Study of light hypernuclei by the (e,e’K + ) reaction Graduate school of science, Tohoku Univ. Toshiyuki Gogami JLab E collaboration, 2009, JLab Hall-C 1

Contents (e,e’K + ) spectroscopic experiment in JLab – 7 Λ He, 9 Λ Li, 10 Λ Be, 16 Λ N, 12 Λ B, 28 Λ Al, 52 Λ V Precision light Λ hypernuclear spectroscopy – 7 Λ He (preliminary result) ΛN charge symmetry breaking APFB2011 in Korea (T.Gogami)2

Λ hypernuclear spectroscopy Updated from: O. Hashimoto and H. Tamura, Prog. Part. Nucl. Phys. 57 (2006)  V 3

Spectroscopic experiment by (e,e’K + ) reaction p n γ*γ* Λ K+K+ e-e- e + p ➝ e’ + K + + Λ ee target nucleus Feynman diagram u u d u s s u d – p K+K+ Λ γ*γ* 1.Large Momentum transfer Λ can be bounded in deeper orbit 2.Λ’s spin at forward angle Spin flip ~ spin non-flip 3.Proton  Λ Absolute mass value calibration e’-Spectrometer K + -Spectrometer p e’ p K+ Missing Mass H HY APFB2011 in Korea (T.Gogami)4

JLab E experimental setup 2× [msr] 3 – 12 [deg] 2× [msr] 2 – 12 [deg] e + p → e’ + Λ + K + 7 Li, 9 Be, 10 B, 12 C, 52 Cr (e,e’K + ) experiment 1.Coincidence experiment (K + and e - ) 2.Small cross section ( ~100 [nb/sr] ) 1/ Energy resolution Sub MeV (FWHM) Primary beam High intensity  Thin target (~100 [mg/cm 2 ]) High quality APFB2011 in Korea (T.Gogami)5

JLab CEBAF ( Continuance Electron Beam Accelerator Facility ) (e,e’K + ) experiment 1.Coincidence experiment (K + and e - ) 2.Small cross section ( ~100 [nb/sr] ) 1/ Energy resolution sub MeV (FWHM) 100 [m] Requirements for accelerator 1.High duty factor (~100%) 2.High intensity ( >a few 10 μA ) 3.Small emittance ( ~2 [mm ・ μrad] ) Small ΔE/E ( <1×10 -4 ) CEBAF was unique facility before MAMI updated Experimental Hall 6

(e,e’K + ) experiment in JLab st generation exp. JLab E e’-spectrometer + K + -spectrometer 12 Λ B ~ 750 [keV] (FWHM) nd generation exp. JLab E e’-spec. Optimized configuration + HKS(K + ) 7 Λ He, 12 Λ B, 28 Λ Al ~ 600 [keV] (FWHM) rd generation exp. JLab E HES(e’) Optimized configuration + HKS(K + ) 7 Λ He, 9 Λ Li, 10 Λ Be, 12 Λ B, 52 Λ V ≤ 500 [keV] (FWHM) Proof of feasibility Establish exp. method Up to Medium heavy 2004 JLab E (K +, e + )-spectrometers + septum 9 Λ Li, 12 Λ B, 16 Λ N ~ 670 [keV] (FWHM) Hall-C Hall-A Avoid huge background at very forward angle APFB2011 in Korea (T.Gogami)7

Analysis status of E p(e,e’K + )Λ,Σ 0  HES-HKS basic system works well ~40 hours (5 shifts) JLab E p(e,e’K + )Λ,Σ 0 Very preliminary Analysis is in progress 1.Energy (mass) calibration 2.Developing new code for high multiplicity data Analysis is in progress 1.Energy (mass) calibration 2.Developing new code for high multiplicity data E.M background ∝ ~Z 2 Λ and Σ 0 can be seen at the same time rd generation exp. JLab E HES(e’) Optimized configuration + HKS(K + ) 7 Λ He, 9 Λ Li, 10 Λ Be, 12 Λ B, 52 Λ V ≤ 500 [keV] (FWHM) Up to Medium heavy Hall-C APFB2011 in Korea (T.Gogami)8

Experimental data of A=7 system Old 7 Λ He data ( M.Juric, NPB 52, 1973 ) -B  [MeV]  0.03  0.2 MeV from α  n n JLab E Li(e,e’K + ) 7 Λ He Compare to theoretical calculation Preliminary Four-body cluster model for T=1 iso-triplet hypernuclei (E.Hiyama et al., NPC 80, 2009) α + Λ + N + N APFB2011 in Korea (T.Gogami)9

Theoretical calculation of A=7 system Four-body cluster model for T=1 iso-triplet hypernuclei (E.Hiyama et al., NPC 80, 2009) α + Λ + N + N Old 7 Λ He data ( M.Juric, NPB 52, 1973 ) -B  [MeV]  0.03  0.2 MeV from α  n n JLab E Li(e,e’K + ) 7 Λ He Compare to theoretical calculation Preliminary 10

Theoretical calculation of A=7 system -B  (MeV)  0.03  0.2 MeV from α  n n Four-body cluster model for T=1 iso-triplet hypernuclei (E.Hiyama et al., PRC 80, 2009) α + Λ + N + N JLab E Li(e,e’K + ) 7 Λ He CSB interaction is determined to reproduce B Λ of 4 Λ H and 4 Λ He. Will be talked by E.Hiyama in Plenary 6 session(8/24) Decay pion spectroscopy Preliminary APFB2011 in Korea (T.Gogami)11

Summary (e,e’K + ) spectroscopic exp. in JLab – E (2000,Hall-C) 12 Λ B – E (2004,Hall-A) 9 Λ Li, 12 Λ B, 16 Λ N – E (2005,Hall-C) 7 Λ He, 12 Λ B, 28 Λ Al – E (2009,Hall-C) 7 Λ He, 9 Λ Li, 10 Λ Be, 12 Λ B, 52 Λ V Precision light Λ hypernuclear spectroscopy – 7 Λ He (preliminary result by E01-011) – 10 Λ Be (analyzing) Analysis stage Final analysis stage ΛN charge symmetry breaking APFB2011 in Korea (T.Gogami)12

APFB2011 in Korea (T.Gogami)13 End Thank you very much