-baryon correlations included. We show that a second-order phase transition to the p-wave K Ϫ condensate state may occur at densities c ϳ(3 -5) 0 dependent on the parameter choice. We demonstrate that a first-order phase transition to a protonenriched ͑approximately isospin-symmetric͒ nucleon matter with a p-wave K Ϫ condensate can occur at smaller densities, Շ2 0 . The transition is accompanied by the suppression of hyperon concentrations.