Hypernuclear structure and the photoproduction

Transcription

1 Hypernuclear structure and the photoproduction T. Motoba (Osaka E-C) HaPhys Workshop 2014 Soongsil University, Seoul March 3-4,

2 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.) 2

3 1.Introduction CONTENTS 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 ( 9 LBe) 4-2. Shrinkage effect by L addition ( 7 LLi) 4-3. Heavy hypernucleus vs. (p+,k+) reaction 4-4. (g,k+) reaction to produce sd-shell and heavier systems 5. Concluding remarks 3

4 1. Introduction (From H. Tamura) 4

5 More bound states: Hypernuclei provide us with new opportunities to study V(Y-N) and dynamics of new baryon many-body systems. 5

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

7 Progress in disclosing L9 Be level structure high precision g-rays (Tamura e tal) Microscopic Cluster model, Motoba, Bando, Ikeda, PTP79, 189 (1983) 7

8 2. Elementray hyperon production processes and the characteristics Three factors: 1. Hyperon recoil momentum 2. Selectivity due to process 3. Cross section 8

9 (1) Hyperon recoil momentum qy as a function of projectile momentum

10 (2) Selectivity of hypernuclear production q L = MeV/c at Eg=1.3 GeV (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 highspin states 10

11 (3) Cross section and polarization Cf. K- beam at J-PARC 11

12 3. Production of Hypernuclei: Reactions on the nuclear target (p+,k+) (g, K+) (K-,K+) 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

13 Choose 19 F(1/2 + ) target for demonstration 0d 3/2 1s 1/2 0d 5/2 0p 1/2 0p 3/2 0s 1/2 外側の軌道 0d 3/2 1s 1/2 0d 5/2 0p 1/2 0p 1s 1/2 3/2 0s 0d 1/2 3/2 1s 1/2 0d 0d 1s 1/2 0d 5/2 0p 1/2 0p 3/2 0s 3/2 1s 1/2 0d 1/2 8MeV 5/2 0p 0d 3/2 1s 1/2 0d 5/2 0p 1/2 0p 3 E 0d 5/2 0p 1/2 0p 3/2 0s 1/2 16 0pO 1/2 0p 3/2 0s 1/2 閉殻 0p 3/2 0s 1/2 Shell-model 中性子の軌道 configuration 陽子の軌道 0d 3/2 1s 1/2 0d 5/2 0p 1/2 0p 3/2 0s 0d 3/2 1s 1/2 0d 5/2 0p 1/2 0p 3/2 0s -2.5MeV 1/2 0d 3/2 1s 1/2 0d 5/2 0p 1/2 0p 3/2 0s 1/2 neutron proton Λ 粒子の生成軌道 L (DDHF) -13MeV

14 合計 1s1/2 0p1/2 0p3/2 19 F(g,K + ) L 19 O SUM γ of 線によるハイパー核 the partial Λ 19Oの生成断面積 contributions 生成断面積 μ b/sr ハイパー核励起エネルギー MeV 0 As a closed core ( 18 O) + L, cf. SO-splitting(0p)=152+/-54 kev(c13)

15 A BRIEF LOOK INTO REACTION THEORIES (A) FACTORIZED VS. (B) MICROSCOPIC (A) Factorized DWIA treatment by Huefner-Lee-Weidenmueller, NPA234, 429 (1974) a = kinematical factor for A-body to 2-body transformation, Neff= Effective neutron number : 15

16 (A-1) Meson waves by the Eikonal approximation Applicable to forward scattering, 10-20% error of K-G DW ( Auerbach et al (1983). (A-2) Meson DW with the Klein-Gordon solutions (Ours) 16

17 PW vs. DW (1) In a typical (π+,k+): Neff = (PW) (DW) (2) XS to low-j states are much more reduced, resulting in the sharper peaks (3) Interesting DW effect (mechanism) 17

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

19 (B) Microscopic treatment based on the elementary transition amplitudes Elementary amplitude N Y f = spin-nonflip, g= spin-flip, σ= baryon spin 19

20 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 20

21 21

22 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 L9 Be 4.2 Microscopic cluster model applied to L7 Li 4.3 Shell-model analyses of 89 Y(p+,K+) L 89 Y 4.4 Shell-model prediction for 28 Si(g,K+) L 28 Al

23 4.1 Microscopic cluster model applied to L9 Be 23

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27 All the existing exp.data can be explained.

28 4.2 Shrinkage effect due to the L participation to the nucleus 28

29 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 29

30 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. 30

31 Contraction of Rcore-(pn) without changing p-n distribution (Hiyama et al, 1998) 31

32 B(6Li,E2:3+ 1+) vs. B(Λ7Li,E2;5/2+ 1/2+) 32

33 Shrinkage: glue-like role of Λ confirmed Dalitz Motoba Hiyama EXP. B(E2) in e 2 fm 4 -Gal Shell M. (1978) et al. 3-Cluster (1983) et al. 3-Cluster (1998) Tamura et al (1998, 2000,2001) B(M1:3/2+ 1/2+) B(E2:5/2+ 1/2+) *eff.chrg: δe=0.15e ( 4.16*) ( 4.09*) B(E2:5/2+ 3/2+) B(E2:5/2+ all)/b(e2)c 1.0 assumed ΓB Rcd( 7 Li)/Rαd( 6 Li) Lifetime(5/2+) ps

34 4.3 Shell-model analyses of 89 Y(p+,K+) L 89 Y 34

35 Probe deep-lying Λ single-particle states 35

36 For [(0l n j n ) -1 (0l L j L )]J F.F becomes maximum at J=(bq) 2 /2 36

37 How to understand L 89 Y data (Hotchi et al, PRC64 (2001) in view of CAL(Motoba et al, 1988)

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41 3L and 3R peaks as a function of d

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43 Spin-spin and spin-orbit splitting at A=90

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

45 4.4 Theoretical prediction vs. Jlab experiment 28 Si(g,K+) L 28 Al and other predictions 45

46 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 46

47 Lab ds/dw for photoproduction (2Lab) Spin-flip interaction are dominant 47

48 4.4a Single-j model for the 28 Si target A typical example of medium-heavy target : 28 Si: (d ) 6 ) 5/2 to show characteristics of the (g,k + ) reaction with DDHF w.f. ( Spin-orbit splitting: consistent with L7 Li, 9 Be, 13 C, 89 Y ) 48

49 Theor. x-section for (d 5/2 ) 6 (g,k + ) [ j h -j L ]J 49

50 4-4b. Realistic prediction for 28 Si (g,k + ) L 28 Al By fully taking account of -- full p(sd) 6.n(sd) 6 configurations, -- fragmentations when a proton is converted, Al core nuclear excitation -- K + wave distortion effects Comparison with the 28 Si (e,e K + ) exp. 50

51 proton-state fragmentations should be taken into account to be realistic 51

52 Proton pickup from 28 Si(0 + ):(sd) 6 =(d 5/2 ) 4.1 (1s 1/2 ) 0.9 (d 3/2 )

53 Peaks can be classified by the characters 53

54 Exp. data: Fujii et al, Proc. SNP12 workshop (2012) Great progress when compared with cf. 28 Si(pi+,K+) 54

55 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) 55

56 40 Ca ( LS-closed shell case): high-spin states with natural-parity (2 +,3 -,4 + ) 56

57 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) G=0.75 MeV Hall A (bottom), J.J. LeRose et al. N.P. A804 (2008) 116. G=0.67 MeV 57

58 Theor. vs. Exp. Test of elem. Ampli. 58

59 Possible test of gp->lk ampl. (From P. Bydzovsky ) 59

60 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. 60

61 Life of strange many-body systems 61

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63 Thank you for your attention. 63