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Transcript of Interplay of antikaons with hyperons in nuclei and in neutron stars Interplay of antikaons with...
Interplay of antikaons with hyperons in nuclei and in neutron stars
Interplay of antikaons with hyperons in nuclei and in neutron stars
13th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon (Pontificia Universita della Santa Croce, Rome, Sep.30 – Oct.4, 2013)
Takumi Muto (Chiba Inst. Tech.) collaborators : Toshiki Maruyama (JAEA) Toshitaka Tatsumi (Kyoto Univ.)
Parallel Session : Meson-Nucleon Systems 3
Multi-strangeness system in hadronic matter1. Introduction
Strange matter( u, d, s quark matter )
hyperonic matter(Λ, Σ, Ξ, ・・・in the ground state)
Kaon condensation
・ Coexistence of antikaons and hyperons
In neutron-stars
Softening of EOS
Kaonic nuclei [ Y.Akaishi and T.Yamazaki, Phys.Rev. C65 (2002) 044005. ]
Multi-Antikaonic Nuclei
In nuclei
・ Coexistence of antikaons and hyperons : difficult
relativistic mean-field theory (RMF)+coupled with effective chiral Lagrangian
[T. Muto, T. Maruyama and T. Tatsumi, Phys. Rev. C79, 035207 (2009). ]
[T. Muto, T. Maruyama and T. Tatsumi, Genshikaku Kenkyu 57 Supplement 3, 230(2013).]
Toward unified description based on the same Kaon-baryon(B), B-B interaction model.
A possible existence of antikaonic nuclear bound states with hyperon-mixing for finite nuclei
Both K- mesons and hyperons are taken into account together in a unified way for both finite nuclei and neutron stars within the same framework.
We consider interplay between antikaons and hyperons within the RMF framework coupled with the effective chiral Lagrangian:
Appearance of hyperons and onset of kaon condensation in β-equilibrated infinite matter (neutron stars)
2-1. Baryon-Baryon interaction
[ D. B. Kaplan and A. E. Nelson, Phys. Lett. B 175 (1986) 57. ]
2-2. interactions Nonlinear chiral effective Lagrangian
Meson fields (K± ) (nonlinear representation)
Condensate assumption(K- mesons are condensed in the lowest energy state)
Mesons:B =
Meson decay const.
2. Outline of the model
kaon fields (K± ) (nonlinear representation)
(scalar) (vector)
RMF
(scalar) (vector)
S-wave scalar int. S-wave vector int.
Kaonic part of the Lagrangian density
・ saturation properties of nuclear matter・ binding energy of nuclei and proton-mixing ratio・ density distributions of p and n
gross features of normal nuclei and nuclear matter
(ρ0 =0.153 fm− 3 )
2-3. Choice of parameters
--- NN interaction ---
--- vector meson couplings for Y --- SU(6) symmetry
--- scalar meson couplings for Y ---
repulsive case
--- scalar meson couplings for Kaon ---
at ρ0 in symmetric nuclear matter
Decay of f0(975)
quark and isospin counting rule
--- vector meson couplings for Kaon ---
UK- = (− 180 〜 − 80 ) MeV
K- optical potential depth :
SU(6) symmetry
|S|: the number of the embedded K-
Assume : Spherical symmetry
A = N + Z : mass number
Z: the number of protonMulti-K Nuclei
p
K-
r
ー
3. Coexistence of antikaons and hyperons in finite nuclei
Local density approximation for baryons
K- mesonhyperon
proton
neutron
[ Charge conservation ]
[ Baryon number conservation ]
[ Strangeness conservation ]
[ Initial target nucleus ]3-1. Outline
3-2. Thermodynamic potential
Chemical equilibrium for strong processes
as
Take into account of nonmesonic processes,
in addition to mesonic process,
Coexistence condition of antikaons with hyperons in finite nuclei
4 Numerical results
1. density distributions
For finite nuclei ( )
2. Stability of multi-strangeness nuclei
4 Numerical results
| UK | < 180 MeVA=15, Z=8 ( )No K- meson is bound.
4-1. density distributions
Ground state :
Central density ρρ
Multi-hypernuclei
Total energy Energy difference per unit of strangeness from normal nuclei ( |S| = 0 )
Strong decay of multi-hypernucleito
For |S| >3
| UK | < 180 MeV
4-2. Stability of multi-strangeness nuclei
5. Onset of kaon condensation in β-equilibrated matter (Neutron stars)
chemical equilibrium for weak processes
Onset of K- condensates
5-1 Onset of kaon condensation in hyperon matter
Appearance of antikaons with hyperons in finite nuclei
5-2 EOS in β-equilibrated matter
Energy/particle Particle fractions
We have considered a possible existence of kaonic bound nuclei with hyperon-mixing and kaon condensation in hyperonic matter In the same framework of the RMF coupled with nonlinear effective chiral Lagrangian for and interactions.
Ξ- -mixing becomes dominant for large|S|.
For moderate | UK- | (< 180 MeV), the ground state is given by multi-hypernuclei without bound K- mesons.
6 Summary and outlook
Finite effects of nucleiAntikaons do not receive much attraction
Finite nuclei
Effects of kaon condensates on EOSNeutron stars
K- -baryon attractive interactions, especially, the S-wave scalar attractions lead to additional softening of the EOS as compared with the case of hyperonic matter.
Strong repulsion between baryons andsuppression of attractive - baryon interactionat high densities are needed.
(1) ambiguity of S-wave K-Baryon interactions
Scalar int.: content in the nucleon is small.
[R. D. Young, A. W. Thomas, Nucl. Phys. A844(2010)266c.]
The soft EOS cannot support massive stars (~ 2 M).
(Recent Lattie QCD)
・ In flight (K-, N)
[ T. Kishimoto et al., Prog. Theor. Phys. 118 (2007), 181. ]
deep K-nucleus potential, ~ −200 MeV (analysis of missing mass spectra)
KEK, BNL
UK >> - 80 MeV( ΣKN ~ 150 MeV )
(4) Relation between kaon condensation in hadronic matter and that in quark matter
(c.f. phenomenological universal YNN, YYN, YYY repulsions [ S. Nishizaki, Y. Yamamotoand T. Takatsuka,
Prog. Theor.Phys. 108 (2002) 703. ] )
(2) Many-body forces
Stiffness of EOS at high density
(cf : RMF extended to BMM, MMM type diagrams) [K. Tsubakihara and A. Ohnishi, arXiv:1211.7208.]
Beyond mean-field approximation for baryon-baryon sector
(3) relativistic Hartree-Fock
Connection to quark matter
Introduction of tensor coupling of vector mesons
Cf. for hyperonic matter, [T. Miyatsu, T. Katayama, K. Saito, Phys. Lett.B709 242(2012).]
S-wave scalar int.S-wave vector int.
- Baryon interactions in K- field equation
repulsion for Σ- and Ξ- hyperons
Vector interaction between K- mesons and hyperons (Σ- and Ξ- ) works repulsively as far as > 0 , unfavorable for coexistence.
Chiral symmetry
K- field equation
The number density of K- mesons
< 0 for X0 << 0 .
The presence of K- condensates (θ) leads to a negative contribution to vector mean fields (ω0, R0 , φ0 ) . < 0
Vector mean fields
Scalar mean fields
Coulomb field
Equations of motion for meson fields
UK= − 180 MeV
Ground state
4-2. Density distributions (extremely attractive)
5-3. Comparison with kaon condensation in neutron stars
chemical equilibrium for weak processes
Chemical equilibrium for strong processes
Finite system formed in laboratory
ωK-
Finite effects of nuclei> μΛ ー μp
hard to satisfy
In neutron stars
K- chemical potential : = O(mπ) for high densities
ωK- =
dense infinite matter
Antikaons do not receive much attraction
Antikaons receive much attraction
Outlook
Many-body forces
Baryon-baryon sector
(cf : RMF extended to BMM, MMM type diagrams)
[K. Tsubakihara and A. Ohnishi, arXiv:1211.7208.]
Stiffness of EOS at high density
Searching for multi-strangeness nuclei in experiments
Search for fragments in Heavy-ion collisions
M(PSR J1614-2230) = 1.97 ± 0.04 M
3-4 Strangeness fraction
Kaonic nuclei
[A. Dote, H. Horiuchi et al., Phys. Lett. B 590 (2004) 51; Phys.Rev. C70 (2004) 044313. ]
kaonic nuclei by AMD
Highly dense and low temperature object
[ Y.Akaishi and T.Yamazaki, Phys.Rev. C65 (2002) 044005. ]Theoretical prediction based on deep K- potential
・ 4He (K- stopped, p), 4He (K- stopped, n)
・ In flight (K-,
N) ・ K- pp state
[A. Gal, R. S. Hayano (Eds.), Nucl. Phys. A804 (2008). ] For review articles,
[ T. Kishimoto et al., Prog. Theor. Phys. 118 (2007), 181. ]
KEK, J-PARC [ M. Iwasaki et al.T. Suzuki et al., Phys. Rev. C76, 068202(2007).]
deep K-nucleus potential, ~200 MeV (analysis of missing mass spectra)
[ M. Agnello et al., Phys. Rev. Lett. 94 (2005) 212303; Phys. Lett. B654(2007), 80. ]
Experimental searches
[E. Oset et al., arXiv: 0912.3145v1[nucl-th]. ]
Sharrow potential ~ 60 MeV in chiral unitary approach
FINUDA
[T. Yamazaki et al., arXiv: 1002.3526v1 [nucl-ex].]]DISTO Collaboration
KEK, BNL
[B. F. Gibson, K. Imai, T. Motoba, T. Nagae, A. Ohnishi (Eds.), proceedings of HYP-X, Nucl. Phys. A835 (2010). ]
interactions in matter Kaon condensation in neutron stars
kaonic nuclei search at J-PARC (K- pp, K-NNN, ・・・ )