Hypernuclear structure and the photoproduction

T. Motoba (Osaka E-C)

HaPhys Workshop 2014

Soongsil University, Seoul March 3 - 4, 2014

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Recollecting: APCTP Workshop on Strangeness Nuclear Physics (1999) Seoul Nat. Univ., ｓｕｃｃｅｓｓｆｕｌｌｙ organized by Il-T. Cheon (Yonsei), S.-W.Hong (Sunkyunkan) and T.Motoba (Osaka E-C.)

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CONTENTS 1．Introduction

2. How to produce hypernuclei: Elementary processes

3. Reaction Theories for hypernuclear production

4. Extended structure calculations for hypernuclear

spectroscopy

4-1. Light hypernucleus with microscopic

cluster model (9LBe)

4-2. Shrinkage effect by L addition (7LLi)

4-3. Heavy hypernucleus vs. (p+,K+) reaction

4-4. (g,K+) reaction to produce sd-shell and

heavier systems 5. Concluding remarks 3

1. Introduction

4 (From H. Tamura)

5

More bound states: Hypernuclei provide us with new opportunities to study V(Y-N) and dynamics of new baryon many-body systems.

6 Taken from N. Nakamura, based on O. Hashimoto and H. Tamura

Progress in disclosing L

9Be level structure

high precision

g-rays (Tamura e tal)

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Microscopic Cluster model, Motoba, Bando, Ikeda, PTP79, 189 (1983)

2. Elementray hyperon production processes and the characteristics

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Three factors: 1. Hyperon recoil momentum 2. Selectivity due to process 3. Cross section

(1) Hyperon recoil momentum qY as a function of projectile momentum

(2) Selectivity of hypernuclear production

(K-,π-) at p=0.8 GeV/c: > Recoilless production of Λ > substitutional states with

ΔL=0,1

(π+,K+) at p=1.05 GeV/c: > Natural parity high-spin

stretched states (g,K+) at p=1.3 GeV/c: > Unnatural parity high-

spin states

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qL=350-420 MeV/c at Eg=1.3 GeV

(3) Cross section and polarization

11 Cf. K- beam at J-PARC

3. Production of Hypernuclei: Reactions on the nuclear target

Four factors: 1. PW vs. DW (Meson DW effects) 2. Microscopic treatment with elem. amplitudes, 3. Nuclear target has its own structure 4. Nuclear core excitation effects on hypernuclear production rates

(p+,K+)

(g, K+)

(K-,K+)

外側の軌道

19F(g ,K+) D19O 16O

閉殻

陽子の軌道中性子の軌道

0d3/2 1s1/2 0d5/2 0p1/2 0p3/2 0s1/2

0d3/2 1s1/2 0d5/2 0p1/2 0p3/2 0s1/2

0d3/2 1s1/2 0d5/2 0p1/2 0p3/2 0s1/2

0d3/2 1s1/2 0d5/2 0p1/2 0p3/2 0s1/2

0d3/2 1s1/2 0d5/2 0p1/2 0p3/2 0s1/2

0d3/2 1s1/2 0d5/2 0p1/2 0p3/2 0s1/2

Λ 粒子の生成軌道

8MeV

-2.5MeV

-13MeV

E

0d3/2 1s1/2 0d5/2 0p1/2 0p3/2 0s1/2

0d3/2 1s1/2 0d5/2 0p1/2 0p3/2 0s1/2

0d3/2 1s1/2 0d5/2 0p1/2 0p3/2 0s1/2

0d3/2 1s1/2 0d5/2 0p1/2 0p3/2 0s1/2

0d3/2 1s1/2 0d5/2 0p1/2 0p3/2 0s1/2

0d3/2 1s1/2 0d5/2 0p1/2 0p3/2 0s1/2

Choose 19F(1/2+) target for demonstration

neutron proton

L (DDHF) Shell-model configuration

1s1/2

γ 線によるハイパー核Λ 19Oの生成断面積

0

10

20

30

40

50

60

-20 -15 -10 -5 0 5 10 15 20

ハイパー核励起エネルギー〔ＭｅＶ〕

生成

断面

積〔

μb/sr〕

合計

1s1/2

0p1/2

0p3/2

19F(g,K+) L19O

SUM of the partial contributions

As a “closed core (18O)”+ L , cf. SO-splitting(0p)=152+/-54 keV(C13)

A BRIEF LOOK INTO REACTION THEORIES (A) FACTORIZED VS. (B) MICROSCOPIC

(A) Factorized DWIA treatment by Huefner-Lee-Weidenmueller, NPA234, 429 (1974)

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a = kinematical factor for A-body to 2-body transformation,

Neff= Effective neutron number :

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(A-1) Meson waves by the Eikonal approximation

(A-2) Meson DW with the Klein-Gordon solutions (Ours)

Applicable to forward scattering, 10-20% error of K-G DW ( Auerbach et al (1983).

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PW vs. DW

(1)

In a typical (π+,K+):

Neff = 0.184 (PW)

0.030 (DW)

(2)

XS to low-J states

are much more

reduced, resulting in

the sharper peaks

(3) Interesting DW

effect (mechanism）

Low-L partial waves are more reduced by absorption effect, leading to well-separated high-L series of peaks

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(B) Microscopic treatment based on the

elementary transition amplitudes

Elementary amplitude N Y

f = spin-nonflip, g= spin-flip , σ= baryon spin

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R(i,f ;M) is expressed with three kinds of

the reduced effective numbers

Magnetic subspace population P(i,f : M) is

defined by

Polarization of Hypernuclear state | Jf > is

calculated by

Most sophisticated treatment

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4. Detailed hypernuclear structure Calculations vs. Reaction spectroscopy

Extend the calculation framework to predict/explain experimental strength functions: (four examples selected)

4.1 Microscopic cluster model applied to L9Be

4.2 Microscopic cluster model applied to L7Li

4.3 Shell-model analyses of 89Y(p+,K+) L89Y

4.4 Shell-model prediction for 28Si(g,K+) L28Al

4.1 Microscopic cluster model applied to L

9Be

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All the existing exp.data can be explained.

4.2 Shrinkage effect due to the L participation to the nucleus

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Shrinkage due to Λ participation ( “glue-like role” of Λ )

T. Motoba, H. Bando and K. Ikeda, Prog. Theor.Phys.70 (1983) predicted by Microscopic α＋ｄ＋Λ model

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Renewed Calculation by E. Hiyama, M. Kamimura,

K. Miyazaki, and T. Motoba, Phys. Rev. C59, 2351 (1999),

Microscopic Λ5He＋p＋n model to see free p and n dynamics.

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Contraction of Rcore-(pn) without changing p-n

distribution (Hiyama et al, 1998)

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B(6Li,E2:3+1+) vs. B(Λ7Li,E2;5/2+1/2+)

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Shrinkage: glue-like role of Λ confirmed

B(E2) in e2fm4

Dalitz

-Gal

Shell M.

(1978)

Motoba

et al.

3-Cluster

(1983)

Hiyama

et al.

3-Cluster

(1998)

EXP.

Tamura

et al (1998,

2000,2001)

B(M1:3/2+1/2+) 0.364 0.352 0.322 -

B(E2:5/2+ 1/2+)

*eff.chrg: δe=0.15e

8.6 2.46

( 4.16*)

2.42

( 4.09*)

4.1+-1.1

B(E2:5/2+ 3/2+) 3.1 0.40 0.74

B(E2:5/2+all)/B(E2)c 1.0

assumed

0.44 0.33

ΓB 0.49 0.32

Rcd(7Li)/Rαd(6Li) 0.83 0.75 0.87

Lifetime(5/2+) ps 6.56 6.67 5.2+-1.4 33

4.3 Shell-model analyses of 89Y(p+,K+) L

89Y

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Probe deep-lying Λ single-particle states

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For [(0lnjn)-1(0lLjL)]J

F.F becomes maximum at J=(bq)2/2

How to understand L89Y data (Hotchi et al, PRC64

(2001) in view of CAL(Motoba et al, 1988)

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40 40

3L and 3R peaks as a function of d

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Spin-spin and spin-orbit splitting

at A=90

Nijmegen B-B interaction model improved by taking account of hypernuclear data

4.4 Theoretical prediction vs. Jlab experiment

28Si(g,K+) L28Al

and other predictions

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Cf. energy resolution

(K-,p-) G = 3-4 MeV

(p＋,K+) played a great role of

exciting high-spin series G = 1.5 MeV (best)

(e,e’K+), (g, K+)

Motoba. Sotona, Itonaga, Prog.Theor.Phys.S.117(1994)

T.M. Mesons & Light Nuclei (2000) updated w/NSC97f.

------------------------------- JLab Exp’t : G = 0.5 MeV

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Lab ds/dW for photoproduction (2Lab)

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Spin-flip interaction are dominant

A typical example of medium-heavy

target :28Si: (d5/2)6

to show characteristics of the (g,K+) reaction with DDHF w.f.

( Spin-orbit splitting:

consistent with L7Li, 9Be,13C, 89Y )

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4.4a Single-j model for

the 28Si target

)

Theor. x-section for (d5/2)6 (g,K+) [ ｊh-ｊL]J

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4-4b. Realistic prediction for 28Si (g,K+)

L28Al

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By fully taking account of -- full p(sd)6.n(sd)6 configurations, -- fragmentations when a proton is converted, -- 27Al core nuclear excitation -- K+ wave distortion effects Comparison with the 28Si (e,e’K+) exp.

proton-state fragmentations should be taken into account to be realistic

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Proton pickup from 28Si(0+):(sd)6 =(d5/2)4.1(1s1/2)

0.9(d3/2)1.0

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Peaks can be classified by the characters

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Exp. data: Fujii et al, Proc. SNP12 workshop (2012) Great progress when compared with

cf. 28Si(pi+,K+)

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Exp. data: Fujii et al, Proc. SNP12 workshop (2012) Theory: P. Bydzovsky, T. Motoba, …. , Nucl. Phys.A881(2012) Seems promising, (waiting for the finalization of exp. analysis)

40Ca ( LS-closed shell case): high-spin states with natural-parity (2+,3-,4+)

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Elem. ampl. Theor. prediction vs. (e,e’K+) exp.

Theory

Motoba. Sotona, Itonaga,

Prog.Theor.Phys.Sup.117 (1994)

T.M. Mesons & Light Nuclei (2000)

updated w/NSC97f. -------------------- Sotona’s Calc.----

Hall C (up) T. Miyoshi et al. P.R.L.90 (2003) 232502. G=0.75 MeV

Hall A (bottom), J.J. LeRose et al. N.P. A804 (2008) 116. G=0.67 MeV

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Theor. vs. Exp. Test of elem. Ampli.

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Possible test of gp->LK ampl.

59 (From P. Bydzovsky )

6. Concluding remarks

1) discussed interesting topics selected in hypernuclear spectroscopy , by focusing the relation with production processes.

2) emphasized novel aspects of many-baryon systems with hyperon(s).

3) emphasized importance of producing medium and heavy hypernuclei with good energy esolution.

4) skipped the details of YN interactions, those experiments will provide with interesting dynamical structures together with YN interaction properties.

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Life of strange many-body systems

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Thank you for your attention.

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