What are good building blocks of Hadrons?
description
Transcript of What are good building blocks of Hadrons?
Charmed Baryon Production(Charmed baryon Spectroscopy via p(p-,D*-)Yc)
11 Sep., 2013
H. NoumiRCNP, Osaka University
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What are good building blocks of Hadrons?
Constituent Quarkq
�͞ q
q
Diquark?[qq]
q(Colored cluster)
hadron (colorless cluster)q
�͞ q
q
How to form baryons?
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q
q
q
• Most fundamental question• Interaction btwn quarks Diquark correlations
• 3 [qq]-pairs in a Light Baryon
How to close up diquark correlations
Charmed Baryon
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Q
Weak CMI with a heavy Quark• [qq] is well Isolated and developed
• Level structure of Yc* • Decay Width/Decay Branching Ratios, etc.
VCMI ~ [as/(mimj)]*(li,lj)(si,sj)
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HydrogenTarget
p-
K+
p-
20 GeV/c p- Beam
DispersiveFocal Plane
High-resolution, High-momentumBeam Line D*- Spectrometer
-p p-*D
*cY
-p
-p+K
Missing Mass Spectrum
Missing Mass Spectroscopy
Measure D*-
Charmed Baryon Spectroscopy (P50)
Charmed baryon spectrometerModified design
FM cyclotron magnetJ-PARC E16
⇒ 2.3 Tm, 1 m gap
• High rate detectors Fiber, SSD
• Large detectors• Internal detectors
DC, RPC• PID: RICH
Hybrid radiator
p-LH2-target
Ring ImageCherenkovCounterInternal DC
FM magnetps
-
K+SSD
Fiber tracker
Beam GC
Internal TOF
Internal TOFDC
TOF wall
2m
Decay p+
Beam p-
Large acceptance multi-particle spectrometer system• Multi propose spectrometer
* D* tagging: > 106 reduction⇒Other event selection
○ Forward scattering angle cut
⇒ Reduction (2.2-3.4 GeV/c2) = 15 Signal acceptance = 0.54 1900 → 1000 counts
Background reduction 3
Kpqcm
qKp
qps
qD0ps
qpD*Reduction
S/N
qD0
0.000 2.000 4.000 6.000 8.000 10.000 0.000
2.000
4.000
6.000
8.000
10.000
12.000
14.000
16.000
18.000
Reduction for Signal: exp(bt)15×2.0×106 reduction background W/ signals
Background spectrum
Clear peak structure @ 1 nb/peak case *Main background structure is dominant.
⇒ Achievable sensitivity: 0.1-0.2 nb (3s level, G < 100 MeV)
SumMain BG(s-production+ Miss-PID)
Associated charm production BG
W/o signal
W/ signal: 1900 counts/peak W/ signal: 1000 counts/peak
W/o signal
Only D* tagging W/ event selection
Decay measurement
• Method: Mainly Forward scattering due Lorentz boost (q < 40°) Horizontal direction: Internal tracker and Surrounding TOF wall Vertical direction: Internal tracker and Pole PAD TOF detector
• Mass resolution: ~ 10 MeV(rms) Only internal detector tracking at the target downstream
• PID requirement: TOF time difference (p & K) ⇒ DT > 500 ps Decay particle has slow momentum: < 1.0 GeV/c
Beam Target
Magnet pole
Beam
Target
Internal tracker
Pole PAD TOF wallSurrounding TOF wall
Magnet pole
Basic performances• Acceptance
50-60%○ exp(bt) (t-channel, b = 2 GeV-2)
Yield @ 1 nb case: ~1900 counts○ 4 g/cm2 LH2 target, 8.64×1013 p- (100 days)○ eall = 0.55
Acceptance for decay particles: ~85%○ Lc(2940)+ → Sc(2455)0 + p+
○ Lc(2940)+ → p + D0
* Compare coverage cosq > -0.5
• Resolution Dp/p = 0.2% @ 5 GeV/c Invariant mass resolution
○ D0 : 5.5 MeV○ Q-Value: 0.7 MeV
Missing mass resolution○ Lc
+: 16.0 MeV○ Lc(2880)+: 9.0 MeV
Decay measurement○ DM ~10 MeV
exp(bt)
Isotropic in CM
Acceptance: D*- detection
Decay angle: Lc(2940)+ → Sc(2455)0 + p+
Forward direction(Beam direction)
Tagged missing mass spectra
*Full event w/ background @ 1 nb• Continuum background around the peak region• Signal counts
Sc p mode: ~230 counts p D mode: ~320 counts
Sc0 p+ Sc
++ p-
Lc+ p+ p- p D0
SUM
Signal
Main BG
Sc0 Sc
++
Lc+
D0
Tagged missing mass spectra
* Full event w/ background @ 1 nb• Selecting Lc
+ p+ p- decay chain Background level was drastically decreased.⇒• Signal counts
Sc p mode: ~230 counts ⇒ ~200 counts p D mode: ~320 counts
Sc0 p+ Sc
++ p-
Lc+ p+ p- p D0
SUM
Signal
Main BG
Sc0 Sc
++
Lc+
D0
What We can Learn from P50…
• Production Cross Section Not only for feasibility but also…
– Production Mechanism (Hosaka-san)• Does the Regge model work? (large s & small |t|)
– Coupling Constant/Form Factor -> LQCD?• What does the state population tell us?
– Spin/Isospin Structure– Wave Functions (Q-Diq picture or others)– So-called rho-mode (di-quark) excitation?
– Application of pQCD (Kawamura-san)• Applicable at large s &|t| (Hard process)?• Prediction from pQCD• Are there any feedback from the P50 measurement?
What We can Learn from P50…
• Expected Spectrum– Excitation Energy and Width
• Baryon Structure • Can we see a Quark-diquark picture?
• Decay Property– Decay branch/partial width
• Baryon Structure– G(Yc* -> pD)/G(Yc* -> pSc) ?
– Angular Distribution• Spin/Parity
Charm production Cross Section
• No exp. data for the p(p-,D*-)Lc is available but σ<7nb at pp=13 GeV/c at BNL (1985)
Charm production Cross Section
• Photoprod. of LcD*barX on p at Eg=20 GeV.– s(LcDbarX ) =44±7+11
-8 nb– s(D-X)=29±5+7
-5 nb– s(D*-X)=12±2+3
-2 nb
s(LcD*barX ) ~ 18 nb
• This seems sizable.
Abe et al., PRD33, 1(1986)
D*
LC , Xp
g
Charm production Cross Section
• s(pN→J/ψX) = ( 1±0.6 ) nb and (3.1±0.6)nb at 16 GeV/c and 22 GeV/c.– OZI-suppressed process!
J/ψ
XN
p
LeBritton et al., PLB81, 401(1979)
Comparison in strange sector
• OZI-suppressed process in Strange Sector– s(p-p→fn) = ( 1.66±0.32 ) nb at 4 GeV/c.
– s(p+p→fp+p) = ( 9.5±2.0 ) nb at 3.75 GeV/c
-> s(pN→fN)/s(pN→fX)~1/10? • OZI-non-suppressed process
– s(p-p→K*L) = ( 53±2 ) nb at 4.5 GeV/c
-> s(p-p→K*L)/s(pN→fX)~2? -> ??? s(p-p→D*Lc)/s(pN→J/yX)~2?
Crennell et al., PRD6, 1220(1972)
Avres et al., PRL32, 1463(1973)
Gidal et al., PRD17, 1256(1978)
Comparison in strange sector
1 10 1000.1
1
10
100
1000pi-p->K0Lambdapi-p->K0Sigma0pi-p -> K*0Lambdapi-p->K*0Sigma0pi-p -> K0Lambda(1405)pi-p -> K0Lambda(1520)pi-p->fnSeries23
s/s0
s(mb
)
s s∝ -a
Theoretical Estimations
• t-channel PS meson exchange • Comment on the pQCD model• Regge Model: revisit
Revisit the Regge Theory• shows the typical s-dependence of binary reaction cross sections at the large
s region;
– Regge trajectory: – scale parameter s0 : s at the threshold energy of the reaction AB → CD
(*In Kaidalov’s Model: s02(aD*(0)-1) =sCD
ar(0)-1 *sCDaJ/y(0)-1
sAB=(Σmi)A*(Σmj’)B, mi:transversal masses of the consituent quark)
• Treatment of G(-a(t)) to avoid possible singularities– Actually introduce phenomenological form factor
• G(-a(t)) → G(-a(t0)): naïve Regge• → G(1-a(t0)) : Kaidalov’s Regge [Z. Phys. C12, 63(1982)]• → exp(R2t): Grishina’s Regge [EPJ A25, 141(2005)]
2
2)(641 iTfpsdt
dcmpp
s
][)0()( TtTt --- gaa
)(021 )/))((( tsstggiTf aa-G
discussed with A. Hosaka
Regge Theory• PS(K,D)-Regge (Top): s/c-prod: ~10-5(Naïve), ~3x10-5(Kaidalov)• V(K*,D*)-Regge (Bottom): s/c-prod.: ~10-4(Naïve), ~3x10-5(Kaidalov)
calculated by A. Hosaka
a(0) g T1/2
(GeV)
K -0.151 3.65 2.96
D -1.611 3.65 4.16
K* -0.414 3.65 2.58
D* -1.020 3.65 3.91s/s0
s (a
rb.)
s (a
rb.)
s/s0
s/s0s/s0
s0(GeV2)
Naïve K*LK*Lc
4.0218.46
Kaidalov K*LK*Lc
1.664.75
Regge Trajectory
Scale Parameter
pp=20 GeV/c
pp=20 GeV/c
pp=20 GeV/c
pp=20 GeV/c
Regge Theory• Normalization with s(p(p-,K*)L) data [PR163, 1377(1967), PRD6, 1220(1972)]
– Naïve Regge shows a steeper s-dependence– Grishina’s Regge with R2=2.13 GeV-2 reproduces data well.
• Charm production: ~10-4 of strangeness production, → We expect s (p(p-,D*)Lc) close to 10 nb at pp=20 GeV/c.
1 101E-05
1E-04
1E-03
1E-02
1E-01
1E+00
1E+01
1E+02
1E+03
s/s0
s (m
b/sr
)
G(-a(t0))
exp(R2t)
G(-a(t0))
exp(R2t)
1 101E-06
1E-05
1E-04
1E-03
1E-02
G(-a(t0))
exp(R2t)
s(p(p- ,K
*)L
)/ s
(p(p
- ,D*)L
c)
s/s0
p(p-,K*)L
pp=20 GeV/c pp=20 GeV/c
p(p-,D*)Lc
Ratio of s- to c-prod.
Comment on the Coupling Constant
• Comparison of gD*D*p/gK*K*p and gLcND/gLNK*
– Estimated by means of the Light Cone QCD Sum Rule
– Exp. Data
• Taking gD*D*p/gK*K*p~1, gLcND*/gLNK*~0.67
→ We expect s (p(p-,D*)Lc) ~a few nb.
gK*K*p gD*D*p gD*D*p/gK*K*p
3.5* 4.5 1.3
gK*Kp gD*Dp gD*Dp/gK*Kp
4.5* 7.5 1.7
A. Khodjamirian et al.EJPA48, 31(2012)
gLNK* gLcND* gLcND*/gLNK*
-6.1+2.1-2.0 -5.8+2.1
-2.5 0.95+0.35-0.28
gLNK gLcND gLcND/gLNK
7.3+2.6-2.8 10.7+5.3
-4.3 1.47+0.58-0.44
gK*Kp gD*Dp gD*Dp/gK*Kp
~4.5 8.95+-0.15+-0.9 ~2+-0.2
M.E. Bracco et al.Prog. Part Nucl. Phys. 67, 1019(2012)
*note:g[Bracco]/2=g[Khodjamirian]
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• λ and ρ motions split known as isotope shiftsqsq, SO
Sc(1/2-,3/2-)
Λc(1/2-,1/2-
3/2-,3/2-, 5/2-)
Λc(1/2-,3/2-)
Σc(1/2-,1/2-
3/2-,3/2-, 5/2-)
Sc(1/2+,3/2+)
Λc(1/2+)
“Q” may isolate “qq”
q
Q
lq-q
Q
rq-q
λ mode
ρ mode
G.S.25
Hosaka-san
Excitation Energy Dependence• Production Rate in a quark-diquark model:
– D* exchange at a forward angle
– Radial integral of wave functions
Taking Harmonic Oscillator Wave Functions• I ~ (qeff/A)Lexp(-qeff
2/2A2), where A: oscillator parameter (0.4~0.45 GeV)
• For larger qeff, the relative rate of a higher L state to the GS increases as ~ (qeff/A)L
– Spectroscopic Factor: g • pick up good/bad diquark configuration in a proton • A residual “ud” diquark acts as a spectator
– Kinematic Factor w/ a propagator :
– Spin Dependent Coefficient, C:• Products of CG coefficients based on quark-diquark spin configuration• Characterized by the spin operator in the vector meson exchange,
u c“ud” “ud”
D*D*p f
g
Ycp
s
*De
BpIKCR 2||~ g
)]()exp()([2~ *3 rrqrrdI iefff
)/()12/|(|~ 2*
20* DBBD mqmpkkK --
p
discussed by A. Hosaka
g=1/2 for Lc’s =1/6 for Sc’s
massdiquak ":"
,//
udm
MmpMmpq
d
YdYpdpeff cc-
Estimated Relative Yieldpp=20 GeV/c
Lc1/2+
2286Sc
1/2+
2455Sc
3/2+
2520Lc
1/2-
2595Lc
3/2-
2625Sc
1/2-
2750Sc
3/2-
2820Sc
1/2-
2750Sc
3/2-
2820Sc
5/2-
2820Lc
5/2+
2880g 1/2 1/6 1/6 1/2 1/2 1/6 1/6 1/6 1/6 1/6 ½
C 1 1/9 8/9 1/3 2/3 1/27 2/27 2/27 56/135 2/5 3/5
K 0.86 0.95 0.94 0.85 0.85 0.92 0.91 0.92 0.91 0.91 0.83
qeff 1.33 1.43 1.44 1.37 1.38 1.49 1.50 1.49 1.50 1.50 1.41
R (Rel.) 1 0.03 0.20 1.17 2.26 0.03 0.06 0.07 0.33 0.31 1.55
• The estimation is valid for the D* exchange at a very forward angle.• The yields for some of Sc’s are suppressed due to g and C.
• The C coefficient is characterized by spin dependent interaction at the D*NYc vertex.
• Those for Lc’s are not suppressed very much at the excited states.• |I| reduces (increases!) an order of (qeff/A)L at higher L states.
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calculated by A. Hosaka
Estimated Relative Yield (strange sector)pp=4.5 GeV/c
L1/2+
1116S1/2+
1192S3/2+
1385L1/2-
1405L3/2-
1520g 1/2 1/6 1/6 1/2 1/2
C 1 1/9 8/9 1/3 2/3
K 1.02 1.23 1.17 0.99 0.97
qeff 0.29 0.31 0.38 0.36 0.40
R (rel.) 1 0.05 0.29 0.09 0.17Exp(mb/sr) 318+-12 186+-28 29+-6 32+-7 60+-13
• The yield for S1/2+ is suppressed due to g and C.• The estimation is not very far from the experimental data but for S’s.
• This already suggests a necessary modification of the model.• The measurement in charm sector provides valuable information
on the reaction mechanism and structure of baryons.
Exp.: p(p-,K0)Y, D.J. Crennell et al., PRD6, 1220(1972)
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calculated by A. Hosaka
Production Rate
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BpIKCR 2||~ g
)2exp(~ 22 A/(-q/A)qI effL
effL
LeffLL /A)qII (~/ 0
cAqI effLMAX
L GeV/ 0.6~2at 2~
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0 1 2 3 4 5
-0.4
-0.2
-1.11022302462516E-16
0.2
0.4
0.6
0.8
1
r*wf^p_s1/2(r)r*wf^Lc_s1/2+(r)j_0(qr), q=1.33
0 1 2 3 4 5
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
r*wf^p_s1/2(r)r*wf^Lc_p1/2-(r)j_1(qr), q=1.37
0 1 2 3 4 5
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1r*wf^p_s1/2(r)r*wf^Ls_s1/2+(r)j_0(qr), q=0.29
0 1 2 3 4 5
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1r*wf^p_s1/2(r)r*wf^Ls_p3/2-(r)j_1(qr), q=0.27
Lc(1/2+) Lc(1/2-)
L(1/2+) L(1/2-)
qeff=1.33 GeV/c qeff=1.37 GeV/c
qeff=0.29 GeV/c qeff=0.27 GeV/c
L=0
r {fm} r {fm}
r {fm} r {fm}
L=1
charm
strange
Summary…• Experimental Design
– 1000 count/nb/100d– Background reduction
• Signal Sensitivity: 0.1~0.2 nb for G~100 MeV state• 1 Decay particle detection inprove S/N very much
– Improve the acceptance Decay particle Acceptance• Production Rate
– A few nb for Lc production seems a plausible estimation
• Excitation Energy Dependence– The production rate is kept even at higher L states, depending on spin/isospin
structures of baryons.– How are the rho-mode states excited?
• How can we extract “diquark” in baryons • Can we can learn characteristic baryon structures from
– Excitation Energy Spectrum – Population (Production Rate)– Decay (Partial) Width/Branching Ratio– Angular Correlation– What is similarity to/difference from strange baryons 31
Structure and Decay Partial Width
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qqQ
qqq
Excited (qq) Good [qq]• L(1520) -> NK (D wave!)>πS , similarly L(1820), L(2100)• Possible explanation of narrow widths of Charmed Baryons
Illustrated by Hosaka
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Possible Subjects
• Charmed Baryon Spectroscopy• N*, Y* resonances via (p,ρ), (p,K*)• h’, w, f, J/y , D, D* productions off N/A• “K-K-pp” strongly interacting hadronic system• S=-1, -2, -3 baryon spectroscopy w/ K beam• others
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