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

2. Contents 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)

3. 1. Introduction

4. World of matter made of u, d, s quarksN Z
L, S Hypernuclei
LL, X Hypernuclei
Nu ~ Nd ~ Ns
Strangeness in neutron stars ( r > r0 )
Strange hadronic matter (A → ∞)
“Stable”
Strangeness -1 -2
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. 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
One probable assumption
but should be determined
by experimets.
We still need
XN, LL, SN, KN forces, LN p-wave force, NNN and YNN force, … - r0
n star
Vela Supernova remnant
Nu ~ Nd ~ Ns
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. L hypernuclear 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+) spectroscopy incl. 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
for LN spin-dependent forces, LN-SN force, ..
Mass of hypernucleus -BL (MeV)
(p,K+) -> (e,e’K+) at JLab
g spectroscopy at KEK/BNL, J-PARC
Hotchi et al., PRC 64 (2001)

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

10. Neutron-rich hypernuclei
p- p p -> L n K+
2-step charge exchange
(p-p->p0n, p0p->K+L etc.)
Via S- admixture in L hyp.
(p- p->S- K+, S- p<->Ln)
10B (p-, K+) 10LLi
pp~1.2 GeV/c
11.1±1.9 nb/sr
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 ?
Akaishi et al.,
PRL 84 (2000) 3539
Almost no
background
KEK E521, K6+SKS
Saha et al., PRL 94 (2005)
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. Hypernuclear g-ray data
Hyperball 1998~ 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. LN spin-dependent interactions
Low-lying levels of L hypernuclei
Level spacing:
Linear combination
of D, SL, SN, T
Millener’s approach
Two-body LN effective interaction - V D SL SN T
p-shell: 5 radial integrals for sL pN w.f. s
D =∫V (r) |u (r)|2 r2dr, r = r - r sL pN
Well known
from UL = - 30 MeV
g-ray data => D = 0.33 (0.43 for A=7), SL = -0.01, SN = -0.4, T= [MeV]
Small spin-dependent forces have been established.

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

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

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

19. Dedicated spectrometer at Hall C
ENGE
HKS
Splitter
Electron beam
To beam dump
Target
Dp/p = 4×10-4 (FWHM)
Recently replaced
to new spectrometers
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
(K-,p- )
=> Ln≠Lp very large CSB?
Tests by non-emulsion methods awaited #1
9 events ??
Juric et al.
NP B52 (1973) 1
g ray
calc. by Hiyama
Tamura et al.
PRL 84 (2000) 5963
T=0
T=1
7Li(e,e’K+)7LHe
Hall C
Absolute mass scale
well calibrated via H(e,e’K+)L,S0
prelim.
-5.68±0.03±0.22
7Li(e,e’K+)7LHe

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. S--28Si Nuclear potential (KEK E438)
28Si (p-,K+) at 1.2GeV/ with SKS
Strong repulsion coming from
Pauli effect between quarks?
Quark Cluster Model
Lattice QCD
SN (I,S) = (3/2,1)
V0 ~ -10 MeV
W0 ~ -10 MeV
S’s never appear in n-stars?
High statistics
S+p/ S-p scattering experiment
planned at J-PARC
Noumi et al., PRL 87(2002)
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. LL hypernuclei via emulsion+counter hybrid method (KEK E373)
Nakazawa (Hyp-X conf.)
Nagara event
Mikage event
DBLL= 3.82 ±1.72 MeV #8
6 He
(unique and
accurate) LL
6 He LL
DBLL= 0.67±0.17
MeV
11 Be LL
Hida event
Demachi-yanagi event
10 Be*
(w/ theoretical
help) LL
DBLL=
-1.52 ±0.15
+ 3.0
cf. Ex = 3.0
DBLL= 2.27 ±1.23 MeV

26. LL interaction strength
Nagara event
Well-identified
double L hypernucleus event L n p
produced from
K- p -> X K+ reaction
Mass ->
DBLL = 0.67±0.17 MeV
Interaction between LL is weekly attractive
Bound H dibaryon does not exist.
Takahashi et al., PRL 87 (2001)
Takahashi et al., PRL 87 (2001)
=> ~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 - HADRON2011, June 13-17 München
S.Bufalino, Monday
Mesonic weak decays (FINUDA)
p- energy spectra and decay rates were measured for
15O: 1/2-gs & sd (~6 MeV)
Agnello PLB 681 (2009) 139
L->pp- decay in nuclei
spin-parity assignment
pion optical potential
L wavefunciton in nucleus
present data
T. Motoba PTPS 117 (1994) 477
previous data
A.Gal NPA 828 (2009) 72 A
S.Bufalino - HADRON2011, June München
T. Motoba NPA 489 (1988) 683.
Jp (15LNg.s.) = 3/2+
strong nuclear structure effects A

29. Non Mesonic Weak Decay (FINUDA)
S.Bufalino, Monday
Non Mesonic Weak Decay (FINUDA)
Spectra contain LN->NN, FSI, and
　　　　LNN->NNN (2N-induced nonmesonic decay)
15 MeV
NPA 804 (2008),151
NPA 804 (2008),151
NPA 804 (2008),151
K-np background subtracted
GNM G2 =
Gn/Gp+ 1 + G2/Gp
G2/Gp
= 0.24 ± 0.10
M. Kim et al., PRL 103 (2009) :
　 ± LC
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. Summary for the YN, YY interactions
Established Suggested Unknown 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 ??
J-PARC
will answer

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.

34. Summary for the YN, YY interactions
PRC 64 (2001)
-> UL = - 30 MeV
Summary for the YN, YY interactions
Established Suggested Unknown
KEK E373 : Nagara event 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 ???
J-PARC
will answer
g-ray data
BNL E930

35. How to extend S=-1 nuclear chart?
6LH “hyperheavy hydrogen”
9LHe
J-PARC E10
deeply bound by additional
binding (+1.4 MeV)
from LNN force (Akaishi)
target nuclei
(e,e’K+)
single charge exchange
(p+ ,K+)
(K-, p-)
(p- ,K+)
double charge exchange
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)

36. 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,…