Study of Lambda hypernuclei with electron beams

Transcription

1 Study of Lambda hypernuclei with electron beams Satoshi N Nakamura, Tohoku University JLab HKS-HES Mainz A1 hypernuclear Collaborations JLab E collaboration, 2009, JLab Hall-C

2 Quantum Many-body System bound by the Strong Int. Baryon (Hyper) Nucleus Neutron Star Pictures from H.Ohnishi m 10 4 m Spectroscopy of Hypernuclei NN scat. LQCD Baryon Interaction Obs. 2 M Hyperon Puzzle

3 Lattice QCD Modarn baryon Interaction models QCD Nuclear Force Lots of NN scattering data Baryon Interaction Quark degree of freedom SU f (3) Symmetry Hyperon Force Limited YN/YY scattering data Established Calculation Tech. Cluster Model Shell Model Mean Field Nuclear Structure Normal/Exotic nuclei Nuclear Structure Hypernuclei

4 Production of Hypernuclei s-quark exchange s,sbar pair creation (K -,π - ) (π +,K + ), (e,e K + )

5 Characteristics of (e,e K) HY study Electromagnetic production Convert Proton to Lambda : Mirror to well studied HY by (π,k), (K, π) Absolute energy calibration with p(e,e K + ), Σ 0 High quality primary beam High energy resolution (< 1MeV) Thin enriched target

6 Challenge of (e,e K) HY Study Huge e Background due to Bremsstrahlung and Mφller scattering Signal/Noise, Detector Less Hypernuclear Cross Section Coincidence Measurement (e, K + ) Limited Statistics DC beam is necessary High Quality Electron Beam is Essential!

7 Three generation experiments at Hall-C E (2000) : Existing spectrometers, SOS + Enge Proof of Principle E (2005) : Construction of HKS, Tilt Method, Σ 0, 7 He, 12 B, 28 Al Light Hypernuclei E (2009) : HKS+HES, new Beamline, Splitter, Σ 0, 7 He, 12 B, 52 V Light to medium-heavy Hypernuclei

8 Facilities for (e,e K + ) HY study HES HKS JLab Hall-A HRS+HRS (2004) JLab Hall-C HNSS (2000) HKS (2005) HKS+HES (2009) Mainz MAMI-C A1 KaoS (2008-)

9 JLab E (Hall-C) setup Pre-chicane beam line θ e = 6.5 ± 5.0 deg. 7.0 msr θ K = 5.7 ± 4.6 deg. 8.5 msr P K, P e : mmmmmmm E e, m A : kkkkk Δp/p ~ m HH : ddddddd aa MMMMMMM MMMM

10 JLab E (Hall-C) setup

11 p(e,e K + ), Σ 0 : Elementary Process Jlab E KaoS 2008 P.Achenbach et al. Jlab E Jlab E05-115

12 12 C(e,e K + ) 12 B 0.54 MeV (FWHM) Absolute MM calibration 0.71 MeV (FWHM) L.Tang, C.Chen, T.Gogami et al. Phys. Rev. C 90 (2014) C(π +,K + ) 12 C KEK-PS E MeV (FWHM) 12 C gs energy from emulsion

13 12 C emulsion data 11 C (3/2-) : Ex = 4.8MeV Statistical error only Reference for all (π, K) B data: B ( 12 Cg.s.) = MeV

14 12 B emulsion data (# of events) B ( 12 Bg.s.) = MeV Emulsion Result (M.Juric et al.) B ( 12 Bg.s.) = (stat) MeV (JLab E05-115) Totally independent measurement

15 Possible shift of 12 C gs B B(emulsion)-B (π,k) [MeV] T. Gogami, Doctor thesis, (2014) Tohoku U.

16 Charge Symmetry Breaking Effect of N interaction B ( 4 + H,1 ) = 1.00 ± 0.06 MeV MeV B ( 4 + He,1 ) = 1.24 ± 0.06 MeV B ( 4 + H,0 ) = 2.04 ± 0.04 MeV n n p 0.35 MeV 0 + B ( 4 + He,0 ) = 2.39 ± 0.03 MeV 4 H 4 He p n p Coulomb effect is small. Charge Symmetry Breaking cf) B( 3 H)-B( 3 He)- B c = = 71 kev

17 Three-body NN force Modern ChPT-NLO calculation predicts 3NF effect is < 100keV but NLO calculation cannot explain experimental results for A=4, T=1/2, hypernuclei. (Nogga, HYP2012) π Σ π N N Σ mass difference ~ 80 MeV < N mass difference ~ 300MeV M(Σ + ) < Μ(Σ 0 ) < Μ(Σ ), Μ(Σ Σ + ) 8MeV Consistent understanding of 0 +, 1 + of 4 H, 4 He Phenomenological potential : A.R.Bodmer&Q.N.Usmani, PRC 31(1985)1400.

18 B of light hypermultiplets 4 H 4 He B n B n ( 4 H) = 2.04 ± 0.04 MeV n p p p Experimental B 67 events ( 4 He) = 2.39 ± 0.03 MeV 98 events CSB Hiyama et al. PRC PTP 128 (2012) He 7 Li* 7 Be n α p n α α B ( B n 7 p p No reported B * Li ) = 5.26 ± 0.03 MeV 167 events ( 7 Be) = 5.16 ± 0.08 MeV 15 events Exp. Data : Emulsion 10 Be B 10 B ( B 7 * Li ) = 9.11± 0.22 MeV α n α α p α 3 event ( 10 B) = 8.89 ± 0.12 MeV 10 events

19 7 He = 6 He + behaves like glue 6 He : 2n halo E.Hiyama et al. PRC 80, (2009)

20 7 He Density Distributions 2n α α n n

21 7 He spectrum Juric et al., Nucl. Phys. A484 (1988) 520 No B was obtained.

22 7 He spectrum of E01-01 SNN et al., PRL 110, (2013) Preliminary E01-011(HKS) 90 counts

23 7 He spectrum of E T.Gogami, Doctor Thesis (2014) Tohoku Univ. Preliminary E01-011(HKS) 90 counts E05-115(HKS-HES) >500 counts

24 CSB interaction test in A=7 iso-triplet comparison SNN et al., PRL 110, (2013) E (2005) Assumed CSB potential may be too naïve. New measurements on A=4 systems are necessary. E (2009) T.Gogami, Doctor Thesis (2014) Tohoku Univ.

25 CSB interaction test in A=7 iso-triplet comparison E (2005) E (3/2 +,5/2 + ) [MeV] E.Hiyama et al., PRC 80, (2009) M.Sotona et al., PTP 117 (1994) E (2009) D.J.Millener Private Comm. (2013) T.Gogami, Doctor Thesis (2014) Tohoku Univ.

26 10 B(e,e K + ) 10 Be +

27 10 B and 10 Be T.Gogami, Doctor Thesis (2014) Tohoku Univ.

28 Comparison of the ground states (A=10) CSB(even) on : 20 kev CSB off: -180 kev

29 A=4 system CSB N potential Σ N N? B ( 4 + H,1 ) = 1.00 ± 0.06 MeV MeV B ( 4 + He,1 ) = 1.24 ± 0.06 MeV B ( 4 + H,0 ) = 2.04 ± 0.04 MeV n n p 0.35 MeV 0 + B ( 4 + He,0 ) = 2.39 ± 0.03 MeV n p p Coulomb effect is very small. A.R.Bodmer&Q.N.Usmani, PRC 31(1985)1400.

30 4 H, 4 He emulsion data Emulsion Result (M.Juric et al.) (# of events) B (MeV) 2.14 ± ± 0.12 CCC = 0.35 MMM Δ = 0.22 MMM

31 A=4 system CSB N potential Σ N N? B ( 4 + H,1 ) = 1.00 ± 0.06 MeV 1 + B ( 4 + He,1 ) = 1.24 ± 0.06 MeV 0.24 MeV 4 He(e,e K + ) 4 H(1 + ) J-PARC B ( 4 + H,0 ) = 2.04 ± 0.04 MeV Decay π n n p 0.35 MeV 0 + E13 B ( 4 + He,0 ) = 2.39 ± 0.03 MeV n p p Coulomb effect is very small. A.R.Bodmer&Q.N.Usmani, PRC 31(1985)1400.

32 Future Plans at JLab

33 Possible Future JLab & MAMI 1. Elementary, Σ 0 Reliable data 1 H(e,e K + ), Σ 0 in low Q 2 2. Few-body 2 d(e,e K + ) [N], 3 t(e,e K)[nn] Exotic bound state, N int. 4 He(e,e K + ) 4 Η(1 + ) N CSB 3. Medium-heavy 4. Heavy 6,7 Li(e,e K) 6 He, 7 He 19 F(e,e K) 19 O 40,44,48 Ca(e,e K + ) 40,44,48 K s S.E., iso-spin 27 Al(e,e K + ) 27 Mg Tri-axial deformation 208 Pb(e,e K + ) 208 Tl in heaviest nucleus 5. Decay π Weak decay of light hyper-fragments

34 Few-body physics with strangeness Search of [n] bound state and study of n- interaction through FSI. Established lightest hypernyclei = 3 H Hyp-HI experiment at GSI a structure in d + π -, t + π - invariant mass T.R.Saito, NUFRA2011 Indication of a n, nn bound state? 2 d(e,e K + )[n] 3 t(e,e K + )[nn] Direct method to search these exotic systems. C.Rappold et al. PRC88, (R) (2013)

35 27 Al (e,e K + ) 27 Mg 9 Be = α + α + Genuine hypernuclear state M.Isaka Tri-axially deformed 26 Mg core + in p-shell Totally new method to study shape of nucleus with!

36 General tendency is well understood. s p d f g Lines: Calc. by Yamamoto & Rijken

37 Furumoto, Sakuragi, Yamamoto, PRC 79 (2009) (R) To solve hyperon puzzle Microscopic nuclear force ρ 0 2 ρ 0 3/4BF Density dependence with hyperons Importance of 3B/4BF

38 Yamamoto & Rijken + 3B/4B repulsion in NNN only Yamamoto & Rijken

39 General tendency understood. Need more precise data. s p d f g Lines: Calc. by Yamamoto & Rijken

40 Mass dependence of B Mpa

41 Mass dependence of B Important to have precise spectroscopy in wide mass range (A=50 208) Mpa

42 Present Status of Hypernuclear Spectroscopy (2011) (2014) 52 V 6 H Updated from: O. Hashimoto and H. Tamura, Prog. Part. Nucl. Phys. 57 (2006) 564.

43 Summary We have been developing large magnetic spectrometers (HKS, HES) and techniques in the last decade at JLab and (e,e K + ) HY spectroscopy is now established. Best spectroscopy of 12 B was performed and absolute binding energy calibration implies a shift ( kev) of 12 C emulsion B which is the reference to all (π +,K + ) spectrosopy binding energies. Binding energy of 7 He gs was determined. Important input for N CSB potential. Excited state of 7 He was clearly observed. New data on 10 Be gs was obtained. We are designing next programs at JLab. systematic study of B for wide A range up to 208, tri-axial deformed HY, CSB study with light HY and elementary study with exotics (nn).

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45 , Σ 0 from polyethylene ( CH 2 )target

46 , Σ 0 from CH 2 target p(e,e K + ) JLab E CH 2, ~ 450 [mg/cm 2 ] ~ 2.0 [μa] ~ 38 [hours] p(e,e K + )Σ 0