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Hyperons in nuclei -- review

Hadron2011 June 17, 2011 Munich. Hyperons in nuclei -- review. Dept. of Physics, Tohoku University H. Tamura. 1. Introduction 2. L hypernuclei 2.1 ( p ,K + ) spectroscopy (incl. n-rich L hypernuclei) 2.2 g spectroscopy of L hypernuclei

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Hyperons in nuclei -- review

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  1. Hadron2011 June 17, 2011 Munich Hyperons in nuclei -- review Dept. of Physics, Tohoku University H. Tamura

  2. 1. Introduction • 2. L hypernuclei • 2.1 (p,K+) spectroscopy (incl. n-rich L hypernuclei) • 2.2 g spectroscopy of L hypernuclei • 2.2. (e,e’K+) spectroscopy of L hypernuclei • 3. S-nuclear systems • 4. Double strange systems • 5. Weak decays of L hypernuclei (FINUDA data) • 6. Summary • K mesons in nuclei (K- nucleus and K- atoms) Contents

  3. 1. Introduction

  4. Nu ~ Nd ~ Ns Strangeness in neutron stars ( r > 3 - 4 r0 ) Strange hadronic matter (A →∞) Strangeness LL, X Hypernuclei Z L, S Hypernuclei -2 N -1 0 World of matter made of u, d, s quarks “Stable” Higher density => Baryon-baryon interactions Unified understanding of “extended nuclear force” Understanding of short range parts of nuclear force Test of lattice QCD ３-dimensional nuclear chart by M. Kaneta inspired by HYP06 conference poster

  5. Nu ~ Nd ~ Ns One probable assumption but should be determined by experimets. r0 n star High density matter in neutron stars Large neutron Fermi energy -> Hyperons appear Baryon fraction: sensitive to YN, YY interactions -> Maximum mass, Cooling speed Hypernuclear data -> realistic calculations possible We still need XN, LL, SN, KN forces, LN p-wave force, NNN and YNN force, … - Vela Supernova remnant The heavy n-star (M=1.97 ± 0.04 M◎) can be supported? S’s appear? Kbar appear? Strange hadronic matter exists?

  6. Overview of Strangeness Nuclear Physics Experiments • K- or p+/- beams KEK-PS, BNL-AGS => J-PARC L and S hypernuclear spectroscopy, g-spectroscopy of L hypernuclei LL and X hypernuclei [Takahashi], weak decays of L hypernuclei K- nuclei [Fujioka], K- atoms, • e- beam Jefferson Lab (Hall A, Hall C), MAMI-C high-res. Lhypernuclear spectroscopy, weak decays • K- from f DAFNE (FINUDA, SIDDHARTA, AMADEUS) spectroscopy of L hypernuclei [Botta,Bonomi] weak decays of L hypernuclei [Bufalino] K- nuclei, K- atoms [Ishiwatari,Okada], • Heavy ion beams GSI (HypHI) Heavy-Ion induced production, lifetimes,.…

  7. 2. L hypernuclei 2.1 (p+,K+) spectroscopyincl. n-rich L hypernuclei

  8. Previous (p+,K+) data and LN interaction SKS at KEK-PS p+ n -> L K+ -> Nuclear potential of L UL = - 30 MeV(c.f. UN = -50 MeV) Better resolution is necessary forLN spin-dependent forces, LN-SN force, .. (p,K+) -> (e,e’K+)at JLab g spectroscopy at KEK/BNL, J-PARC Mass of hypernucleus -BL (MeV) Hotchi et al., PRC 64 (2001) 044302

  9. (2006) Present Status of L Hypernuclear Spectroscopy Updated from: O. Hashimoto and H. Tamura, Prog. Part. Nucl. Phys. 57 (2006) 564.

  10. Akaishi et al., PRL 84 (2000) 3539 p- p p -> L n K+ Neutron-rich hypernuclei 2-step charge exchange (p-p->p0n, p0p->K+L etc.) Via S- admixture in L hyp. (p- p->S- K+, S- p<->Ln) pp~1.2 GeV/c 11.1±1.9 nb/sr 10B (p-, K+) 10LLi Physics Interest • L-S coherent coupling -> LNN attraction important in neutron stars • Cross section sensitive to S- admixture in L hyp. • n-halo disappear by L ? Almost no background KEK E521, K6+SKS Saha et al., PRL 94 (2005) 052502 First data on n-rich hypernucleus New data from FINUDA – 6LH suggested by 6Li(K-stop,p+) E. Botta, Monday

  11. 2.2 g spectroscopy

  12. Hyperball1998~ Ge array for hypernuclei Hypernuclear g-ray data CERN (NaI) (p+,K+ g) at KEK-PS (K-, p- g) at BNL-AGS => DE ~ 2 MeV -> 3 keV (FWHM) Observation of hypernuclear fine structure LN spin-dependent interaction Nuclear shrinkage by a L from B(E2)

  13. D =∫V (r) |u(r)|2 r2dr, r = r -r sL pN • Two-body LN effective interaction Level spacing: Linear combination of D, SL, SN, T s - - V p-shell: 5 radial integrals for sL pN w.f. LN spin-dependent interactions • Low-lying levels of L hypernuclei Millener’s approach D SL SN T Well known from UL = - 30 MeV g-ray data => D = 0.33 (0.43 for A=7), SL = -0.01, SN= -0.4, T= 0.03 [MeV] Small spin-dependent forces have been established.

  14. Revised SL = -0.01 MeV T = 0.03 MeV Observation of “Hypernuclear Fine Structure”BNL E930(AGS D6 line + Hyperball) 9Be (K-, p- g) 9LBe 16O (K-, p- g) 16LO 26.1±2.0 keV 43±5 keV Eg(keV) Eg(keV) MeV MeV PRL 88 (2002) 082501 PRL 93 (2004) 232501 consistent with Meson Exch. Model consistent with Quark Cluster Model

  15. eh 2mqc mB looks OK withmq= ~100% Doppler Shift Attenuation Method : mq: constituent quark mass gc mq reduction by chiral sym. rest. -> mB enhances ?? in s-orbit -0.4 gL(free) = -1.226 mN g factor of L in nucleus mL in nucleus -> medium effect of baryons Can be investigated using a L in 0s orbit • Direct measurement of mLin nucleus extremely difficult (t~ 0.1-- 0.2 ns) • B(M1) of L-spin-flip M1 transition -> gL Prelim. data for 7LLi(3/2+->1/2+)(E930, M.Ukai)gL = -1.1 +0.6mN Applied to “hypernuclear shrinkage” in 7LLi from B(E2) : PRL 86 (’01)1982 => J-PARC E13: ~ 5% accuracy for B(M1)

  16. 2.3 (e,e’K+) spectroscopy

  17. Characteristic features of (e,e’K+) experiments at JLab Sub MeV resolution  High quality primary e beam Proton to L  Neutron rich L hypernuclei Mirror to those by (p+,K+) Large angular momentum transfer  Stretched states (similar to (p+,K+)) Spin-flip amplitude  Unnatural parity states Calibration by p(e,eK+) S, L -> Absolute mass scale -> Fine structure of bound and unbound states -> Accurate BL values

  18. Improvement of Resolution 12C(p+,K+)12LC @ KEK-PS DE = 2 MeV (FWHM) PRC 64 (2001) 044302 12C(e,e’K+)12LB @ JLab Hall A DE ~ 0.65 MeV (FWHM) PRL 99 (2007) 052501 preliminary 12C(e,e’K+)12LB @ JLab Hall C DE ~ 0.5 MeV (FWHM)

  19. To beamdump HKS ENGE Splitter Recently replaced to new spectrometers Target Electronbeam Dedicated spectrometer at Hall C Dp/p = 4×10-4 (FWHM) e’ 0.3 GeV/c e 1.8 GeV Took data for 7LHe, 9LLi, 10LBe, 12LB , 32LAl, 52LV

  20. A new test of charge symmetry breaking Hall C #1 #1 9 events => Ln≠Lp very large CSB? Tests by non-emulsion methods awaited 7Li(e,e’K+)7LHe ?? 7Li(e,e’K+)7LHe (K-,p- ) prelim. -5.68±0.03±0.22 Absolute mass scale well calibrated via H(e,e’K+)L,S0 T=1 calc. by Hiyama Juric et al. NP B52 (1973) 1 g ray Tamura et al. PRL 84 (2000) 5963 T=0

  21. 3. S-nuclear systems

  22. The only S-nuclear bound state so far observed No S bound states peaks in other S hypernuclei Substitutional (DL=0) state: n(s1/2)-1L(s1/21) T=1/2, 3/2 S=0 4SHe T=3/2 only S=0 Large spin-isospin dependence (I,S) = (3/2,0), (1/2,1) attractive (3/2,1), (1/2,0) repulsive -- Consistent with meson exchange models How about spin-isospin averaged potential? S in neutron stars? BNL-AGS, Nagae et al., PRL 80 (1995) 1605

  23. Strong repulsion coming from • Pauli effect between quarks? • Quark Cluster Model • Lattice QCD SN (I,S) = (3/2,1) High statistics S+p/ S-p scattering experiment planned at J-PARC S--28Si Nuclear potential (KEK E438) 28Si (p-,K+) at 1.2GeV/ with SKS V0 ~ -10 MeV W0 ~ -10 MeV • S’s never appear in n-stars? Noumi et al., PRL 87(2002) 072301 Strongly repulsive potential (U~ +30 MeV) How repulsive are (I,S) = (3/2,1), (1/2,0) channels?

  24. 4. Double strange nuclear systems

  25. Nakazawa (Hyp-X conf.) 11 Be 6 He 6 He (unique and accurate) 10 Be* (w/ theoretical help) LL LL LL LL #8 LL hypernuclei via emulsion+counter hybrid method(KEK E373) Nagara event DBLL= 3.82 ±1.72 MeV Mikage event DBLL= 0.67±0.17 MeV Hida event Demachi-yanagi event DBLL= -1.52 ±0.15 + 3.0 cf. Ex = 3.0 DBLL= 2.27 ±1.23 MeV

  26. p L n DBLL= 0.67±0.17 MeV LL interaction strength Nagara event Well-identified double L hypernucleus event produced from K- p -> X K+ reaction Mass -> Interaction betweenLL is weekly attractive Bound H dibaryon does not exist. Takahashi et al., PRL 87 (2001) 212502 Takahashi et al., PRL 87 (2001) 212502 => ~10 times more LL hypernuclear events X hypernuclear spectroscopy, X atomic X-rays at J-PARC

  27. 5. Weak decays of L hypernuclei(New FINUDA data)

  28. S.Bufalino, Monday Mesonic weak decays (FINUDA) Agnello PLB 681 (2009) 139 15O: 1/2-gs & sd(~6 MeV) p- energy spectra and decay rates were measured for present data L->pp- decay in nuclei spin-parity assignment pion optical potential L wavefunciton in nucleus T. Motoba PTPS 117 (1994) 477 previous data A.Gal NPA 828 (2009) 72 S.Bufalino - HADRON2011, June 13-17 München T. MotobaNPA 489 (1988) 683. A Jp (15LNg.s.) = 3/2+ strong nuclear structure effects A

  29. S.Bufalino, Monday 15 MeV Non Mesonic Weak Decay (FINUDA) Spectra contain LN->NN, FSI, and LNN->NNN (2N-induced nonmesonic decay) NPA 804 (2008),151 NPA 804 (2008),151 NPA 804 (2008),151 G2 G2/Gp = 0.24 ± 0.10 = GNM Gn/Gp+ 1 + G2/Gp K-np background subtracted M. Kim et al., PRL 103 (2009) 182502: 0.29 ± 0.13 12LC M.Agnello et al., PLB 685 (2010) 247

  30. 6. Summary • (p-,K+) spectroscopy for L hypernuclei Neutron-rich10LLi observed. Will be used to investigate LNN force. • g-spectroscopy of L hypernuclei: Almost all p-shell data accumulated and spin-dependent LN interactions well determined. gL to be measured from B(M1). • (e,e’K+) spectroscopy of L hypernuclei at JLab: Resolution improved to ~ 0.5 MeV (FWHM). New test of LN charge symmetry breaking. • S-nuclear systems: strong repulsive potential observed. • 6LLHe event revealed LL force weakly attractive. • Mesonic and nonmesonic weak decay (LNN->NNN) data from FINUDA. • Further progress in strangeness nuclear physics is expected at J-PARC, JLab, DAFNE, GSI, FAIR.

  31. J-PARC will answer Summary for the YN, YY interactions Established SuggestedUnknown • LN Attractive (~ 2/3 of NN force) <- LZ L-single particle orbit data Very small LS force, small spin-spin/ tensor forces <- LZ p-shell g-ray data etc. LN-SN coupling force <- s-shell L hypernuclei p-wave force?Charge symmetry breaking (Lp≠Ln)? • SN Strong isospin dependence (attractive for T=3/2,S=0 and T=1/2,S=1) <- 4SHe Strongly repulsive in average<- 28Si (p-,K+) spectrum How large is the repulsive (T=3/2,S=1) channel? • LL Weakly attractive <- 6LLHe LL-XN-SS coupling force ? • XN Weakly attractive?<- 12C (K-,K+) spectrum Isospin dependence? • LS, SS, XL, XS, XX; WN Unknown at all ??

  32. Thank you for your warmhearted supports and encouragement to Japan, particularly to Tohoku University (Sendai) and J-PARC/KEK. We are recovering everything back and going forward.

  33. PRC 64 (2001) 044302 g-ray data BNL E930 J-PARC will answer -> UL = - 30 MeV KEK E373 : Nagara event Summary for the YN, YY interactions Established SuggestedUnknown • LN Attractive (~ 2/3 of NN force) <- LZ L-single particle orbit data Very small LS force, small spin-spin/ tensor forces <- LZ p-shell g-ray data etc. LN-SN coupling force <- s-shell L hypernuclei p-wave force?Charge symmetry breaking (Lp≠Ln)?? • SN Strong isospin dependence (attractive for T=3/2,S=0 and T=1/2,S=1) <- 4SHe Strongly repulsive in average<- 28Si (p-,K+) spectrum How large is the repulsive (T=3/2,S=1) channel? • LL Weakly attractive <- 6LLHe LL-XN-SS coupling force ??? • XN Weakly attractive??<- 12C (K-,K+) spectrum Isospin dependence??? • LS, SS, XL, XS, XX; WN Unknown at all ???

  34. J-PARC E10 6LH “hyperheavy hydrogen” 9LHe deeply bound by additional binding (+1.4 MeV) from LNN force (Akaishi) single charge exchange (e,e’K+) (K-,p-) (p+ ,K+) double charge exchange (p- ,K+) p- p p -> L n K+ 2-step charge exchange (p-p->p0n, p0p->K+L etc.) Via S- admixture in L hypernuclei (p- p->S- K+, S- p<->Ln) How to extend S=-1 nuclear chart? target nuclei

  35. Motivation • Baryon-baryon interactions Unified understanding of “extended nuclear force” Understanding of short range parts of nuclear force Test of lattice QCD  High density nuclear matter in neutron stars • Nuclear medium effects using hyperons gL in nucleus • Impurity effect to nuclear structure Shrinkage, Change of deformation, Dissaperance of halo and cluster structure,…

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