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Recent Progress in Hypernuclear Physics

Recent Progress in Hypernuclear Physics. E. Hiyama (Nara Women ’ s Univ.). Hypernuclear physics has recently become very exciting owing to new epoch-making experimental data. The recent progress in hypernuclear physics from a theorist’s viewpoint of hypenuclear structure.

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Recent Progress in Hypernuclear Physics

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  1. Recent Progress in Hypernuclear Physics E. Hiyama (Nara Women’s Univ.) Hypernuclear physics has recently become very exciting owing to new epoch-making experimental data. The recent progress in hypernuclear physics from a theorist’s viewpoint of hypenuclear structure.

  2. Nuclear chart with strangeness Multi-strangeness system such as Neutron star Λ Λ Outline 1. Introduction 2. S=-1 hypernuclei and YN interactions 3. S=-2 hypernuclei and YY interactions 4. Future subjects 5. Concluding remarks

  3. 1. Introduction

  4. Major goals of hypernuclear physics 1) To understand baryon-baryon interactions Fundamental and important for the study of nuclear physics 2) To study the structure of multi-strangeness systems To understand the baryon-baryon interaction,two-body scattering experiment is most useful. Total number of Nucleon (N) -Nucleon (N) data: 4,000 YN and YY potential models so far proposed (ex. Nijmegen, Julich, Kyoto-Niigata) have large ambiguity. ・Total number of differential cross section Hyperon (Y) -Nucleon (N) data: 40 ・NOYY scattering data

  5. Therefore, as a substitute for the 2-body limited YN and non-existent YY scattering data, the systematic investigation of light hypernuclear structure is essential .

  6. Strategy to determine YN and YY interactions from the studies of light hypernuclear structure YN and YY interactions based on meson theory:Nijmegen, Ehime, Julich・・ based on constituent quark model:Kyoto-Niigata,・・ using a few-body method My role ① ③ Use Suggest to improve Accurate calculation of hypernuclear structure Few-body, cluster model, shell model, ….. Compare theoretical results with experimental data X ② No direct information Spectroscopy experiments 　　・ High-resolution γ-ray spectroscopy experiment by Tamura and his collaborators ・ Emulsion experiment by Nakazawa and his collaborators

  7. Our few-body caluclational method Gaussian Expansion Method (GEM) , since 1987 , ・A variational method using Gaussian basis functions ・Take all the sets of Jacobi coordinates Developed by Kyushu Univ. Group, Kamimura and his collaborators. Review article : E. Hiyama, M. Kamimura and Y. Kino, Prog. Part. Nucl. Phys. 51 (2003), 223. High-precision calculationsof various 3- and 4-body systems: Exotic atoms / molecules , 3- and 4-nucleon systems, Multi-cluster structure of light nuclei, Light hypernuclei, 3-quark systems, ………. An example of accuracy of the method:

  8. Benchmark-test calculation of the 4-nucleon bound state PRC64, 044001(2001) 4He 1. Faddeev-Yakubovski (Kamada et al.) 2. Gaussian Expansion Method (Kamimura and Hiyama) 3. Stochastic varitional (Varga et al.) 4. Hyperspherical variational (Viviani et al.) 5. Green Function Variational Monte Carlo (Carlson at al.) 6. Non-Core shell model (Navratil et al.) 7. Effective Interaction Hypershperical Harmonics (Barnea et al.) n n p p 4-nucleon bound state NN:AV8 Good agreement among the 7 different method in the binding energy, r.m.s. radius and two-body correlation function

  9. Our few-body calculational method (GEM) New possibilities Advantage It becomes possible to study spatially, highly-excited states in few-body systems. ・Function space of the few-body Gaussian basis functions is so wide that they construct a complete set in a finite region. It becomes possible to study resonant and non-resonant continuum states of few-body systems in these cases. ・In some cases, it is not difficult to impose scattering boundary condition on the total few-body wavefunction using a Kohn-type variational principle. A good example:

  10. Example of application of our method “ Five-body calculation of resonace and scattering states of pentaquark systems “ E. Hiyama, M. Kamimura, a. Hosaka, H. Toki and Y. Yahiro, Phys. Letters B633 (2006) 237. Scattering problem of the uudds system,in the constituent quark model, was solved for the first time. NK scattering phase shift including 5-body configurations in the finite region No resonance in the energy region of the reported pentaquark. N K q q q q q s + + q q q s

  11. Strategy to determine YN and YY nteractions from the studies of light hypernuclear structure YN and YY interactions based on meson theory: Nijmegen, Ehime, Julich・・ based on constituent quark model:Kyoto-Niigata,・・ ① ③ Use Suggest to improve Accurate calculation of hypernuclear structure Few-body, cluster model, shell model, ….. 2. S=-1 hypernuclei and YN interaction 3. S=-2 hypernuclei and YY interaction Compare theoretical results with experimental data ② Spectroscopy experiments 　　・ High-resolution γ-ray spectroscopy experiment by Tamura and his collaborators ・ Emulsion experiment by Nakazawa and his collaborators

  12. 2. S= -1 hypernuclei andYN interaction

  13. One of the important issues ΛN interaction(effectively including ΛN -ΣN coupling) Almost determined since 1998 ----- SLS (Symmetric LS) ----- ALS (Anti symmetric LS)

  14. YN LS force and energy-splitting in 9Be and 13C Λ Λ Λ Λ ----- SLS (Symmetric LS) 12C 8Be 9Be ----- ALS (Antisymmetric LS) 13C Λ Λ [vanishes in S=0 nuclei, Pauli] [breaks charge symmetry] In the ALS part : 0 < VALS(meson theory) VALS (constituent quark model) << Kyoto-Niijata FSS potential Nijgemen model D, F , soft core ’97a-f

  15. BNL-E929 BNL-E930 1/2- (0p) Λ (0s) ΔE Λ 3/2- 3/2+ ΔE LS splitting γ γ 2+ 5/2+ γ γ 0+ 1/2+ 0+ 1/2+ 12C 13C 8Be 9Be Λ Λ 3- and 4-body calculations: E. Hiyama, M. Kamimura, T. Motoba, T. Yamada and Y. Yamamoto Phys. Rev. Lett. 85 (2000) 270. Λ α Λ 13C 9Be α α Λ Λ α α YN LS force 1) Meson theory : Nijmegen Model D, F, soft core’97 a – f. 2) Qurak model : Kyoto-Niigata, FSS

  16. H. Akikawa et al. Phys. Rev. Lett. 88 (2002) 082501; H. Tamura et al. Nucl. Phys. A754 (2005) 58c BNL-E930 35 40 keV 3/2+ 3/2+ ～ 5/2+ 5/2+ 43±5 Quark EXP keV BNL-E929 150 200 keV 1/2- 1/2- ～ 3/2- 3/2- 152 54 36 keV EXP ± ± Quark S.Ajimura et al. Phys. Rev. Lett. 86,(2001) 4255 ΛN LS force and 9Be and 13C Λ Λ 9Be Λ 3/2+ 80 200 keV ～ 5/2+ Meson Nijmegen model D,F Soft core ’97a-f 13C Λ 1/2- 360 960 keV ～ 3/2- Meson

  17. We suggested that there are 2 paths to improve the Meson models : ・ reduce the SLS strength ・ enhance the ALS strength so as to reproduce the observed LS splittings in 9Be and 13C. LS splitting in9Be Λ Meson Theory (Large) (Small) SLS SLS +ALS 5/2+ 5/2+ Λ Λ 80～200 keV 140～250 keV 3/2+ 3/2+ 5/2+ 3/2+ Exp. 43±5 keV (Large) - (Large) SLS + ALS 5/2+ Λ 35～40keV 3/2+ α α Quark-based 9Be Λ

  18. LS splitting in 9Be Λ Recently, a new YN interaction based on meson theory, extended soft core potential 06 (ESC06) by Th. A Rijken 9Be Hiyama (2007) (reduced) Λ BNL-E930 (small) SLS SLS + ALS 3/2+ 3/2+ 98 keV 5/2+ 39 keV 5/2+ keV EXP 43±5 ESC06 Good agreement H. Akikawa et al. Phys. Rev. Lett. 88,(2002)82501; H. Tamura et al. Nucl. Phys. A754,58c(2005)

  19. Strategy to determine YN and YY interactions from the studies of light hypernuclear structure Meson theory :Nijmegen Quark model :Kyoto-Niigata YN SLS+ALS potentials ① ③ ④ new version potential (ESC06) Use Suggest to improve Accurate calculation of energy splitting (9Be and 13C) using the YN SLS+ALS potentials Λ Λ comparison again: good agreement ⑤ ② comparison Spectroscopy experiments High-resolution γ-ray spectroscopy experiment in 9Be and 13C by Tamura and his collaborators by Kishimoto and his collaborators Λ Λ

  20. Hypernuclear g-ray data since 1998 ・Millener (p-shell model), ・Hiyama (few-body)

  21. 3. S=-2 hypernuclei andYY interaction

  22. What is the structure when one or more Λs are added to a nucleus? + + + + ・・・・ Λ Λ Λ Λ Λ It is conjectured that extreme limit, which includes many Λs in nuclear matter, is the core of a neutron star. nucleus In this meaning, the sector of S=-2 nuclei , double Λhypernuclei and Ξhypernuclei is just the entrance to the multi-strangeness world. However, we have hardly any knowledge of the YY interaction because there exist no YY scattering data. Then, in order to understand the YY interaction, it is crucial to study the structure of double Λhypernuclei and Ξ hypernuclei.

  23. Recently, the epoch-making data has been reported by the KEK-E373 experiment. Observation of 6He ΛΛ Uniquely identified without ambiguity forthe first time α+Λ+Λ Λ Λ α 7.25 ±0.1 MeV 0+ NAGARA event

  24. Strategy of how to determine YN and YY interactions from the study of light hypernuclear structure YY interaction Nijmegen model D 6He ① Suggest reducing the strength of spin-independent force by half use ③ ΛΛ Λ Λ Accurate structure calculation α compare between the theoretical result and the experimental dataof the biding energy of 6He ② prediction of new double Λ hypernuclei ④ ΛΛ Spectroscopic experiments Emulsion experiment (KEK-E373) by Nakazawa and his collaborators

  25. My theoretical contribution using few-body calculation Approved proposal at J-PARC ・E07 “Systematic Study of double strangness systems at J-PARC” by Nakazawa and his collaborators It is difficult to determine 1) spin-parity 2) whether the observed state is the ground state or an excited state comparison Emulsion experiment Theoretical calculation input:ΛΛ interaction to reproduce the observed binding energy of 6He ΛΛ identification of the state

  26. Successful example to determine spin-parity of double Λhypernucleus --- Demachi-Yanagi event for 10Be ΛΛ Observationof 10Be --- KEK-E373 experiment ΛΛ Λ Λ 8Be +Λ+Λ α α +0.35 12.33 MeV -0.21 10Be ground state ? excited state ? ΛΛ 10Be ΛΛ Demachi-Yanagi event

  27. 4-body calculation of 10Be (Deamchi-Yanagi event) ΛΛ E. Hiyama, M. Kamimura, T. Motoba, T.Yamada and Y. Yamamoto Phys. Rev. C66, 024007 (2002) VΛΛ To reproduce theobserved binding energy of 6He Λ ΛΛ Λ α+Λ+Λ α α 7.25 ±0.1 MeV The binding energies of all the subsystems in 10Be are reproduced . ΛΛ Λ Λ α Λ Λ Λ Λ α α α α

  28. Successful interplitation of spin-parity of Λ Λ α α E. Hiyama, M. Kamimura,T.Motoba, T. Yamada and Y. Yamamoto Phys. Rev. 66 (2002) , 024007 In this way, we succeeded in interpreting the spin-parity by comparing the experimental data and our theoretical calculation. Demachi-Yanagi event

  29. 4-body model of p-shell double Λ hypernuclei Therefore, the 4-body calculation has predictive power. Hoping to observe newdouble Λ hypernuclei in future experiments, I have predicted level structures of thesedouble Λ hypernuclei within the framework of the α+ x + Λ+Λ4-body model. E. Hiyama, M. Kamimura, T. Motoba, T.Yamada and Y. Yamamoto Phys. Rev. C66, 024007 (2002) Λ x Λ α x t 3He = n p d = = = = = 7Li 8Li 8Li 7He 9Be ΛΛ ΛΛ ΛΛ ΛΛ ΛΛ

  30. Spectroscopy of ΛΛ-hypernuclei E. Hiyama, M. Kamimura,T.Motoba, T. Yamada and Y. Yamamoto Phys. Rev. 66 (2002) , 024007 By comparing this theoretical predictionand future experimental data, we can interpret the spectroscopy of those double Λ hypernuclei.

  31. 4. Future subjects

  32. In S=-1 sector, what are the open questions inYN interaction? • Charge symmetry breaking • (2) ΛN－ΣN coupling (1) E13 at J-PARC “γ-ray spectroscopy of light hypernuclei” by Tamura and his collaborators Day-1 experiment Parallel session ( E3-1 ) 6th June, 14:30～ Room:G510 11B 4He Λ Λ (2) E10 at J-PARC “Study on Λ-hypernuclei with the double Charge-Exchange reaction” by Sakaguchi , Fukuda and his collaboratiors 6H 9He Λ Λ

  33. In S=-2 sector, the most important subjects still to be studied • ΛΛ－ΞN coupling • (2)ΞN -ΞN interaction I shall introduce above two subjects.

  34. (1) ΛΛ－ΞN coupling One of the major goals in hypernuclear physics : To study structure of multi-strangeness systems (extreme limit : neutron star) N N N Multi-strangeness systems N N N N Λ Λ Λ ΞN Λ Λ 25MeV ΛΛ Threshold energy difference is very small ! It is considered that ΛΛ→ΞN particle conversion is strong in multi-strangeness systems.

  35. Effect of ΛΛ－ΞN coupling is small in 6He which was observed as NAGARAevent. ΛΛ Pauli Forbidden V ΛΛ--ΞN P3/2 Ξ- Λ Λ n n p p p S1/2 (3 protons inS1/2) 6He ΛΛ ・I.R. Afnan and B.F. Gibson, Phys. Rev. C67, 017001 (2003). ・Khin Swe Myint, S. Shinmura and Y. Akaishi, nucl-th/029090. ・T. Yamada and C. Nakamoto, Phys. Rev.C62, 034319 (2000).

  36. For the study of ΛΛ－ΞN coupling interaction, s-shell double Λ hypernuclei such as 4H and 5H ( 5He) are very suitable. ΛΛ ΛΛ ΛΛ Λ Λ Λ Λ 4H 5H ( 5He) ΛΛ n n p p ΛΛ ΛΛ n ・I.N. Filikhin and A. Gal, Phys. Rev. Lett. 89, 172502(2002) ・Khin Swe Myint, S. Shinmura and Y. Akaishi, Eur. Phys. J.A16, 21(2003). ・D. E. Lanscoy and Y. Yamamoto, Phys. Rev. C69, 014303(2004). ・H. Nemura, S. Shinmura, Y. Akaishi and Khin Swe Myint, Phys. Rev. Lett. 94, 202502 (2005).

  37. 5H Λ Λ ΛΛ n p n V ΛΛ－ΞN P3/2 Ξ- Λ Λ n n p p S1/2 5H (2 protons inS1/2) ΛΛ Due to NO Pauli plocking, the ΛΛ－ΞN coupling can be large in 5H ΛΛ B.F. Gibson, I.R. Afnan, J.A.Carlson and D.R.Lehman, Prog. Theor. Phys. Suppl. 117, 339 (1994).

  38. In this way, the study of structure of s-shell double Λ hypernuclei is important for the study of ΛΛーΞN coupling. The detailed studies will be reported by ・D. Lanskoy ( E3-7 ) ・Y. Yamamoto ( E4-2 ) ・H. Nemura ( E4-5 ) 6th June, afternoon, 14:30 ～18:30 “Hyperon Interactions and Hypernuclear Physics” Room: G510

  39. In S=-2 fields, the most important subjects to be still studied (2) ΞN -ΞN interaction Ξ Ξ hypernucleus nucleus For the study of ΞN interaction, it is important to study the structure of Ξ hypernuclei. However, so far there was no observed Ξ hypernuclei. Then, it is important to predict theoretically what kinds of Ξ hypernuclei will exist as bound states.

  40. For this purpose, recently, I studied these Ξhypernuclei. p n n p n p α Ξ- Ξ- Ξ- (５Li+Ξ-) (d+Ξ-) (t +Ξ-)- ( Ξ- t - n n Ξ- n α α α α α Ξ- (9Be+Ξ-) (6He+Ξ-) (11B+Ξ-) (ESC04) ΞN interaction to reproduce the experimental data of 12C(K-,K+) reaction ・T. Fukuda et al. Phys. Rev. C58, 1306, (1998); 　　 ・P.Khaustov et al. Phys. Rev. C61, 054603 (2000).

  41. Spectroscopy of Ξ hypernuclei at J-PARC Ξ- n Ξ- t n p n n n n n α p Ξ- Ξ- α α α Ξ- Ξ- α α MeV (pn+Ξ ) (pnn+Ξ ) (5He+Ξ) (6He+Ξ) ( ９B e+Ξ) (11B+Ξ) 0 -2 d+Ξ αn+Ξ 1/2 + -5 (α+Ξ)+nn 1- 1/2+ t +Ξ (8Be+Ξ)+n -10 2- 11B+Ξ 1+ 0+ 2- 1- -20 1- 2-

  42. Approved proposal at J-PARC ・E05 “Spectroscopic study of Ξ-Hypernucleus, 12Be, via the 12C(K-,K+) Reaction” by Nagaeand his collaborators Day-1 experiment K+ K- p Ξ- 11B 11B 12C Ξ hypernucleus First observation of Ξ hypernucleus This observation will give information about ΞNinteraction.

  43. Spectroscopy of Ξ hypernuclei at J-PARC Ξ- n Ξ- t n p n n n n n α p Ξ- Ξ- α α α Ξ- Ξ- α α MeV (pn +Ξ) (pnn+Ξ) (5He+Ξ) (6He+Ξ) ( ９Be+Ξ) (11B+Ξ ) 0 -2 d+Ξ αn+Ξ 1/2 + -5 (α+Ξ)+nn 1- 1/2+ t +Ξ (8Be+Ξ) +n -10 2- 11B+ Ξ 1+ 0+ 2- 1- -20 1- 2-

  44. Concluding remark Multi-strangeness system such as Neutron star GSI JLAB DAΨN E J-PARC J-PARC

  45. At the end of next year (2008), the first beam in the main ring will appear at J-PARC. And, it is planned to perform the first experiment on hypernuclei in early 2009. So, it is expected that all hypernuclear experimentalists may be very busy. If man-power for such experiments is not enough, I am ready to join those experiments.

  46. In 2002, KEK-E509, I had 7 shifts for this experiment. Film badge

  47. New film badge 01 / 2009 I shall be happy if I could join the future experiments at J-PARC facility with this new film badge.

  48. Thank you!

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