Transcript Ξ核とΞN相互作用 - KEK理論センター・J

2015/8/4 JPARC
ΞN interaction and Ξhypernuclei
1. ESC08c model and Kiso event (long history)
2. Ξ- mixing in neutron star (extremely large hypernucleus)
Y. Yamamoto
湯川理論(1935)
坂田模型(1955) pnΛ
SU(3)対称性 IOO
八道説 バリオンオクテット
武谷核力論(1953)
OBEP
斥力芯
ハイパー核発見(1952)
BB相互作用模型
Nijmegen(from 197x)
ハイパー核とYN相互作用
観点(1990)
Baryon octet
Meson nonet
PS mesons
SU(3) invariant Yukawa interaction
independent constants
goct, gsin, α, (mixing angle θ)
以上は古い素粒子論の教科書に書いてある話
Parameter fitting for NN & YN scattering data
Nijmegen group from 1970’s
after that long long history to ESC08c
Parameters in ND/NF:
g8, g1, α, θ
4×4=16 parameters
for pseudo-scalar mesons
vector mesons (two terms)
scalar mesons
& hard-core radii
Continuous Studies by Nijmegen group since 1970’s
Parameter fitting with complementary use
of (rich) NN and (scarce) YN scattering data
Special modeling in ND
related to attractive ΞN interaction
not taken
Features of ND giving attractive UΞ
* special modeling for scalar mesons
* σ meson dominant attraction (universal in all channels)
* Wigner type (weak exchange interaction)
Hard Core modelは最初の一歩、核力屋の練習台
Soft Core model==> 模型の構築(ω, pomeron, QM, etc)
NDはHC故の現象論的性質（融通無碍） によって長々と生き延びた
もはや歴史博物館に収納
NDが長命になった理由の一つは引力的UΞの模型構築が
極めて困難であったことである
Long history to find mechanism of attractive UΞ in ESC modeli
quite difficult
Long history ～25 years !!!
Quark-core and UΣ / UΞ problem
UΣ
Experimentally repulsive
NSC89/97
attractive
ESC04a
strongly attractive
ESC04d
strongly attractive
ESC08a/b
ESC08c
UΞ
weakly attractive
strongly repulsive
weakly attractive
strongly attractive
strongly repulsive strongly attractive
moderately repulsive weakly attractive
Quark-core
effect
Ξ-hypernuclei and ΞN interaction in emulsion
no Ξ- can be seen
有史以前のデータ
Mondal, et al., Nuovo Cimento 54 (1979) 333
UWS=-24 MeV
（有史以前のパラダイム）
E176 events of twin Λ hypernuclei
Ξ-吸収によるダブルストレンジネス・
エマルジョン実験の問題点
Ξ-がどの軌道から吸収されたか分からない
一般的にイベントはユニークに同定できな
い
Λ- or ΛΛ-fragmentsは励起状態であり得る
複数のイベント・解釈から
consistent solution を見つ
ける
Twinの最初のドラフトのタイトルはΞハイパー核の生成
Atomic Ξ- cascadeでは1Sまで落ちない
2P
Coulomb
-bound
Coulomb
-assisted
E176 events
2P吸収でconsistent understanding, but
3D吸収の可能性は否定しきれない！
UWS ???
P.T.P. Suppl.117 (1994)
Y.Yamamoto, T.Motoba, T.Fukuda, M.Takahashi, K.Ikeda
UWS=-24, -16, -12, -8 MeV
D.J.Millener, C.B.Dover, A.Gal
neglect
UWS=-24 MeV
E885
T. Fukuda , et al., Phys. Rev. C58 (1998), 1306.
P.~Khaustov et al., Phys. Rev. C61 (2000), 054603
UWS=-14 MeV.
Twin E176
1993
Twin events を使った唯一の(?)理論の論文
Y-nucleus folding potential derived from YN G-matrix interaction G(r; kF)
G-matrix interactions
Averaged-kF Approximation
calculated
self-consistently
Mixed density
obtained from SkHF w.f.
横浜イベント
Recent : 0.82 +- 0.17 MeV
prediction
木曽イベント
!!!!!
WS pot (-18.3)
1S
8.00
2P
0.82
Ehime
5.10
0.82
1S
9.21
5.45
2P
1.61
1.17
E176
Kiso event
WS potential の予言性は低い
KISO event
木曽イベント
Some possibilities
Extended Soft-Core Model (ESC)
ΞNのみ調節する
パラメータはない
●Two-meson exchange processes are treated explicitly
● Meson-Baryon coupling constants are taken consistently
with Quark-Pair Creation model
repulsive cores
spin singlet
spin triplet
Why is UΞ so attractive ?
It’s due to tensor force
as well as NN and ΛN-ΣN
S12=0
.
T=0 3S1 : ΞN
T=1 3S1 : ΞN-ΛΣ-ΣΣ existence of S=-2 deuteron
UΛ (T=1/2 3S1) -21.2
+18.9 : ΛN-ΣN tensor
1.56 MeV
Origin of strong tensor force in ESC08c
π exchange (ΞN-ΞN)
K exchange (ΞN-ΛΣ)
Vector & Axial vector exchange
Meson-pair exchange
G-matrix folding model
model
ESC08c(ΞN)は適切な
引力を与える
EXP
(K-,K+) reactions
lead to neutron-rich
systems from
available targets
Various Ξ- nuclear bound states are produced by (K-,K+) rea
Cascade calculation  dominantly from 3d and 4f
a few % from 2p
by Koike & Akaishi
なぜ 2P Ξ- bound statesばかり見つかるのか？
Ξ-吸収によるダブルストレンジネス・エマルジョン実験
＊Ξ-がどの軌道から吸収されたか分からない
＊一般的にイベントはユニークに同定できない
＊Λ- or ΛΛ-fragmentsは励起状態であり得る
複数のイベント・解釈からconsistent solution を見つける
a consistent solution from some interpretations of events
2P-Ξ- absorption scenario
Deep hole state  cancelling of Δ
double-Λ sticking
2p-吸収によるdouble-Λ stickingの確率は3d-吸収の3倍
Double-Λ sticking from Ξ-absorption
through s-hole process
2pΞ  sΛpΛ  double-Λ sticking
3dΞ  pΛpΛ
pΛpΛ sticking state から double-Λ fragment や
twin Λ fragments への 崩壊確率は小さいであろう
Hyperon mixing in neutron-star matter
Ξ- mixing ?
Hyperon puzzle !
Massive (2M☉) neutron stars
2010 PSR J1614-2230 (1.97±0.04)M☉
?
2013 PSR J0348-0432 (2.01±0.04)M☉
Softening of EOS by hyperon mixing
Our conclusion :
The puzzle can be solved by
Universal Three-Baryon Repulsion
on the basis of terrestrial data
RMF
ours
Lagrangian in Baryon-Meson system
Bridge from “micro” to “macro”
RＭF
adjustable
parameters
interaction models
two + three-body
NN・YN scatteri
Many-body pheno
Earth-based experiments
no parameter as possible
Nuclear saturation properties
EOS in neutron-star matter
Based on BHF theory
Our story to neutron-star matter
starts from the BB interaction model
Nijmegen Extended Soft-Core Model (ESC)
SU3 invariant (NN and YN) interaction
repulsive cores
gP
2-body repulsion
Naturally
extended
g3P
SU3 scalar
universal repulsio
Pomeron is a model for multi-gluon exchange
A model of Universal Three-Baryon Repulsion
Multi-Pomeron Exchange Potential (MPP)
The same repulsions in all baryonic channels NNN, NNY
Effective two-body potential
from MPP (3- & 4-body
potentials)
Three-Nucleon attraction (TNA)
phenomenological
Both MPP and TNA are needed
to reproduce nuclear saturation property
but, essential is MPP for Nucleus-Nucleus
density-dependent two-body attraction
scattering data
Three parameter sets
4-body
How to determine coupling constants g3P and g4P ?
Nucleus-Nucleus scattering data
with G-matrix folding potential
Double Folding
U (R )   1 (r1 )  2 (r2 )vD (s;  , E )dr1dr2
 K s
  1 (r1 , r1  s)  2 (r2 , r2  s)vEX (s;  , E ) expi
dr1dr2

 M 
 VDFM (R )  iWDFM (R )
Frozen-Density Approximation ρ=ρ1+ρ2
Two Fermi-spheres separated in momentum space r
1
can overlap in coordinate space without
disturbance of Pauli principle
vNN(s)
r2
16O
+ 16O elastic scattering cross section at E/A = 70 MeV
10
real part
10
-2
d /d
-200
0
W (MeV)
0
-100
Ruth.
V (MeV)
0
ESC
Solid MPa
Dashed MPa+
Dotted MPb
-50
10
-100
0
-4
imaginary part
5
R (fm)
10
0
10
c.m.
20
(degree)
Planned experiments (Tanihata et al.) : 12C+12C@E/A=200, 300, 400 MeV
E/A curves
K value(MeV)
MPa+ 313
MPa 283
MPb 254
4-body
repulsion
MPa/MPa+ including 3- and 4-body MPP : MPb including 3-body MPP only
by solving TOV eq.
with n+p β-stable matter
4-body repulsion
K value(MeV)
MPa+ 313
MPa 283
MPb 254
No ad hoc parameter to adjust stiffness of EOS
Hyperon-Mixed Neutron-Star Matter
using YN & YY interaction model
ESC08c
MPP
TBA
consistent with almost all experimental data
of hypernuclei (S=-1,-2)
universal in all BB channels
given in S=0 channel  ? in S=-1,-2 channel
(ESC+MPP+TBA) model should be tested in hypernuclei
hyperonic sector
Choosing TBA=TNA
Experimental data of BΛ
reproduced
G-matrix folding model
no adjustable parameter
MPa is better
than ESC !!!
Existence of
three-body force effect
ESC
Reproducing all features in S=0,-1,-2 systems consistently
s.p. potentials for MPa
in neutron matter
MPP & TBA cancel with each o
around normal density region
features of ESC remain
Ξ- bound state
(Kiso event in emulsion)
28Si
(π-,K+) strength function
UΞ=1.5 MeVのG-matrix folding potentialが
UΞ=20-30 MeVのWoods-Saxon potentialと似た結果を与える
Hyperon-mixed Neutron-Star matter
with universal TBR (MPP)
EoS of n+p+Λ+Σ+e+μ system
ESC(YN) + MPP(YNN) +TBA(YNN)
Energy density
Hyperon-mixed neutron-star matter
Λ Σ-
Softening of EOS
by hyperon mixing
In spite of softening of EOS, 2Msolar is still obtained
PSR J1614-2230
Maximum mass for MPb (no 4-body repulsion) is less than 2Msolar
Ξ- mixing
Maximum mass is not changed by Ξ- mixing
Conclusion
ESC+MPP+TBA model
* MPP strength determined by analysis for 16O+16O scattering
* TNA adjusted phenomenologically to reproduce
saturation properties
* Consistent with hypernuclear data
* No ad hoc parameter to stiffen EOS
MPa/MPa+ set including 3- and 4-body repulsions
leads to massive neutron stars with 2M☉ in spite
of significant softening of EOS by hyperon mixing
MPb including 3-body repulsion leads to slightly smaller
value than 2M☉ quantitatively
Ξ- mixing does not change the maximum mass
when (MPP+TBA) is added to ΞN interaction