yn/yy 相互作用とハイパー核 Ξn interaction をめぐって
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YN/YY 相互作用とハイパー核 ΞN interaction をめぐって. 2007/3/2 伊勢志摩. Y. Yamamoto Tsuru University. 核力から核構造・反応へ. 核物理の原点 ・ Shell model の成立 ・ BBG theory. G-matrix. lowest order. G-matrix theory は核物理における確立した基礎理論 有用なツール. Nuclear Saturation Problem は基本的には解決済み. Nuclear saturation curve for ESC04. 中性子星. - PowerPoint PPT PresentationTRANSCRIPT
YN/YY 相互作用とハイパー核ΞN interaction をめぐって
Y. YamamotoTsuru University
2007/3/2 伊勢志摩
核力から核構造・反応へ
核物理の原点・ Shell model の成立・ BBG theory G-matrix
lowest order
G-matrix theory は核物理における確立した基礎理論 有用なツール
Nuclear Saturation Problem は基本的には解決済み
Nuclear saturation curve for ESC04
Fujita-Miyazawa
including MIR
MIR is quite similar to Illinois-TBR
中性子星
Nucleon optical potential
Hyperon-nucleus potential
derived in the same frameworkfrom underlying BB interactions
背景に同じ物理がある
核力 G-matrix interaction folding
核力から核構造YN/YY hypernuclei
本当の意味は?
bare interaction を使って計算すれば良いということではない!
π
玉垣さんのテキストより
π
核力の特性とメソンの役割
● OPEP tail π● 領域Ⅱの強い引力 “ σ”● テンソル力 π-ρ● LS 力 “ σ”+ω+ρ ● repulsive core
原子核の性質領域Ⅲの性質は顕著には現れない(ひっそりと支える)テンソル力は2次項が支配的役割
QM core ?
原子核における π もしくはテンソル力
dominant rolesdominant roles “σ” の実体、3体力 saturation のコントロール
minor rolesminor roles OPEP tail effective tensor による weak mixing
by 玉垣さん2000/7Before NAGARA
σ-meson の実体
Fujita-Miyazawa TBF
核力における引力の主要項
2π-exchange via Δ-excitation
ΛΛΛΛ 引力は弱い引力は弱い
ESC では pair terms
PS, S, V, AV nonets
PS-PS exchange
(ππ),(πρ),(πω),(πη),(σσ)
not taken
ESC modeling
Repulsive core の成因
ESC ポメロン +ω チャネル・状態依存性はあまりない
FSS/fss2 QM に特有のチャネル依存性がある
ハイパー核で領域Ⅲを見れるか?
領域Ⅲ
実は ESC04 の顕著な特質は r<1 fm に依拠しているheavy mesons
Region Ⅲ = repulsive core ではない !? 豊かな物理 ?
ハイパー核物理の目標Λ 核の諸特性、 Σ 核、 ΛΛ 核、 Ξ 核 ・・・多様な存在形態を相互作用の特質(mesons & core) と関連付けて統一的に理解すること
S=0 系には登場しない多彩なメソンの役割は?領域Ⅲの特質はいかに発現するか?
YN/YY 相互作用の研究はストレンジネス多体系の新たな質の発見と連動する現在進行形である
ESC-modeling における新たな実体(多様な pair terms 、 AV mesons)の導入は、その方向に沿った試みである
attractive UΞ 、 repulsive UΣ 、 small s.o. splitting
BNL-E885
U0 ~ -14 MeV
Motoba’s calculation
P-state nuclearbound state
UΞ ~ -16 MeV
KEK-E176
Our methodology
① Study of Ξ hypernuclei/ΞN interaction is in a phenomenological stage ( 現象論的段階)
② Our starting point is to consider the experimental suggestions of attractive UΞ( ~ -14MeV) as a working assumption ( 作業仮説)
③ ΞN interaction models giving rise to attractive UΞ
are investigated through structure calculations for Ξ hypernuclei
Special modeling in NDrelated to attractive ΞN interaction
not taken
まずは古い話から・・・
ΞΞNN NNNN
No space-exchange component in VΞN(OBE)because S=-2 cannot be carried by a boson
Another possibility ESC04dESC04d
A longstanding model giving attractive UΞ
NHC-DNHC-D
Special modeling to include only singlet scalar meson (σ)
NHC-FNSC89NSC97
repulsive!
What difference from NHC-D ?
Extended Soft-Core Model ESC0 4
●Two-meson exchange processes are treated explicitly no effective bosons are used
●PS, S, V, AV meson-nonets are taken into account
● Meson-Baryon coupling constants are consistent with Quark-model predictions
Parameter fitting G-matrix Hypernuclear data
not only YN scattering data
Phys. Rev. C73, 044008 (2006)
Different predictions for Ξ hypernuclear states
most interesting for Ξstates
From the particle-physics point of viewFrom the particle-physics point of viewESC04d is favoredESC04d is favored 1. pv-coupling for the pseudo-scalar mesons1. pv-coupling for the pseudo-scalar mesons 2. SU3-symmetry for the couplings2. SU3-symmetry for the couplings
ESC06
ESC04
Too complicated ???
ΛΛ phase shifts
Old data
NagaraPair
Pair
Strong ΛΛ-ΞN coupling from Pair terms
Total
Total ( repulsion )
OBE
diagonal coupling
Pair
Exp ~ 1.0
ESC04 models are consistent with NAGARA data
Strong Ξ N -ΛΛ coupling
strong P-state attractionStrong 13S1 attraction !
Adjustable parts: ESC04 Medium-induced repulsion NHC-D Hard-core radius
Specific bound states in 2-,3-,4-body systems
OBE
Pair
Total
ΛN: Pair attractive OBE repulsive
On the other hand
Λ N caseCanceling of Scalar and VectorCanceling of Scalar and Vector
S
V
S
V
OBEOBErepulsiverepulsive
PairPairattractiveattractive
PS V
S AV
OBE attraction in Ξ N 13S1 state
Canceling ofV and AV
Attraction of S appears
cancel
attractive
ω
a1
ε
A folding model for Ξ-hypernuclei
Density-dependent G-matrix interaction
Lane term
includingimaginarypart
(standard in derivations of optical potential)
Ξ-+closed-core systems
Mass-dependenceConversion widthNote!Note!
adjusted
Ξ hypernuclei produced by (K-,K+) reactions on available targets
Lane term ~ (N-Z+1)/4
(K-,K0)
N=Zcores
N>Zcores
available
with ESC04d
(K-,K+)
Features of ESC04d and NHC-D
ESC04d NHC-D
Mass-dep of BΞ weak strong
Lane term strong weak
light Ξ-states ○ ×
Conversion width large small
In the case of FSS/fss2
Conclusion ( ESC04 and Ξhypernuclei )
A ”solution” of ESC04 modeling leads to attractive UΞ
U0≒-14 MeV(if true) is realized by strong strong 1313SS11 attraction attraction in ESC04 model
There exist some s-shell some s-shell ΞΞ-bound states-bound statesdominated by 13S1 components
Conversion width ΓΞ is large due to strong ΞN-ΛΛ coupling in 11S0 state
These features are completely different from FSS/fss2 models!!!