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Hadron Spectroscopy with high momentum beam line at J-PARC
K. Ozawa (KEK)
ContentsCharmed baryon spectroscopyNew experiment at J-PARC
On-going Joint Project• Joint project between J-PARC theory center,
KEK, and RCNP. – Proposing construction of new high-momentum
high-resolution beam line
• Collaboration– H. Kamano, T. Nakano, H. Noumi, A. Hosaka
(RCNP), T. Sato (Osaka)– M. Oka, T. Hyodo (TIT), D. Jido(Kyoto)– K. Ozawa, S. Yasui (KEK)
2012/2/10 2Future prospect of Hadron physics
Hadron Physics
• Origin of Hadron interaction?– Nuclear Force inside nuclei– Meson-Baryon, Baryon-Baryon interaction
• Property of Nuclear (QCD) matter?– Origin of hadron mass– Neutron Star
• Inside structure of Hadron? – Naïve quark model needs to be extended– Roper, Penta quark , Exotic mesons @ Belle
2012/2/10 3Future prospect of Hadron physics
Beyond the quark model
• According to the naïve quark picture, the first excited state should be negative.
• However, observed state is positive. (It’s called Roper.)– Long standing problem
• In addition, several exotic hadrons are observed recently.
Roper
Exotics Width v.s. Mass[MeV] of Excited Nucleon
Belle, PRL 99(2007), 142002Y LEPS, PRC 79, 025210Θ+
Need further study.2012/2/10 4Future prospect of Hadron physics
Issues and Solution
• Several effects are competed in light hadrons – Gluon interaction , Chiral properties, Di-quark
correlation, Three body effects, Spin dependent interaction, Dynamical orbital excitation
• Current experimental data includes all above effects. – Every effect should be measured separately.
• Heavy Quark spectroscopy is key!– Many of above complex effects are suppressed.
– Spin dependent interaction, Three body effects, Chiral effects
C2012/2/10 5Future prospect of Hadron physics
Charmed Baryons• Wccc : Triple charmed baryon
– It only have color interactions.– Experimentally, it’s not observed yet.
• Xcc : Doubly charmed baryons – Effects of chiral symmetry are suppressed. – Other effects can be studied easily. – One experiment (SELEX) reported.– It can be produced at J-PARC.
• L+c, Sc : Charmed baryons– Spin dependent interaction is suppressed– Interactions can be simplified. – Let’s start here!2012/2/10 Future prospect of Hadron physics 6
C
CCCCC
Single charmed Baryons
2012/2/10 Future prospect of Hadron physics 7
Predicted states using a quark model(L.A. Copley et. al, Phys. Rev. D 20 (1979) 768) Observed charmed baryons
Lc p
Sc p
DN
Threshold
Several states are missing
Di-quark correlation?
2012/2/10 Future prospect of Hadron physics 8
Charmed baryon system can be understood as Heavy Quark – di-quark system
?“Roper”
In addition, exotics in charm sector
2012/2/10 Future prospect of Hadron physics 9
• If exotic baryons exist in charm sector, it can be observed easily compared to light quarks.– Narrow width– Large mass window below DN threshold
Candidate of exotics Mass window
for exotics
Charm Baryon spectroscopy @ J-PARC
• Mass Spectra of excited charmed baryon contains basic information of quark interaction
• Many states are still missing– Few states are observed in invariant
mass plot.• Observed states has relatively
narrow width – Good for spectroscopy!
Roper candidate
Observed charmed baryons2012/2/10 10Future prospect of Hadron physics
Several missing states and exotic candidates Observe all excited states of
single charmed baryon below 3 GeV.
Purpose
New Experiment @ J-PARC
2012/2/10 Future prospect of Hadron physics 11
p- p -> S0c + D0
p+ n(d) -> L+c + D0
D0 -> p+ K-
Detect p, K and reconstruct D meson. Then, missing mass is calculated.
Dispersive Focal PointDp/p~0.1%
Construct new high resolution, high momentum beam line
Beam
Experimental Setup
• Magnetic field: 1 [T]• 50% of D meson can be detected• Poor mom. res. at very forward
Candidate 1: Solenoid type
Candidate 2: Dipole type
f2m
2m
p- p -> S0c + D0
p+ n(d) -> L+c + D0
D0 -> p+ K-
Detect p, K and reconstruct D meson. Then, missing mass is calculated.
Size of Gap
2m
• Magnetic field: 1 [T]• 50% of D meson can be detected
1m
1m
Size of inside coil
2012/2/10 12Future prospect of Hadron physicsParticle identification and trigger scheme are issues for both cases.
dp/p ~ 1% is required
Kinematics & Acceptance• Beam Momentum: 15GeV/c• Lc (2940 ) (Roper candidate) is assumed.
2012/2/10 Future prospect of Hadron physics 13
p from D0 decays
K acc. is similar
Both p and K are in acceptance
Solenoid D-magnet
PT PZ
[GeV/c]0 1 0 42
[GeV/c]8
Momentum Resolution
2012/2/10 Future prospect of Hadron physics 14
• Beam Momentum: 15GeV/c• Lc (2940 ) (Roper candidate) is assumed.
p from D0 decays
K is similar
Both p and K are in acceptance
Solenoid D-magnet
DpZ/ pz
D-magnet configuration has better momentum resolution.Further check for the calculation is needed.
0 0.1-0.1
Dx = 100mm
2012/2/10 Future prospect of Hadron physics 15
PT PZPT PZ
p from L decays Proton from L decays
PT PZPT PZ
Decay products from Lc
p from Lc(2940) 3body decays p from Lc(2286) decays
Decayed products can be measured using the same configuration.
Summary• To understand structure of light hadrons,
charmed baryon spectroscopy is an important tool.
• charmed baryon spectroscopy can give basic information about Roper state, Exotic state, and di-quark correlations.
• A new beam line and new experiment is proposed to perform charmed baryon spectroscopy.
2012/2/10 Future prospect of Hadron physics 16
Physics topics @ new beam line
• Charm baryon bound state• Color transparency • Short range structure • Drell-Yan process (P04)• c-bar c contents in nuclei• Multi-fragmentation • omega bound state (E26) and eta’• Basic cross section of pi N -> pi pi N• Exotic in light quark • Mass modification of f (E16)• Heavy ion physics2012/2/10 Future prospect of Hadron physics 17
Note: Existing experimental results• Currently, charmed baryons are identified using its decays in
collider experiments.
2012/2/10 Future prospect of Hadron physics 19
BaBar, Lc -> LK0sK+
(Phys. Rev. D72 052006)
N ~ 4600
• Our experiment measure productions of baryons and it gives different information.
• Statics will be similar • Intensity of 107 ~ 108 / spill
• Sensitive to relatively wide width states• Background will be suppressed at
threshold region.
• Exclusive measurements can be done. • Decays can also be measured.
The J-PARC E16 spectrometer
20
X 26
Magnet (used for KEK E325)
Candidates of large D-magnet spectrometer
Cross Section & Yield
• No reliable calculation in such threshold region– At least, 10 nb can be assumed.
• Yield – Lq H2 1g/cm2
– 107 / spill, 6 second– 1 baryons per spill
• D meson Branch and acceptance – 1%
• Integrated Yield per month – ~ 102 per month
2012/2/10 Future prospect of Hadron physics 21