Strangeness Nuclear Physics
• Nuclei: many body systems of nucleons
– Can be extended by adding
other flavors: strangeness, charm, ...
Unexplored “space”
S=0 “surface”
Physics interests
• New interaction
– Extended nuclear force to flavor SU(3) world
– Unified understanding of Baryon-Baryon force –
What is its origin?
– Is traditional meson exchange model enough?
Need quark/gluon picture?
• Property of hyperons in nuclei?
– Hyperons can mix easily (e.g., LN-SN, LL-XN)
→ Dynamical systems can be made
– Effective mass, magnetic moment, ...?
• What happens to nuclei? Impurity effect?
– Collective motion? High density matter?
Relation with neutron star
• Naively, hyperons are expected to appear in NS
– E.g., Fermi gas model w/o interaction
Fermi energy of n: 𝐸𝐹 = 𝑝𝐹 2 /2m~58(𝜌/𝜌0 )2/3 MeV
𝐸𝐹 > 𝑚Λ − 𝑚𝑛 at 𝜌~5𝜌0
– L, S-, X- may be important
• Of course, details depend on
nuclear interaction
– Most of present calculations
expect hyperons at 2~3𝜌0
– Can be studied by SNP at J-PARC
– Especially, X potential in nuclei
is a key
• Mass, size, ...?
Nuclear & Hadron Physics in J-PARC
Experiments
at aPhysics
glanceat(not
all)
Nuclear
& Hadron
J-PARC
d
High Density Nuclear Matter, Nucelar Force
u
Strange
ness
Hypernuclei
6
LLHe
K0 → p0 nn
L
s
d u
Pentaquark +
Origin of Mass
Confinement
LL, X Hypernuclei
Z
-1
0
Quark
L, S Hypernuclei
-2
N
L,X
SKS
Free quarks
K1.8
Bound quarks
Why are bound quarks heavier？
Mass without Mass Puzzle
K1.8BR
KL
K1.1
K-meson
Implantation of
High Density
Kaon and the
nuclear shrinkage Nuclear Matter,
Nucelar Force
COMET
Beam line
Ｋ−
T-Viola
tion
Ｘray
Kaonic atom
Kaonic nucleus
nucleus
m-e conversion

μ−
e-
Part I.
(selected) Results from
recent experiments
E27, E15, & E13
Deeply bound Kaonic nuclei
L(1405) = K-p bound state  deeply bound nuclei?
Kaon condensation in neutron stars?
DISTO
(PRL 94, 212303)
FINUDA
PRL104, 132502
Akaishi & Yamazaki, PRC 65 (2002) 044005
 No observation in HADES, LEPS, …
BK > 100 MeV??
E27
• Search for K-pp by d(p,K+) reaction
– missing mass spectroscopy
Decay counter to detect ppp
from Kpp  Lp  ppp
d(π+, K+) at 1.69 GeV/c (Inclusive spectrum)
Y* peak; data = 2400.6 ± 0.5(stat.) ± 0.6(syst.) MeV/c2
+2.8
sim = 2433.0 -1.6 (syst.) MeV/c2
+2.9
``shift” = －32.4 ± 0.5(stat.) -1.7 (syst.) MeV/c2
Mass shift of L*(1405) and/or S*(1385)?
due to final state interaction?
Gaussian fit
PTEP 101D03 (2014)
10
Range counter array(RCA)
for the coincidence measurement
• RCA is installed to measure the proton from the K-pp.
– K-pp→Λp→pπ-p; K-pp→Σ0p→pπ-γp; K-pp→Ypπ→pπp+(etc.)
• Proton
is also the
produced
from the QF
processes.
We suppress
QF background
by tagging
a proton.
+Λπ0, Λ→pπ–☆
π+``n’’→K
Seg2 and
5 are free from QF background.
More strongly
suppress
by tagging
two protons.
• However,
these
proton’s
kinematics
is different.
K+
p
p
π+
11
``K-pp’’-like structure(coincidence)
• Broad enhancement ~2.28 GeV/c2 has been observed in
the Σ0p spectrum.
PTEP 021D01 (2015)
• Mass:
• Width:
• dσ/dΩ``K‐pp’’→Σ p =
(BE:
)
0
T. Sekihara, D. Jido and Y. Kanada-En’yo, PRC 79, 062201(R) (2009).
•
[Theoretical value: ~1.2]
<2proton coincidence analysis>
π+d→K+X, X→Σ0p
<1 proton coincidence probability>
12
Discussion on the
``K pp’’-like
structure
• Obtained mass (BE ~ 100 MeV) and broad width are
not inconsistent with the FINUDA and DISTO values.
– Theoretical calculation for the K-pp is difficult to
reproduce such a deep binding energy about 100 MeV.
– Other possibilities?
• A dibaryon as πΛN – πΣN bound states? H. Garcilazo and A. Gal, NPA 897, 167 (2013).
(It should not decay to the Λp mode because of I = 3/2.)
T. Uchino et al., NPA 868, 53 (2011).
• Λ*N bound state?
A. Dote, T. Inoue and T. Myo, PTEP 2015 4, 043D02 (2015).
• A lower πΣN pole of the K-pp?
(The K-pp might have the double pole structure like Λ(1405).)
―
• Partial restoration of chiral symmetry on the KN interaction?
S. Maeda, Y. Akaishi and T. Yamazaki, Proc. Jpn. B 89, 418 (2013).
13
E15
E15 result
PTEP 2015, 061D01
• No peak below
Kpp threshold
E27 result
• Not a kaonic
bound state,
but NSp
resonance??
E13 g-ray spectroscopy of hypernuclei
•
4 He:
L
Charge symmetry
breaking in LN interaction?
compare the mirror nuclei:
4 He and 4 H
L
L
• 19LF: First g-ray measurement
on sd-shell hypernuclei
– How effective interaction
changes compared to
p-shell hypernuclei?
• Hyperball-J
– 28 germanium detectors
+ PWO Compton suppressor
dedicated for hypernuclei
arXiv:1508.00376
E13 result (1) – 4LH
1+
1/2+
3He
0+
4
LHe
• Eg=1406±2±2 keV
• Corresponding energy in
4 H: 1090±20 keV
L
 Indication of large
charge symmetry breaking
•
LN-SN coupling effect
with S mass difference?
E13 result (2) – 19LF
Doppler shift not corrected
𝟏𝟗
selected
unbound
𝐅
𝟏𝟗
𝚲𝐅
𝐞+ 𝐞− annhilation
Selected
𝟏𝟗
𝚲𝐅
𝟏𝟗
𝚲𝐅
𝟏𝟗
𝚲𝐅
g.s.
Unbound
𝟏𝟎
𝐁
Analysis
in progress
Part II.
Coming experiments
E03 & E07
E03 experiment
• World first measurement of X rays from X-atom
– Gives direct information on the XA optical potential
• Produce X- by the Fe(K-,K+) reaction, make it stop in the
target, and measure X rays.
• Aiming at establishing the experimental method
X-
Fe target
(dss)
K-
K+
X-
Fe
X ray
X ray
Energy (arbitrary scale)
X atom level scheme
...
l=n-3
l=n-1 (circular state)
l=n-2
...
Z
nuclear absorption
...
...
X
Z
l (orbital angular momentum)
X ray energy shift – real part
Width, yield – imaginary part
Successfully used for p-, K-,`p, and S-
X
paration of KURAMA spectrometer system
Detectors are ready for installation
6 / 13
st all detectors are
cated and being tested.
TOF
L
oster
: 303 H. Ekawa
Hyperball-J
CH
CH (Charge Hodoscope)
SSD
K+
X-
K-
am Hodoscope)
K+
Tagging
‘p’(K-,K+
)X -
KURAMA
(1.66 GeV/c)
TOF
DC3
DC3
BAC
K-
PVAC (Proton Veto AC)
X-
DC2
BAC
FBH
BH2
KURAMA
PVAC
FAC
DC1
DC2
E07 LL Hypernuclei
Hybrid emulsion method
Goal:
• 10000 stopped
X- on emulsion
• 100 or more
double-L HN
events
• 10 nuclides
Chart of
double-L
hypernuclei
Production of LL-nuclei
by fragmentation
Xp  LL stay in the
nucleus （~10％）
Systematics of LL binding energy
•
LL binding energy may be different for each nucleus
– For example by hyperon mixing effect
5
LLHe
6
LLHe
p
n
L
p
n
L
p
n
X
p
n
X
Suppressed
Enhanced
E03/07 run plan in 2015-2017
• Test beam for 3 days in October 2015
– Confirm detector performance
– Measurement of beam profile
• Installation of KURAMA spectrometer from January
– Commissioning beam time in Spring.
• E07 beam time in 2016 with full statistics
• E03 beam time is expected after E07.
– Likely in early 2017.
– We will have more than 1x1011 K- on target
(10% of proposal)
– Observation of X-atomic X ray should be possible,
though finite shift/width may not be observable.
Even further...
Extended
Hadron Hall
Details
under discussion
Summary
• Search for deeply bound Kaonic nuclei (E27, E15)
– Mass shift of L*(1405) and/or S*(1385)?
– Hint of deeply bound “Kpp”-like structure observed in d(p+,K+)
reaction, but not observed in (K-,n) reaction
– Kaonic nuclei?, SpN?, OR, something else?
• E13: g-ray spectroscopy of hypernuclei
– g-ray from 4LHe observed
 large charge symmetry breaking
– Several g rays are seen from 19LF (analysis in progress)
• Coming experiments – on doubly strange systems
– E03: X-ray spectroscopy of X atom
– E07: Systematic study of double-L hypernuclei in emulsion
– Expect to run in 2016 & 2017
BACK UPS
Calibration: p(π+, K+)Σ+ at 1.69 GeV/c
Σ+
Σ(1385)+
Data:
M = 1381.1 ± 3.6 MeV/c2
Γ = 42 ± 13 MeV
PDG: M = 1382.8 ± 0.35 MeV/c2,
Γ = 36.1 ± 0.7 MeV
32
θπK dependence
(＋data, ―sim)
Y* peak positions are
shifted to the low
mass side for all
scattering angles.
< Peak position >
＋ data
＋ simulation
33
HADES experiment for Λ(1405)
The peak position of Λ(1405)
is shifted to low-mass side.
M = 1385 MeV/c2,
Γ = 50 MeV
S-wave Breit Wigner function
34
E19 Experiment
Search for pentaquark, +
• There are two kinds of usual hadrons (= feel strong force)
– Baryon (Fermion):
Meson (Boson):
– Color neutrality required from QCD
But they are not the only cases
 Exotic hadrons
– Pentaquark = 5 quarks
Pentaquark +
• First reported in
2003 by LEPS
collaboration
• Both positive and
negative results
– Still controversial
• Mysteries
– Why so narrow?
G < 1 MeV
– Spin-parity?
– What’s that
eventually?
T. Nakano et al.,PRC79 (2009) 025210
High resolution search by p(p-,K-)
• A good resolution:
~2 MeV (FWHM)
– thanks to SKS
• Why high resolution?
– Good S/N ratio
– Width measurement
Almost certainly G < 1 MeV
• Typical resolution
in the past ~ 10 MeV
– No high resolution search
– There is a good chance
Moritsu et al., PRC90 (2014) 035205
• Spectra well represented by known backgrounds
at both energies
Upper limit on decay width
• Based on an effective
Lagrangian approach:
Hyodo et al.,
PTP128 (2012) 523
• Upper limit:
0.36 MeV for ½+
1.9 MeV for ½For most conservative cases,
taking theoretical
uncertainties into account
• Comparable to DIANA result
E10
Neutron rich hypernuclei via (p-,K+) reaction
L-hypernuclei
N~Z (I=0 or 1/2)
Non Charge-Exchange (NCX)
( K - , p - ) (p + , K + )
hyperfragments
by emulsions exp.
ordinary nuclei
N>>Z
(I=3/2 or 2)
( K - , p + ) (p - , K + )
Double Charge-Exchange (DCX)
J-PARC E10
41
ΛN-ΣN Mixing in Λ Hypernuclei
• Smaller mass difference
~300 MeV in DN vs ~80 MeV
• Suppressed in I=0 core
– Stronger mixing expected
for neutron rich hypernuclei
if core isospin=0
A(I=0)
L
A(I=0)
S
if core isospin0
A(I0)
A(I0)
OK!
L
S
Result
PLB 729 (2014) 39
• No peak
observed
• ds/dW
< 1.2 nb/sr
– 10 times
smaller than
10 Li
L
– Does it really
bind?