1.Introduction 2.Exotic properties of K nuclei 3.Recent experimental results Strange tribaryons by KEK experiment ppK - by FINUDA ppnK - by FOPI 4.Future

1. Introduction

2. Exotic properties of K nuclei

3. Recent experimental results• Strange tribaryons by KEK experiment• ppK- by FINUDA• ppnK- by FOPI

4. Future developments

5. Summary and future plans

Exotic system: Kaonic nuclei the present status and the future development

Exotic system: Kaonic nuclei the present status and the future development

QCD とハドロン物理の新展開 @ KEK, ’06.Mar.1

A. Dote （ KEK ） Y. Akaishi (Nihon univ.) T. Yamazaki (RIKEN)

´

Introduction

What are kaonic nuclei (K nuclei)?

K- meson is bound in a nucleus by strong interaction.

cf) Kaonic atom K- meson is around a nucleus, bound by Coulomb interaction.

K nuclei can exist as discrete states, since K- meson is deeply bound below Σπ threshold.

KNNN…

ΣπNN…

K nuclear state

K nuclear state

Deeply bound; Binding energy of K- > 100 MeVDiscrete state; Below Σπ threshold

Very attractive I=0 KN interaction makes …

... Deeply bound kaonic nuclei

1. free KN scattering data2. 1s level shift of kaonic hydrogen atom3. binding energy and width of Λ(1405)

Phenomenological KN potential (AY KN potential)

Strongly attractive.

0KN

IV 0KN

IV

Y. Akaishi and T. Yamazaki, PRC 52 (2002) 044005

= K- + proton

0 11 34

4 4I Ig g

0 1

2

13

2

1 I Ig g

0 1

2

13

2

1 I Ig g

My motivation

Only one K- meson can drastically change the nuclear structure?

Only one K- meson can drastically change the nuclear structure?

Y. Akaishi and T. Yamazaki, PRC 52 (2002) 044005

8Be + K-

… Akaishi’s special lecture held in Kyoto university in ’00.

Exotic features of K nuclei

Fully microscopic treatment

No assumption on nuclear structure; cluster, deformation …

System self-organizes only following energy variation.

p

n

Normal nucleus

p

n

normal nucleus

? ?? ?? ?? ?

Kaonic nucleus

What kind of structure does A+1 system favor?

Anti-symmetrized Molecular DynamicsAnti-symmetrized Molecular Dynamics

Essence of AMD

det

det

det

Cooling

det

0s

0p

Shell

det

Cluster

Gaussian wave packet

AMD wave function can describe not only shell-model-like structure but also cluster-like one.

The structure is determined by only the energy-variation.

The structure is determined by only the energy-variation.

☆ Improve AMD for K nuclei

mixing- 0K p-K n

-K p 0K n

0KN

IV 0KN

IV

0

proton neutronN a b

K x K y K

+ Charge projection of total wave function

Single nucleon/kaon wave function

Hamiltonian in AMD calculation

CMNN KN CoulombH T V V V T

: effective NN int. 　　　　　　　　 Tamagaki potential (OPEG)

: effective KN int. 　　　　　　　　 AY KN potential

NNV

KNV

G-matrix methodY. Akaishi and T. Yamazaki,

PRC 52 (2002) 044005

We used only central potential as VNN

before the discovery of strange tribaryons.

A. D., H. Horiuchi, Y. Akaishi and T. Yamazaki, PLB 590 (2004) 51; PRC 70 (2004) 044313.

AMD studies revealed …

1. E(K) > 100 MeV for various light nuclei

2. Drastic change of the structure of 8Be, isovector deformation in 8BeK-

3. Highly dense state is formed in K nuclei. maximum density > 4ρ0

averaged density 2 ～ 4ρ0

4. Proton satellite in pppK-

Rrms = 2.46 fmβ = 0.63

Central density = 0.10 /fm^3

8Be

Density (/fm^3) 0.0 0.10 0.20

-160.0

-140.0

-120.0

-100.0

-80.0

-60.0

-40.0

-20.0

0.0ppnK pppK pppnK 6BeK 8BeK 9BK

E(K)

[M

eV]

Nucleus-K- 　 threshold

Σπ threshold

(simple AMD)

Width (Σπ, Λπ)

Rrms = 1.42 fmβ = 0.55

Central density = 0.76 /fm^3

8BeK-

Density (/fm^3) 0.0 0.41 0.83

4.5 normal density

Binding energy of K- = 104 MeV

Isovector deformation

0 1KN

IIKNVV

K p K nV V

pppK-

Proton satellite

Various shapes of K nuclei

ppnK- pppK- pppnK-

6BeK-

3 fm

9BK-

4 fm

8.8ρ0 9.2ρ0 7.6ρ0

5.4ρ0 4.1ρ0

1.141.67 1.78

2.55 2.53

1( )

5 MAX K

4 fm

4.1ρ0

Single K- meson can interact with limited numbers of nucleons?

Saturation of E(K)

Recent experimental results

T. Suzuki, M.Iwasaki et al; 4He(stopped K-, n or p) @ KEK

H. Fujioka, T. Nagae et al; ppK- @ DAΦNE

Kishimoto et al; 16O(inflight K-, n) 15OK- @ BNL

• N.Herrmann et al; Invariant-mass method (heavy-ion collision) @ GSI

• K. Suzuki et al; proton induced reaction @ GSI

• J-PARC

Various groups are trying to search for deeply bound kaonic nuclei in various way.

KEK group

ppnK-

(T=0)

ppnK-

(T=0)

4He (stopped K-, n) ppnK- 4He (stopped K-, p) pnnK-

pnnK-

(T=1)

pnnK-

(T=1)

T. Suzuki, M. Iwasaki et al

• KEK• Stopped K- reaction on 4He target• Missing-mass method (Detecting p or n)

ppnK- :Strange tribaryon S+(3140)

arXiv: nucl-ex/0310018

Total binding energy = 169 MeVDecay width < 25 MeV

pnnK- :Strange tribaryon S0(3115)

PLB 597, 263 (2004)

Total binding energy = 194 MeVDecay width < 21 MeV

FINUDA group H. Fujioka, T. Nagae et al

• e+e- collider DAΦNE, FINUDA spectrometer• K- absorbtion at rest on various nuclei• Invariant-mass method

Strong correlation between emitted p and Λ(back-to-back) Invariant mass of p and Λ

ppK-

Total binding energy = 115 MeVDecay width = 67 MeV

PRL 94, 212303 (2005)

6 35 4

14 211 3

FOPI group

• GSI• Heavy-ion collision Ni+Ni @ 1.93 A GeV• Invariant-mass method

Invariant mass of d and Λ

N. Herrmann et al

ppnK-

Total binding energy = ～ 150 MeVDecay width = 100 MeV ?

Preliminary !

Preliminary !

Summary of present status

Our predictions

B.E. = 48 MeVΓ = 61 MeV

B.E. = 118 MeVΓ = 21 MeV

B.E. = 87 MeVΓ = 133 MeV

KEK B.E. = 169 MeVΓ < 25 MeV

B.E. = 194 MeVΓ < 21 MeV

FINUDA B.E. =115 MeVΓ = 67 MeV

FOPI B.E. ～ 150 MeVΓ ～ 100 MeV

ppK- ppnK- pnnK-


Our predictions

B.E. = 48 MeVΓ = 61 MeV

B.E. = 118 MeVΓ = 21 MeV

B.E. = 87 MeVΓ = 133 MeV


B.E. = 194 MeVΓ < 21 MeV



ppK- ppnK- pnnK-

Experimental results are more deeply bound than ours.



Our predictions

B.E. = 48 MeVΓ = 61 MeV

B.E. = 118 MeVΓ = 21 MeV

B.E. = 87 MeVΓ = 133 MeV


B.E. = 194 MeVΓ < 21 MeV



ppK- ppnK- pnnK-


Experimental results are more deeply bound than ours.•14% enhanced KN interaction•NN-LS interaction is important in pnnK-.

•14% enhanced KN interaction•NN-LS interaction is important in pnnK-.

B.E. = 177 MeV

B.E. = 177 MeV

B.E. = 187 MeV

B.E. = 187 MeV

Jπ=1/2-, T=0

(0s)3

Jπ=3/2+, T=1

(0s)2(0p)

• Isobaric analog state of pppK-

• Large energy gain by KN interaction

• Additional energy gain by NN-LS interaction

Nucleon configuration of pnnK-

I=0 KN

I=1 KN

1 / 6

5 / 6

2 / 3

1 / 3

1 / 2

1 / 2

ppnK- pnnK-

(0s)3 (0s)3 (0s)2(0p)

T=0 T=1

P nK-

p n

K- K0


Our predictions

B.E. = 48 MeVΓ = 61 MeV

B.E. = 118 MeVΓ = 21 MeV

B.E. = 87 MeVΓ = 133 MeV


B.E. = 194 MeVΓ < 21 MeV



ppK- ppnK- pnnK-

Decay width is consistent?Decay width is consistent?


Our predictions

B.E. = 48 MeVΓ = 61 MeV

B.E. = 118 MeVΓ = 21 MeV

B.E. = 87 MeVΓ = 133 MeV


B.E. = 194 MeVΓ < 21 MeV



ppK- ppnK- pnnK-

Consistent?Especially, decay width.

Consistent?Especially, decay width.


Our predictions

B.E. = 48 MeVΓ = 61 MeV

B.E. = 118 MeVΓ = 21 MeV

B.E. = 87 MeVΓ = 133 MeV


B.E. = 194 MeVΓ < 21 MeV



ppK- ppnK- pnnK-

??? ???

??? ???

???

Unobserved states can be found by each other experiment?

Unobserved states can be found by each other experiment?

Future developmentsTheory

1, Short-range repulsive core part of NN interaction The repulsive core part of the effective NN potential derived by G-matrix method is too much smoothed out for the study of kaonic nuclei?

“Beyond the conventional nuclear physics”

3, Mystery of two-body absorption (KNN --> YN) … large decay width at high density K nuclei can survive?

2

4, The study from the view point of quarks; Quark matter or not?

2, Using more theoretical KN interaction• Energy- and density-dependence• I=1 P-wave interaction … Attractive below Σ(1385). … Large contribution at high density?

,KN P waveV C r

EEEEEEEEEEEEEEEEEEEEEEEEEEEE

Additional attraction to

deeply bound kaonic nuclei

Future developmentsExperiment

1, More experiments to confirm the existence of kaonic nuclei

2, Determine Jπ of , especially, strange tribaryons

3, Dense or not?

　　 Possible by measuring the momentum correlation of three particles emitted in the decay NNNK → N+N+Λ P. Kienle, Y. Akaishi and T. Yamazaki, Phys.Lett.B632, 187 (2006)

Summary Kaonic nuclei have interesting properties! The AMD study with AY KN interaction showed …

• K- is deeply bound by ～ 100 MeV and forms highly dense state.

• Strange structures appear in K nuclei. Drastic change of 8Be structure, Isovector deformation in 8BeK-, Proton satellite in pppK-.

Observed strange tribaryons, ppnK- and pnnK-, can be understood …

• 14% enhanced KN interaction and NN-LS force• pnnK- : (0s)2(0p) configuration Jπ=3/2+, T=1• ppnK- : (0s)3 configuration Jπ=1/2-, T=0

Summary

Various experimental results are now reported. They indicate the evidence of deeply bound kaonic nuclei.

But comparing with each other, there seems to be some inconsistency between them.

In particular in decay width.

KEK; narrow FINUDA and FOPI; broad

Need more experiments!

Study more various K nuclei

Double K nuclei?

Other type of KN interaction?

Many experiments will start, or started.

T. Suzuki, Iwasaki et al; 4He(stopped K-, n or p) @ KEK Fujioka, Nagae et al; ppK- @ DAΦNE Kishimoto et al; 16O(inflight K-, n) 15OK- @BNL• Herrmann et al; Invariant-mass method (heavy-ion collision) @ GSI• K. Suzuki et al; proton induced reaction @ GSI• J-PARC

I=1 p-wave KN interaction … suggested by S. Wycech et al. 　 nucl-th/0501019Collaborate with W. Weise

Study K nuclei from the viewpoint of quarksCollaborate with Y. Kanada-En’yo and O. Morimatsu

Λ(1405) = qqq-qq, ppK- = 7qq, ppnK- = 10qq (undeca-quarks state)- - -

Apply our wave function to the study of reaction

Dense or not? (S. Hirenzaki and J. Yamagata)

Future plans

Kaonic nucleus

K nuclei… 　 Exotic system !

… related to various fields!!

KN interaction

Cold and Dense

Kaonic atom

Λ （１４０５）

Interesting structure… Nuclear structure

Kaon condensation

(Strange) Quark matter

Chiral symmetry restoration

Documents

1.Introduction 2.Exotic properties of K nuclei 3.Recent experimental results Strange tribaryons by KEK experiment ppK - by FINUDA ppnK - by FOPI 4.Future