加速器を用いた ハドロン物理実験
DESCRIPTION
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. Tokai, Japan. 50 (30) GeV Synchrotron (15 m A). Material and Biological Science Facility. 3 GeV Synchrotron (333 m A). Hadron Hall. 400 MeV Linac (350m). - PowerPoint PPT PresentationTRANSCRIPT
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加速器を用いたハドロン物理実験K. Ozawa (KEK)
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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
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J-PARC (Japan Proton Accelerator Research Complex)
Tokai, Japan
50 (30) GeV Synchrotron (15 mA)
400 MeV Linac (350m)
3 GeV Synchrotron (333 mA)
Material and Biological Science Facility
World-highest beam intensity : ~1 MW x10 of BNL-AGS, x100 of KEK-PS
Neutrino Facility
Hadron Hall60m x 56m
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Nuclear & Hadron Physics at J-PARC
L,X N
ZL, S Hypernuclei
LL, X Hypernuclei
Stra
ngen
ess
0
Hypernuclei
-1
-2
Proton Beam
K1.8
KL
K1.1BR
High p (not yet)SKS
K1.8BRK1.1
d
uu
d
s
Pentaquark +LLHe6
Free quarks Boundquarks
Why are bound quarks haevier ?
Quark
Mass without Mass PuzzleKaonic nucleusKaonic atom
X ray
K−
Implantation ofKaon and the
nuclear shrinkage
K meson
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KL
K1.1BR
North side
South sideH
igh Mom
entum
SKS
K1.8BR
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SKS Spectrometer
Q10 Q11
Q12Q13
D4
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核構造とストレンジネス
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原子核構造
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)
1 体ポテンシャルによる励起準位
調和振動子
井戸型
ウッド・サクソン
励起準位(調和振動子、井戸型)2013/10/30 Hadron Experiment, K. Ozawa 8
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ストレンジネス
1 体ポテンシャルによる励起準位
PRC 64 (2001) 044302
-> UL = - 28 MeV (c.f. UN = -50 MeV)
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
2013/10/30 Hadron Experiment, K. Ozawa 9
束縛エネルギーは、違っていた。
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ストレンジネス束縛エネルギーPRC 64 (2001) 044302
-> UL = - 28 MeV (c.f. UN = -50 MeV)
束縛エネルギーの違いがもたらす物理
Experimental input to models
Schaffner-Bielich, NP A804 (2008).
Baryon fraction in neutron star
One example…
More experimental information on LN, XN, LL, SN interactions are awaited.
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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
LHe : Large CSB is suggested
– sd-shell hypernuclei for A-dependence of LN interaction• 19
LF : The first sd-shell hypernuclei
– Confirm LN spin-dependent forces and study LN-SN coupling force
• 10LB and 11
LB
• Physics: g-factor of L in nucleus– Spin-flip B(M1) measurement for gL in a nucleus
• 7LLi : Least ambiguities and most reliable.
• Hyper Ball-J is almost ready and we will take the first experimental data soon.
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Beam
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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 L6
LHe
• 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.
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Experimental Method(Nuclear Emulsion)
The experiment is under preparations and it will be performed in the end of this year or early next year.
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XN interaction (E05)
• Discovery of X-hyper nucleus using 12C(K-,K+) reaction– 12
XBe
• 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
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Expected Spectrum (Will be improved using a new spectrometer)
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ハドロンーハドロン相互作用2013/10/30 Hadron Experiment, K. Ozawa 14
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バリオンーバリオン相互作用
Example : 陽子・中性子・重陽子の性質
図は、八木浩輔・原子核物理学
中性子・陽子散乱の角分布
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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。
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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”
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meson exch
quark + meson exch
Evaluation of quark Pauli effect and understanding the origin of the hard core of the nuclear force
S+p (quark Pauli)
Hyperon production 1.3 GeV/c p+- p -> K+ S+- reaction S+- track not directly measured Measure proton momentum vector -> kinematically complete
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 )
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Physics motivation
Experimental setup
Experimental scheme
Experiment is on-going2013/2/11 J-PARC Future 2013, K. Ozawa
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Results of an engineering runXY plane YZ plane
Liquid 4He insideTarget-image together with material around
has been reconstructed by the CDSCharged particles from the target have been successfully identified by the CDS
18
pp- invariant-mass spectra reconstructed
by the CDSL
~10,000 Ls have been accumulated2013/10/30 Hadron Experiment, K. Ozawa
CDS and Liquid Helium target system successfully worked
Ready to explore kaonic-nuclei @ K1.8BR
Data Taking in this May!
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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
• Semi-exclusive measurement by Range Counter Array (RCA) in order to suppress quasi-free B.G.– 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
np K-ppd
Λ*π+ K+
RCA
K+
p
2013/10/30 Hadron Experiment, K. Ozawa Missing mass d(π+,K+) [GeV/c2]
Momproton>350MeV/c
coun
ts (/
3M b
eam
・10da
ys )
Expected point by FINUDA, DISTOData already collected and
results will be reported soon.
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原子核媒質とメソン2013/10/30 Hadron Experiment, K. Ozawa 20
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Mas
s [G
eV]
媒質からの励起状態としてのハドロン
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NG ボソンとしての擬スカラー中間子( Jp=0- )
構成子クォークの質量を獲得
• カイラル対称性の自発的破れに伴う質量の獲得• 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
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p 束縛状態
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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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Exp. Results
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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 normalnuclear density (r = r0 ) is indicated.
Experiment is continued at RIKEN and positive results are already obtained.
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Other Pseudo Scalar Meson: h
2013/10/30 Hadron Experiment, K. Ozawa
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.
In addition, measurements of invariant mass of N* decay
Simulation
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Other Pseudo Scalar Meson: h’ @ GSI
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Reaction is similar with pionic atom experiment.
Theoretical calculation by H. Nagahiro
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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
– 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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Hatsuda, Koike and Lee, Nucl. Phys. B394 (1993) 221Kapusta and Shuryak, Phys. Rev. D49 (1994) 4694
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Example: sum rulee.g. Weinberg type QCD sum rule
Hatsuda, Koike and Lee, Nucl. Phys. B394 (1993) 221Kapusta and Shuryak, Phys. Rev. D49 (1994) 4694
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ALEPH, Phys. Rep. 421(2005) 191
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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• 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2013/10/30 Hadron Experiment, K. Ozawa 28
Hatsuda and Lee, Phys. Rev. C46 (1992) R34
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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
– 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
– 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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Hatsuda and Lee, Phys. Rev. C46 (1992) R34
Hatsuda and Kunihiro, Nucl. Phys. B387 (1992) 715
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KEK-PS E325 実験の概要
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12 GeV proton induced. p+A ® f + X
Electrons from f decays are detected.
TargetCarbon, Cupper0.5% rad length
KEK E325
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Clear measurements of f meson at KEK-PS.
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R. Muto et al., PRL 98(2007) 042581
Indication of QCD-originated mass modification!
Cu
bg<1.25 (Slow)
e+e- invariant mass
Decays inside nucleusDecays outside nucleus
fmeson has mass modification
Modification is shown as an Excess
fmeson has NO mass modification
Blue line shows expected line shape including all experimental effectswo mass modification
The only one measurement on medium modification of f meson.
Hadron Experiment, K. Ozawa
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322013/10/30
Target/Momentum dep.bg<1.25 (Slow) 1.25<bg<1.75
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.
e+e- invariant mass
Two nuclear targets:Carbon & CopperInside-decay increases in large nucleus
Momentum binSlowly moving f mesons have larger chance to decay inside nucleus
Same as previous slide
Excess
Hadron Experiment, K. Ozawa
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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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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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J-PARC での実験の目標
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Pb
Proton
A clear shifted peak needs to be identified to establish QCD-originated effects
Momentum Dependence
E325 results Extrapolate
Hadron Experiment, K. Ozawa凝縮量の評価を可能にする高統計測定
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さらに、
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Pb
fModified f
[GeV/c2]
f from Proton
Invariant mass in medium
ff
fff
ff
fp dep.
Dispersion relation
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Experimental set up
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Cope with 1010 per spill beam intensity (x10)Extended acceptance (90 in vertical) (x5)Increase cross section (x2)
Construct a new beam line and new spectrometer
Deliver 1010 per spill proton beam Primary proton (30GeV) beam
New high momentum beam line
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Detector components
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100x100 200x200 300x300
Position resolution of 100mm is achieved
GEM Tracker
HBD (Hadron-Blind Cherenkov detector )
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.
Key Technology:CsI evaporated GEM as a photo cathodeQ.E. of 40% is achieved
Hadron Experiment, K. Ozawa
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E29: f bound state?
2013/10/30 Hadron Experiment, K. Ozawa
ssuud
K+
Λ
Φ
p ud
sus
fp -> K+L
pp -> ff
39
Mass shift of f in nucleus can produce a bound state?
Production
Detection
J. Yamagata-Sekihara, D. Cabrera, M. J. Vicednte-Vacas, S. Hirenzaki; 'Formation of Φ mesic nuclei'; Progress of Theoretical Physics 124, 147-162 (2010).
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E26: Omega in nucleus
2013/10/30 40
g g
gp
w p0
n
p-A ® w + n+X
gg
p0g
2ppm gpw +
Measurements of w meson in nucleusProduction of w is also measuredFocus on low momentum w meson
ConstructNeutron counterGamma Detector
Beam Momentum is 2.0 GeV/cIt can be done at K1.8 and also at new high momentum beam line
Hadron Experiment, K. Ozawa
H. Nagahiro et al, Calculation for 12C(p-, n)11Bw
Missing Mass(Bound state?)
Invariant Mass
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ハドロン内部構造2013/10/30 Hadron Experiment, K. Ozawa 41
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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 = 0π 中間子: I=1 の 3 重項 , S = 0
p+p, p-p 反応の断面積Particle Data Book, Phys. Let. B667(2008), 1
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 Hadron Experiment, K. Ozawa 42
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E19:Penta quark - results 2010 data
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-)
Search for the Θ+ via the p+π-→K-+X Reaction at 1.97GeV/c
PRL 109 (2012) 132002
PRL publishedUpdated data with higher beam momentum exists.See Dr. Naruki’s talk.
2013/10/30 43Hadron 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 .
• Some experimental results show an 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
• 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.
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Expected spectrum for a virtual state
Experimental setups
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クォーク・反クォーク ポテンシャル
Harmonic Oscillator 型Potential の励起状態
Coulomb Potential (Positronium) との比較
Charmonium ( c-c ) の励起状態Martin and Shaw, Particle Physics
q-q ポテンシャル実線: -a/r + br 、破線 : a ・ln(br)2013/10/30 Hadron Experiment, K. Ozawa 45
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Diquarks
0 1 2 3 4 5 6 70
1
2
3
4
5
6
7
8
9
10
NDeltaLambdaSigmaXi
0 1 2 3 4 5 6 70
1
2
3
4
5
6
7
8
9
10
rho/aomega/fphi/fK*
Baryons Mesons
LL
M2 (
GeV2 ) M2 1.1∝ L M2 1.1∝ L
Baryons as well as Mesons seem to be well described by a Rotating String Configuration with a universal string tension.
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Emergent DiquarksBaryons as well as Mesons seem to be well described by a
Rotating String Configuration with a universal string tension.
“diquark”in low-lying modesqq
q
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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.
2013/10/30 48
l: orbital motionr: di-quark correlation
Hadron Experiment, K. OzawaMeasurements of all levels are important
Level pattern tell us:Mass of di-quark Strength of di-quark
correlationSpin dependent correlation
between light quarks
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Missing mass Spectroscopy
• 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
2.3 Tm Dipole
H2 TGT
Beam p-
PID
p-
K+DC
TOF
PID
p-
DCHigh rate Trackers(Fiber, SSD)
LAMPS
Use forward D mesons productionNo Bias measurements up to 3GeV/c2 of Charmed Baryon mass
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Signal: 1 nb/Yc* :~1000 eventsBG: 1.8 mb (JAM)
Lc 1/2+
Sc(2455) 1/2+
Sc(2520) 3/2+
Sc(2800) ??
Lc(2595) 1/2-
Lc(2625) 3/2-
Lc(2880) 5/2+
Lc(2940) ??
DN
pLc
(GeV/c2)
D*N
2.3
2.4
2.7
2.9
2.6 pSc
2.8
Expected Spectrum in the (p,D*-) reaction
Lc
S c(2
455)
S c(2
520) Lc(2
625)
Lc(2
765)
Lc(2
880)
Lc +
0.8
GeV
Missing Mass (GeV/c2)
pSc DN D*N
Lc(2
595)
S c(2
800) Lc(2
940)
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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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