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Hadron physics experiments at J‐PARC
K. Ozawa (KEK)
2014/8/22 K. Ozawa, CNS Summer School 1
Contents• Introduction
– What is hadron physics?– What is J‐PARC?
• Experiment at J‐PARC I – Charmed Baryon Spectroscopy
• Experiment at J‐PARC II– Meson properties in nucleus
2014/8/22 K. Ozawa, CNS Summer School 2
Hadron and Hadron Physics• Hadron is a particle which have a “strong interaction”– Baryons, such as protons, neutrons– Mesons, such as mesons, mesons, … – Naively speaking, particles which consist of “quark”s
• So many hadrons are observed by now
• Hadron physics is a natural extension of nuclear physics to study following topics– Internal structure of baryons and mesons– Origin of interactions between hadrons– Nucleus as a nuclear matter
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Quarks
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Proton
Currently, observed quarks
u
u d
up charm top
down strange beauty
• There are three generations. The second and third generations have the same role, but heavier masses.
• Using heavier quarks, nucleus and hadron interactions can be studied using a different way.
Charge +2/3
Charge ‐1/3
1Generation 2 3
Light Heavy
Our world consists of up and down quarks
Example: Strangeness Nuclear Physics
• Let’s think about baryons which contain a strange quark.
• Such baryons can avoid a “Pauli‐blocking” and we can put it deep inside a nucleus.
• Such baryons have a similar energy state with a nucleon and we can study nucleon state levels in nucleus directly.
• At KEK‐PS, an experiment is performed to study baryon states in nucleus.
2014/8/22 K. Ozawa, CNS Summer School 5
PRC 64 (2001) 044302
‐> U = ‐ 28 MeV(c.f. UN ~ ‐50 MeV)
Strange baryon () states measured at KEK_PS
Energy States are clearly seen.Binding Energy is different
It is important as a basic information for a neutron star
Requirements for experiments• To perform such experiments, we need
– Relatively high energy beam • Pair production of strange quarks ~ 1000 MeV• Charm quark ~ 3000 MeV
– High intensity • To cope with small cross section
– Several beam species• meson, Strange meson (K meson), Anti‐proton, muon
• To achieve such requirements, we construct an accelerator complex– Japan Proton Accelerator Research Complex (J‐PARC) provides a high intensity proton beam and generate several secondary beams
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J-PARC (Japan Proton Accelerator Research Complex)
J-PARC (Japan Proton Accelerator Research Complex)
Tokai, JapanTokai, Japan
50 (30) GeV Synchrotron (15 A)
400 MeV Linac (350m)
3 GeV Synchrotron (333 A)
Material and Biological Science Facility
World-highest beam intensity : ~ 1MW x10 of BNL-AGS, x100 of KEK-PS
Neutrino Facility
Hadron Hall60m x 56m
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30 GeV Accelerator & Hadron Experimental Facility
2014/8/22 K. Ozawa, CNS Summer School 8
Branch Point from Acc. to Hadron
Transfer Line from Acc. to Hadron
Hadron Experimental Facility
Current Production target for secondary beams
New Beamline (under construction)
K. Ozawa, CNS Summer School 9
Hadron Experimental Facility
K1.8BR
KL
K1.8
K1.1High-p
COMET
Name Species Energy IntensityK1.8 ±, K±
KL
North side
South side
SKS
K1.8BR
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New Beam Line is under construction
Construction of New Beam Line is on‐going. Multi Purpose beam line for following beams
Primary Proton Beam (30GeV), 1010‐12 per spillHigh Momentum un‐separated secondary beam (20GeV/c), 108 per spillPrimary Proton Beam (8GeV) for COMET
PhysicsHadrons in nucleusHadron spectroscopy mu‐e conversion (COMET)
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In this lecture, I will introduce new experiments using a new beam line.
Experiments @ new beam line
• Internal Structure of Hadron– Charmed baryon spectroscopy can provide essential information, especially for Di‐quark correlations
• Hadrons in nucleus– Hadron mass is dynamically generated and strongly related with nuclear medium properties.
– Experimental information of hadron mass in nucleus
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INTERNAL STRUCTURE OF HADRON (PROTON, PION, … )
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Structure of proton and meson• Several experimental data
support existence of quarks in proton and meson– Electron‐proton scatterings
show internal structures• R.W. McAllister and R.
Hofstadter, Phys rev. 102(1956), 851
• M. Breidenbach et al., Phys. Rev. Let. 23(1969), 935
• “Quark model” including strange quark explains existing baryons and mesons very well – Proton and baryons contain
three quarks– Mesons contain quark – anti‐
quark
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Spin 0
Baryon
Spin 1/2
Meson
Spin 3/23 3 3
3 3
Properties of interaction btw quarks• Measurements of excitation states are always a good method to study a structure.
• Especially, meson is a two‐body system and excitation states can be measured as excited resonances.– Measurements of charmonium (charm – anti‐charm mesons)
2014/8/22 K. Ozawa, CNS Summer School 15
Observed charmonium states
A potential btw anti‐quark and quark is evaluated as a/r+b*r (a,b const.).
Baryons• Quark‐quark interactions and inside structure of baryons are also studied using excited states.
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Summary table in S. Capstick, N. Isgur, PRD34 (1986) 2809• However, it is difficult to
extract detailed properties of quark interactions – A Baryon contain three
quarks and it should have many body effects
– Large width due to strong coupling to meson
• Naïve quark model can’t explain the current experimental data– Additional effects should
be consideredColored: Observed stateBars: Model Prediction
Di‐quark correlation• One of possible strong effects is a quark‐quark (Di‐quark)
correlationColor‐Magnetic Interaction of two quarks
VCMI~[s/(mimj)]*(ij)(ij)
“Good Diquark”: Strong Attraction
VCMI(1S0, ͞3c) = 1/2*VCMI(1S0, 1c)[qq] [͞qq]
• Diquarks are emerged due to the color magnetic interaction between two quarks.
• The so‐called “good diquark” has a color anti‐symmetric 3bar and spin singlet configuration. It’s strong enough.
• One expects that a “qood diquark” may be formed in a baryon.
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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.
M2~LA distance of [qq]‐q/ ͞q‐q increases as L increases.
q
͞q
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q
L L
Emergent Diquarks
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4 5 6 7
NDeltaLambdaSigmaXi
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4 5 6 7
rho/aomega/fphi/fK*
Baryons Mesons
LL
M2(GeV
2 ) M2∝1.1L M2∝1.1L
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 modes
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qA diquark-quark picture of baryons seems valid in low-lying modesHowever, it is difficult to study strength of a di-quark correlation only using light quarks, because all combination of qq contribute and interfere.
Charmed Baryon
Q
Weak Color Magnetic Interactionwith a heavy Quark
• [qq] is well Isolated and developed
• Level structure of Yc* provides diquark properties• “diquark mass”
VCMI~[s/(mimj)]*(ij)(ij)
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Level Structure and motion• 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 is lowered due to the collectivity of the di‐quark motion.
• Spin correlations between light quarks give additional level separations.
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: orbital motion: di‐quark correlation
K. Ozawa, CNS Summer School
Measurements of all levels are important
Level pattern tell us:Mass of di‐quark Strength of di‐quark correlationSpin dependent correlation between light quarks
c 1/2+
c(2455) 1/2+c(2520) 3/2+
c(2800) ??
c(2595) 1/2‐
c(2625) 3/2‐
c(2880) 5/2+
c(2940) ??
DN
c
(GeV/c2)
D*N
2.3
2.4
2.7
2.9
2.6c
Limited # of Charmed Baryons have yet been observed.
mode
mode
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New Experiment:Charmed Baryon Spectroscopy
Using Missing Mass Techniques
D0(Yc’)
p
Inclusive p(‐,D*‐) Yc*+
p(‐,D*‐p)D0
Yc*+( p(‐,D*‐)Yc’ ) (Target)
Charmed baryons are observed in the missing mass spectrum using p(‐,D*‐) Yc*+ reaction.In addition, the decay mode can be identified
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What we will measure
• Production Rate: reflect quark configurationHeavy quark + light diquark
• Spectrum identified by productions Basic modes of diquark motions (λ/ρmodes) Spin (Heavy Quark) multiplets
• Decay propertiesM(Qqbar) + N(qqq) / m(qqbar) + Yc(Qqq)
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Production
p Yc*
L
D*
D*, D
One‐step, t‐channel dominant
λmodes are excited by a simple mechanism• HQ spin doublet• Spin/Parity from Production Ratio
Note: Production Cross Section does not go down at higher L due to large effective momentum transfer
arXiv: 1405.3445
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2014/8/22 K. Ozawa, CNS Summer School 27SU(3) limit Heavy Quark (HQ)
• • •
• • •
MQ mq MQ mqSU(3) limit Heavy Quark (HQ)
L = 1
L = 2
L = 1
L = 2
isotope shift ‐dep. int.
5/2+3/2+
3/2‐1/2‐
L = 01/2+
A heavy quark differentiates diquarkmotions = modes and modes are distinct ~ isotope shift
HQ doublet
HQ doubletIn the heavy quark limit, the heavy quark spin decouples to the others.
HQ doublet HQ doublet
L = 1 L = 2L = 0
1/2‐ 3/2‐ 5/2+ 3/2+1/2+
1 : 2 3 : 2
c c(2595)
c(2800)
cc*
c(2625)
c(2880)
c(2940)
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Decay Properties
qqQ
qqq
mode (qq) mode [qq]c ) > pD) c ) < pD)
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Dispersive Focal Point(DP)p/p~0.1%
Collimator (IF)
15kW Loss Target
Exp. TGT(FF)
SpectrometerT1
QQQQD
QQD D
D D DQ
QQSS S
DD QQD
DQQ
Magnet:D : DipoleQ : QuadrupoleS : Sextupole
High‐res., High‐mom. Pion Beam• High‐intensity secondary Pion beam can be delivered.
– 2 msr・%、1.0 x 107 Hz @ 15GeV/c • High‐resolution beam: p/p~0.1%
– Momentum dispersion and eliminate 2nd order aberrations
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Charmed Baryon Spectrometer
Large acceptance ~ 60% (for D*), ~85% (for decay +) Good resolution: p/p~0.2% at ~5 GeV/c
LH2‐target
Ring ImageCherenkovCounter
Internal DC
FM magnet s
Fiber tracker
Beam GC
Internal TOF
Internal TOFDC
TOF wall
2m
Decay p()
20 GeV/cBeam
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32
Summary for charmed baryon• Charmed Baryon Spectroscopy via the (,D*‐) reactions– Shed light on “diquark”: colored object in hadrons– Clarify a Level Structure of the charmed baryons
• From the ground state to highly excited states of Ex~1 GeV• Independent of decay final states
– Decay Branching Ratios (Partial Widths)• Suppressions of [qqbar]‐[qqQ] decays if “Good diquark” in Yc*• Possible assignment of spins
• A New Project of Hadron Physics at J‐PARCHigh‐res., High‐intensity 2ndary Beam– Large Acceptance, Multi‐Particle Spectrometer
2014/8/22 K. Ozawa, CNS Summer School