Charmed Baryon Production(Charmed baryon Spectroscopy via p(p-,D*-)Yc)

11 Sep., 2013

H. NoumiRCNP, Osaka University

1

2

What are good building blocks of Hadrons?

Constituent Quarkq

qq

�͞ q

q

Diquark?[qq]

q(Colored cluster)

hadron (colorless cluster)q

qq

�͞ q

q

How to form baryons?

3

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

4

Q

qq

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)

5

HydrogenTarget

p-

K+

p-

20 GeV/c p- Beam

DispersiveFocal Plane

High-resolution, High-momentumBeam Line D*- Spectrometer

- p*D

*cY

-

-K

Missing Mass Spectrum

Missing Mass Spectroscopy

Measure D*-

Charmed Baryon Spectroscopy (P50)

Charmed baryon spectrometerModified design

FM cyclotron magnet

J-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 magnet

ps-

K+SSD

Fiber tracker

Beam GC

Internal TOF

Internal TOF

DCTOF 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)

Sum

Main 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 cos q > -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(m

b)

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)(64

1iTf

psdt

dcm

][)0()( TtTt

)(021 )/))((( tsstggiTf

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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25

• λ and ρ motions split known as isotope shiftsqsq, SO

Σc(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-)

Σc(1/2+,3/2+)

Λc(1/2+)

“Q” may isolate “qq”

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

*De

BpIKCR 2||~

)]()exp()([2~ *3 rrqrrdI iefff

)/()12/|(|~ 2*

20* DBBD mqmpkkK

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.27

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 0.17

Exp(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)

28

calculated by A. Hosaka

Production Rate

29

BpIKCR 2||~

)2exp(~ 22 A/(-q/A)qI effL

effL

LeffLL /A)qII (~/ 0

cAqI effLMAX

L GeV/ 0.6~2at 2~

30

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

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Structure and Decay Partial Width

32

qq

qqQ

qqq

Qq

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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