加速器を用いた
ハドロン物理実験
K. Ozawa (KEK)
内容
• 原子核の性質
– ストレンジネスで探る原子核内部
– ハドロンーハドロン相互作用
– 原子核媒質とメソン
• 核子（バリオン）の中身
– ストレンジバリオン
– Di-quark 相関
2013/10/30
Hadron Experiment, K. Ozawa
2
J-PARC
Tokai, Japan
(Japan Proton Accelerator Research Complex)
Material and Biological
Science Facility
400 MeV Linac
(350m)
3 GeV Synchrotron
(333 mA)
Neutrino Facility
50 (30) GeV
Synchrotron (15 mA)
Hadron Hall
60m x 56m
World-highest beam intensity : ~1 MW
x10 of BNL-AGS, x100 of KEK-PS
2013/10/30
Hadron Experiment, K. Ozawa
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Nuclear & Hadron Physics at J-PARC
d
Strangen
ess
Hypernuclei
u
LL, X Hypernuclei
Z
Pentaquark +
L, S Hypernuclei
-2
-1
0
6
LLHe
s
d u
N
L,X
SKS
K1.8BR
K1.8
KL
K1.1
K meson
Implantation of
Kaon and the
nuclear shrinkage
Quark
Ｋ−
Free quarks
Ｘray
2013/10/30
Kaonic atom
Hadron Experiment, K. Ozawa
Kaonic nucleus
Bound
quarks
Why are bound quarks haevier？
4
Mass without Mass Puzzle
South side
North side
KL
SKS
K1.8BR
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Hadron Experiment, K. Ozawa
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SKS Spectrometer
Q13
Q12
D4
2013/10/30
Q10
Q11
Hadron Experiment, K. Ozawa
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核構造とストレンジネス
2013/10/30
Hadron Experiment, K. Ozawa
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原子核構造
調和振動子
井戸型
偶－偶核の第一励起準位エネルギー
（閉殻構造、魔法数の存在）
ウッド・サクソン
2013/10/30
励起準位（調和振動子、井戸型）
Hadron Experiment, K. Ozawa
1体ポテンシャルによる励起準位
8
ストレンジネス
ストレンジネスは、Pauli Blockingを受けな
いので、原子核の中に置ける。
実際に、殻構造があることを実証
PRC 64 (2001) 044302
-> UL = - 28 MeV
(c.f. UN = -50 MeV)
束縛エネルギーは、違っていた。
2013/10/30
Hadron Experiment, K. Ozawa
1体ポテンシャルによる励起準位
9
ストレンジネス束縛エネルギー
束縛エネルギーの違いがもたらす物理
One example…
Baryon fraction in neutron star
PRC 64 (2001) 044302
-> UL = - 28 MeV
(c.f. UN = -50 MeV)
Experimental
input to models
Schaffner-Bielich, NP A804 (2008).
More experimental information on LN, XN, LL, SN interactions are awaited.
2013/10/30
Hadron Experiment, K. Ozawa
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Precise measurements of LN (E13)
• g spectroscopy for light hyper nuclear using
(K-, p-) reaction at pK=1.5 (or 1.1) GeV/c.
• Physics: LN interaction
– Charge symmetry breaking in LN interaction
•
4
•
19
•
10
LHe
: Large CSB is suggested
– sd-shell hypernuclei for A-dependence of LN
interaction
LF
: The first sd-shell hypernuclei
LB
and 11LB
– Confirm LN spin-dependent forces and study
LN-SN coupling force
Beam
• Physics: g-factor of L in nucleus
– Spin-flip B(M1) measurement for gL in a
nucleus
•
7
LLi
: Least ambiguities and most reliable.
• Hyper Ball-J is almost ready and we will take
the first experimental data soon.
2013/10/30
Hadron Experiment, K. Ozawa
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LL interaction (E07)
• At KEK-PS E373, there are ~ 700 X stops and one
NAGARA event is observed.
– ΔBLL = 1.01±0.20 MeV for L6LHe
• At J-PARC, S=-2 nuclear chart is studied by ~102 LLZ via
104 X --stopping events.
– DBLL of several nuclides will provide definitive information
on LL interaction and structure of S=-2 nuclei.
Experimental Method
(Nuclear Emulsion)
The experiment is under
preparations and it will
be performed in the end
of this year or early next
year.
2013/10/30
Hadron Experiment, K. Ozawa
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XN interaction (E05)
• Discovery of X-hyper nucleus
using 12C(K-,K+) reaction
–
Expected Spectrum
(Will be improved using a new spectrometer)
12 Be
X
• Missing mass spectroscopy
– High resolution
• Originally, 3 MeV(FWHM)
• 1.5 MeV will be achieved
using a new spectrometer
• Experiment will start in 2015
and we can expect more than
200 events of X-hyper
nucleus
– Precise spectroscopy
2013/10/30
Hadron Experiment, K. Ozawa
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ハドロンーハドロン相互作用
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Hadron Experiment, K. Ozawa
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バリオンーバリオン相互作用
ストレンジネスを含む相互作用の違いの起源はどこに？
中性子・陽子の相互作用の研究は、
散乱実験
これはストレンジネスでも可能
２体束縛状態（重陽子）の研究
ストレンジネスセクターに存在しない。
図は、八木浩輔・原子核物理学
Example： 陽子・中性子・重陽子の性質
中性子・陽子散乱の角分布
2013/10/30
Hadron Experiment, K. Ozawa
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SN Scattering (E40)
• Differential cross section of S-p and S+p scattering with 100
times larger statistics
• Motivation: See “quark-Pauli effect” Hyperon production
S+p
1.3 GeV/c p+- p -> K+ S+- reaction
S+- track not directly measured
Measure proton momentum vector
-> kinematically complete
(quark Pauli)
quark + meson exch
meson exch
Evaluation of quark Pauli
effect and understanding
the origin of the hard core
of the nuclear force
2013/10/30
Hadron Experiment, K. Ozawa
New experimental
techniques with MPPC and
Fiber Tracker will be used
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メソン－バリオン相互作用（KN, E15）
Physics motivation
Experimental scheme
Experimental setup
2013/2/11
J-PARC Future 2013, K. Ozawa
Experiment is on-going
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Results of an engineering run
XY plane
YZ plane
Liquid 4He inside
Target-image together with material around
has been reconstructed by the CDS
L
2013/10/30
pp- invariant-mass
spectra reconstructed
by the CDS
Charged particles from the target have
been successfully identified by the CDS
 CDS and Liquid Helium
target system successfully
worked
 Ready to explore kaonicnuclei @ K1.8BR
 Data Taking in this May!
Hadron Experiment, K. Ozawa
~10,000 Ls have been accumulated
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E27: Search for “K-pp” bound state in the d(p+,K+)X reaction
• “K-pp” is produced through L* doorway in the d(p+,K+) reaction
d
π+
n
p
Λ*
K+
K-pp
• Semi-exclusive measurement by Range
Counter Array (RCA) in order
to suppress quasi-free B.G.
Data already collected and
results will be reported soon.
2013/10/30
Hadron Experiment, K. Ozawa
p
counts (/3M beam・10days )
– K-pp  L p1, L  p2 p– K-pp S0 p1, S0  (Lg)  p2 p- g
– p+d  L* K+ p1s, L*  S p, S+  p2 p0
K+
RCA
Momproton>350MeV/c
Expected point by
FINUDA, DISTO
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Missing mass d(π+,K+) [GeV/c2]
原子核媒質とメソン
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Hadron Experiment, K. Ozawa
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媒質からの励起状態としてのハドロン
Mass [GeV]
• カイラル対称性の自発的
破れに伴う質量の獲得
構成子クォーク
の質量を獲得
NGボソンとしての
擬スカラー中間子
（Jp=0-）
• π中間子が異常に軽い（Mp
~ 130 MeV/c2 ）ことは、対
称性の自発的破れに伴う
南部ゴールドストンボソン
と理解
• 実際にカイラル対称性は
破れている。
– カイラルパートナーに質
量差があることが知られ
ている
媒質中での中間子の測定
原子核媒質の性質の測定
原子核-中間子相互作用の測定
2013/10/30
Hadron Experiment, K. Ozawa
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p 束縛状態
Large overlap of wave function
Sensitive to p-nucleus
strong interaction potential
Measure binding energy can
be converted to this b1
information
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Hadron Experiment, K. Ozawa
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Exp. Results
K. Suzuki et al., Phys. Rev. Let., 92(2004) 072302
p bound state is observed in
Sn(d, 3He) pion transfer reaction at GSI.
Reduction of the chiral order parameter,
f*p(r)2/fp2=0.64 at the normal
nuclear density (r = r0 ) is indicated.
Experiment is
continued at RIKEN
and positive results
are already
obtained.
2013/10/30
Hadron Experiment, K. Ozawa
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Other Pseudo Scalar Meson: h
LOI by K. Itahashi et. al
Calc. by H. Nagahiro, D. Jido,
S. Hirenzaki et. al
Forward neutron is detected.
missing mass distribution is measured.
Simulation
In addition, measurements of invariant
mass of N* decay
2013/10/30
Hadron Experiment, K. Ozawa
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Other Pseudo Scalar Meson: h’ @ GSI
Reaction is similar with pionic
atom experiment.
Theoretical calculation by H. Nagahiro
2013/10/30
Hadron Experiment, K. Ozawa
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反クォーク・クォーク凝縮量
• 反クォーク・クォーク凝縮量と関係した測定量
– ベクトル中間子や軸性ベクトル中間子の質量分布
– Weinberg type sum rule
Hatsuda, Koike and Lee, Nucl. Phys. B394 (1993) 221
Kapusta and Shuryak, Phys. Rev. D49 (1994) 4694
– たとえば、自由空間中で、t粒子の崩壊からの分布の測
定がある。（ALEPH, Phys. Rep. 421(2005) 191）
– 自由空間以外での測定は、実験的に難しい
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Hadron Experiment, K. Ozawa
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Example: sum rule
e.g. Weinberg type QCD
sum rule
Hatsuda, Koike and Lee, Nucl. Phys. B394 (1993) 221
Kapusta and Shuryak, Phys. Rev. D49 (1994) 4694
ALEPH, Phys. Rep. 421(2005) 191
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Hadron Experiment, K. Ozawa
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さらに、反クォーク・クォーク凝縮量
• QCD sum ruleをベクトル中間子の質量分布に適
用し、凝縮量と関係づけられると示唆
Hatsuda and Lee, Phys. Rev. C46 (1992) R34
• 実験的には、
– ベクトル中間子質量分布の測定は可能
– 原子核中や高温ハドロン物質中での測定も可能
• 内包する凝縮量の違いを反映する
• 質量獲得モデルや“QCD媒質”状態予想の検証
– 自由空間以外でのベクトル中間子の質量分布測定
が基礎情報として重要
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Hadron Experiment, K. Ozawa
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KEK-PS E325実験へ
• 原子核密度に対する面白い予想の存在
– 凝縮量と質量分布の関係と以下の仮定を基に予想
• 質量分布の形
Hatsuda and Lee, Phys. Rev. C46 (1992) R34
– 凝縮量の変化の効果をポール位置の変化に集約
• 核子内の凝縮量の評価
• 凝縮量は、密度に線形に変化
Hatsuda and Kunihiro, Nucl. Phys. B387 (1992) 715
– 原子核中で、18％（ρ, ω）と1.8%（φ）の質量変化を予測
• 実験的に検証可能
– 原子核中での崩壊により質量分布を測定
– 終状態相互作用を避けるために電子対崩壊を選択
– バックグランドやρ-ω干渉に関する不定性を避けるため、φ中間
子に対して測定
• φ中間子の幅は狭い（ 4.3 MeV/c2 ）。質量変化が測定しやすい。
• あらわなハドロン相互作用の効果は小さい。
– e.g. Binding energy of fN is 1.8 MeV (Phys. Rev. C 63(2001) 022201R)
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Hadron Experiment, K. Ozawa
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KEK-PS E325実験の概要
12 GeV proton induced.
p+A  f + X
Electrons from fdecays are detected.
Target
Carbon, Cupper
0.5% rad length
KEK E325
2013/10/30
Hadron Experiment, K. Ozawa
30
Clear measurements of f meson at KEK-PS.
The only one measurement on medium modification of f meson.
bg<1.25 (Slow)
Decays outside nucleus
R. Muto et al., PRL 98(2007) 042581
Decays inside nucleus
Cu
fmeson has NO mass
modification
fmeson has mass
modification
Blue line shows expected line
shape including all
experimental effects
wo mass modification
Modification is
shown as an Excess
e+e- invariant mass
Indication of QCD-originated mass modification!
2013/10/30
Hadron Experiment, K. Ozawa
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Target/Momentum dep.
bg<1.25 (Slow)
1.25<bg<1.75
Two nuclear targets:
Carbon & Copper
Inside-decay increases in
large nucleus
Momentum bin
Slowly moving f mesons
have larger chance to
decay inside nucleus
Excess
Same as
previous
slide
Only one momentum bin
shows a mass modification
under the current statistics.
To see clear mass modification
and establish QCD-originated
effects, significantly larger
statistics are required.
2013/10/30
Hadron Experiment, K. Ozawa
e+e- invariant mass
32
KEK-PS E325で得られたもの
• 原子核中でのφ中間子の質量分布変化を示唆する
データ
• 得られた分布をφ中間子の質量ピーク位置の変化とし
て解釈すると、3%の変化
• 初田-Lee予想とConsistentだが、偶然かもしれない。
– 核子内の<ss>凝縮量は、非常に小さいというLatticeの計
算（H. Ohki et. al, Phys. Rev. D 78(2008) 054502）
– 密度に対する凝縮量の線形近似
– 中間子生成過程、 中間子崩壊点の密度の不定性
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Hadron Experiment, K. Ozawa
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次に、何を目指すか？
• KEK-PS E325の結果のConfirm
– 世界的にも、他にφ中間子の結果は得られていない。
• 原子核密度における質量分布の確立
– 凝縮量との関係に対する議論に耐えられるデータ
– 生成過程、密度分布などの不定性の小さいデータ
• 単なる質量分布を超えた測定
– 媒質中で質量に対応するものは、エネルギーと運動
量の分散関係
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Hadron Experiment, K. Ozawa
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J-PARCでの実験の目標
A clear shifted peak needs to be identified
to establish QCD-originated effects
Momentum Dependence
Pb
E325 results
Proton
2013/10/30
Extrapolate
Hadron Experiment, K. Ozawa
凝縮量の評価を可能にする高統計測定
35
さらに、
Modified f
f
f
f
ff f
f
Pb
f
f
f from
Proton
[GeV/c2]
Invariant
mass in
medium
2013/10/30
Dispersion relation
Hadron Experiment, K. Ozawa
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Experimental set up
Construct a new beam line and new spectrometer
Deliver 1010 per spill proton beam
Primary proton (30GeV) beam
Cope with 1010 per spill beam intensity (x10)
Extended acceptance (90 in vertical) (x5)
Increase cross section (x2)
New high momentum beam line
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Hadron Experiment, K. Ozawa
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Detector components
HBD (Hadron-Blind
Cherenkov detector )
GEM Tracker
100x100 200x200
300x300
Position resolution of 100mm is achieved



Key Technology:
CsI evaporated GEM as a photo cathode
Q.E. of 40% is achieved
Both detectors based on Gas Electron Multiplier (GEM) technology
Recently, we succeed making a proto-type which meets our experimental
requirements.
Now, we are preparing a mass production of detectors.
2013/10/30
Hadron Experiment, K. Ozawa
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E29:f bound state?
Mass shift of f in nucleus can produce a bound state?
Production
pp -> ff
Detection
fp -> K+L
s
s
u
p u
J. Yamagata-Sekihara, D. Cabrera, M. J. Vicednte-Vacas, S. Hirenzaki;
d
'Formation of Φ mesic nuclei'; Progress of Theoretical Physics 124, 147-162 (2010).
Φ
2013/10/30
Hadron Experiment, K. Ozawa
s K+
u
s
u
d
Λ
39
E26: Omega in nucleus
p
n
w
g
mw 
g
p0
Measurements of w meson in nucleus
Production of w is also measured
Focus on low momentum w meson
H. Nagahiro et al,
Calculation for 12C(p-, n)11Bw
p-A  w + n+X
g
p0g
gg
p p + p g 2
Construct
Neutron counter
Gamma Detector
Beam Momentum is 2.0 GeV/c
It can be done at K1.8 and
also at new high momentum beam line
2013/10/30
Missing Mass
(Bound state?)
Invariant Mass
Hadron Experiment, K. Ozawa
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ハドロン内部構造
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Hadron Experiment, K. Ozawa
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アイソスピン対称性・クォークモデル
陽子： ｜1/2, ＋1/2＞, S = 0
中性子：｜1/2, －1/2＞, S = 0
π中間子： I=1の3重項, S = 0
Baryon
但、クォークの数を３つとする原理的理由はない。
2013/10/30
p+p, p-p反応の断面積
Particle Data Book, Phys. Let. B667(2008), 1
Hadron Experiment, K. Ozawa
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E19:Penta quark - results
2010 data
Search for the Θ+ via the p+π-→K-+X Reaction at 1.97GeV/c
No peak of + was observed.
U.L. (90%CL) 0.26mb/sr (2－14°) in 1.51－1.55GeV/c2
U.L.(90%CL) of G
0.72 MeV (1/2+)
3.1 MeV (1/2-)
PRL 109 (2012) 132002
PRL published
Updated data with higher beam momentum exists.
See Dr. Naruki’s talk.
2013/10/30
Hadron Experiment, K. Ozawa
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H dibaryon search (E42)
• The observation of several double-L
hypernuclear events in nuclear emulsion
suggests that the H-dibaryon is very
closely bound or unbound relative to 2mL .
Experimental
• Some experimental results show an
setups
enhancement just above 2mL mass (~
2250 MeV/c2).
– J.K. Ahn et al., PLB 444 (1998) 267
– C.J. Yoon et al., PRC 75 (2007) 022201(R)
• Weakly-bound : H -> Lpp
• Virtual state : LL threshold effect
Expected spectrum for a virtual state
• Precise measurements of LL and Lpp
productions in 12C(K-, K+) reactions are
proposed.
– Forward K spectrometer and a time
projection chamber around the target is
used.
2013/10/30
Hadron Experiment, K. Ozawa
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クォーク・反クォーク ポテンシャル
Coulomb Potential (Positronium)との比較
2013/10/30
Charmonium （c-c） の励起状態
Oscillator型
Martin and Shaw, Particle PhysicsHadron Experiment, K.Harmonic
Ozawa
Potentialの励起状態
q-q ポテンシャル
実線：-a/r + br、破線: a・ln(br)
45
Diquarks
Baryons as well as Mesons seem to be well described by a
Rotating String Configuration with a universal string tension.
M2 (GeV2)
10
9
Baryons
8
M2∝1.1L
7
10
Mesons
9
8
M2∝1.1L
7
6
6
5
5
4
4
N
Delta
Lambda
Sigma
Xi
3
2
1
rho/a
omega/f
phi/f
K*
3
2
1
0
0
0
1
2
3
4
5
6
L
7
0
1
2
3
4
5
6
L
7
Emergent Diquarks
Baryons as well as Mesons seem to be well described by a
Rotating String Configuration with a universal string tension.
“diquark”
in low-lying modes
qq
q
l: orbital motion
r: di-quark correlation
Heavy quark baryon
•
•
•
When single quark picture is
still a good picture, excited
states are degenerated.
If Cqq (q=u,d) system is
considered as C and di-quark
correlations, orbital motion of
l is lowered due to the
collectivity of the di-quark
motion.
Spin correlations between
light quarks give additional
level separations.
Level pattern tell us:
Mass of di-quark
Strength of di-quark
correlation
Spin dependent correlation
between light quarks
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Measurements of all levels are important
Hadron Experiment, K. Ozawa
Missing mass Spectroscopy
2.3 Tm Dipole
PID
Use forward D mesons
production
No Bias measurements
up to 3GeV/c2 of
Charmed Baryon mass
H2 TGT
Beam pDC
High rate
Trackers
(Fiber, SSD)
K+
DC PID
p-
p-
TOF
LAMPS
• Large Acceptance, Multi-Particle
– K, p from D0 decays
– Soft p from D*- decays
– (Decay products from Yc*)
• High Resolution
• High Rate
– SFT/SSD op. >10M/spill
at K1.8
Hadron Experiment, K. Ozawa
2013/10/30
49
Expected Spectrum in the (p,D*-) reaction
(GeV/c2)
Signal: 1 nb/Yc* :~1000 events
BG: 1.8 mb (JAM)
2.6
Lc(2625) 3/2Lc(2595)
1/2pLc
2.4
2.3
Lc
Lc
1/2+
Lc + 0.8GeV
DN
2.8
2.7
Sc(2800) ??
D*N
Lc(2880)
Lc(2940)
Lc(2880)
5/2+
DN
Lc(2765)
Sc(2800)
2.9
pSc
D*N
Sc(2455)
Sc(2520)
Lc(2595)
Lc(2625)
Lc(2940) ??
pSc
Sc(2520) 3/2+
Sc(2455) 1/2+
Missing Mass (GeV/c2)
Summary
• Several experiments are being performed and
prepared at J-PARC to investigate hadron
interactions, nuclear medium effects and
internal structure of hadrons.
• Currently, strangeness nuclear physics and
Kaon bound system are intensively studied. In
near future, meson properties in nucleus and
level structure of charmed baryons will be
measured.
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Hadron Experiment, K. Ozawa
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