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Production rate s of Strange and Charmed baryons at Belle. Nuclear physics consortium . string. @  s = 10.52 GeV. Production rate of hadrons. Production rate s/s had /(2J+1)  exp (- a m h ) due to linear potential. Slope of meson (qq bar ) is different from baryons (qqq).

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production rate s of strange and charmed baryons at belle

Production rates of Strange and Charmed baryons at Belle

Nuclear physics consortium

string

@s = 10.52 GeV

production rate of hadrons
Production rateof hadrons

Production rates/shad/(2J+1) exp(-amh) due to linear potential

Slope of meson (qqbar) is different from baryons (qqq).

Slope depends on quark counting

“4 or 5-quark state” do not lie on “3-quark state”?

L(1405),pentaquark, Q+?

s/shad/(2J+1)

mh(mass of hadrons)[GeV]

previous data
Previous data

L(g.s.)/L(1520) deviate in LEP

good di-quark > bad di-quark?

L(1520)[3/2-] deviates in ARGUS

 [3/2-] state is special?

 L=0 ≠ L=1 ?

 L(1520) [3/2-] Lc*(2625)[3/2-]

L(1405) [1/2-] Lc*(2595)[1/2-]

LEP

s=92 GeV

R.L.Jaffe, Phys.Rept.409:1-45,2005

ARGUS

s=10.5 GeV

s/shad/(2J+1)

  • Error bar in ARGUS is large
  • More precise data
  • No series of charmed baryon
  • First systematic measurement
  • of production rate for charmed
  • baryons.

deviate

Belle

Mass of baryons (GeV)

slide4

Diquark picture

q

  • Interaction between quarks
  • Diquark correlations

q

Strange baryons

(L[uds], S[uds])

mu, md ≈ ms(qqq) uniform

q

q q

  • Charmed baryon
  • (Lc[udc], Sc[udc])
  • Diquark correlation is enhanced by weak Color Magnetic Interaction with a heavy quark
  • mu,md << mc diquark + quark
  • (qq) (Q)
  • qq ( ) S=0 “good” diquark
  • qq ( ) S=1 “bad” diquark

Q

strange baryon c harmed baryon
Strange baryon & Charmed baryon

Strange baryons

Charmed baryons

L, S

Lc, Sc

diquark + Quark

[qq] [c]

[qqs] uniform

S=0

S=1

S=1

S=0

u

u

ud

d

ud

d

L

L

s

s

c

c

L S

Lc>Sc

good di-quark > bad di-quark

due to strong attractive force of good diquark

slide6

In this work

Systematic study of baryons

to search for “exotic” baryons in strange and charmed baryons.

Information on diquark picture of charmed baryons

in contrast with strange baryons.

L, S, S*, X, W, Lc, Lc* ,Sc ,Sc*

First systematic measurement for series of charmed baryons.

It is interesting and important to look at the tendency

of many baryons by precise measurement.

Belle data, well constructed detectors and good statistics.

slide7

Data of Belle

Aerogel Cerenkov

Time Of Flight

CsI calorimeter

S.C. solenoid

1.5T

3.5GeV e+

8GeV e-

Central Drift Chamber

Silicon Vertex Detector

KL μ system

Integrated luminosity 79.366 fb-1 @s = 10.52 GeV

702.623 fb-1 @ s = 10.58 GeVϒ(4S)

good vertex reconstruction
Good vertex reconstruction

Profile of interaction point (IP)

SSD placed in 3cm/2cm from Interaction point (IP), and low materials.

Resolution of reconstructed vertex for B J/Psi Ks is about 80 mm.

Good for hyperon (long life) reconstruction.

hyperon reconstruction

momentum

vectorof L

Hyperon reconstruction

p-

  • Decay processes
  • X-  Lp-
  • W-  LK-
  • Wc0  W-p+
  • Decay processes
  • L  p p-
  • S0  Lg
  • S*(1385)+  Lp+

p

IP

Interaction point

p

p-

Dx

L

ct = 7.89cm

ct=7.89cm

X-/W-

ct= 4.91cm

/ 2.64cm

p-

IP

p+or g

(S0) (S*+)

p+ for Wc0

slide10
L

ds/dxp

L / Lbar

preliminary

Mass spectrum of L

Xp

Scaled momentum, xp = pc.m. /

pc.m. : momentum of baryons

s : beam total energy

M : mass of baryons

“Inclusive” total cross section

Feed down processes from higher states

L + Lbar = 373.9 ± 0.5 pb

mass spectra
Mass spectra

S0(1192)  Lg(BR~100%)S*(1383)+Lp+(BR=87%)

real data events in 0.3 < xp <0.4

real data events in 0.3 < xp <0.4

inclusive cross sections vs x p
“Inclusive” cross sections vs. xp

S0 +c.c. S*+ +c.c.

ds/dxp

ds/dxp

preliminary

Xp

Xp

Inclusive total cross section

Inclusive total cross section

S0 + S0 = 97.0 ± 1.5 pb

S* + S* = 33.2 ± 2.4 pb

direct cross section of l
direct cross section of L
  • feed-down were subtracted from inclusive cross sections.
  • Isospin symmetry was assumed for S* and X production cross-sections.

Result

(inclusive)

-23.6 8.0pb

direct s 0 and s production
direct S0 and S*+ production
  • feed-down were subtracted from inclusive cross sections.
  • Isospin symmetry was assumed for S* and X production cross-sections.

Result

S*+ + c.c. (direct) : 33.2 ± 2.4 pbS*+ + c.c. (inclusive)

- 0.4 ± 0.06 pbL(1520) + c.c.

= 32.8 ± 2.4 pb

l 1520
L(1520)

Select p and K- from IP with cuts for

distance from IP

○○(4S) data

▽▽Continuum data

Y / anti-Y

Mass spectrum of L(1520)

preliminary

L(1520)pK-

BR=22.5%

direct cross section l 1520
Direct cross section L(1520)

L(1520)+c.c. (direct) = 15.3 ± 0.5 pb inclusive

– 0.34 ± 0.17 pb Lc+

= 15.0 ± 0.26 pb

cross sections of x and w
Cross sections ofX andW

X / X

W / W

●●@10.58, (4S) data

○○ @10.52, Continuum data

Y / anti-Y

preliminary

X + Xbar

inclusive cross section = 25.55 +- 0.64 pb

W + Wbar

inclusive cross section = 1.15 +- 0.32 pb

w c w p c c
Wc  W-p+ +c.c.

Counts

Event rate / Lint.

preliminary

xp

Mass [GeV]

BR 1.25±0.5% for W-X

0.25±0.12% for W-p+

by phenomenological calculation (ref. PDG)

s x BR (W-p+) + c.c. = 0.04 0.003 pb

Wc  W-X = 0.2 pb

l c l c s c 0 and s c 0
Lc+, Lc*+,Sc0, and Sc*0
  • Decay process analyzed in this work
  • Lc+  pK-p+
  • Lc*(2625) Lc+p+p-
  • Sc0  Lc+ p-
  • Sc*(2520)  Lc+ p-

+c.c.

Mass spectrum ofpKp

Lc+

Mass plot

slide21

Lc+(2625)

○○(4S) data

▽▽Continuum data

Y / anti-Y

Mass spectrum

preliminary

ds/dxp(nb)

Lc+(2625)

Lc(2625)+

Lc(2595)+

Xp

mass spectrum
Mass spectrum

Lc+ p- decay processes

Sc(2455)0

  • Exclude in analysis
  • Lc*(2595)+ Lc+p+ p-
  • Lc*(2625)+ Lc+p+ p-

Sc(2520)0

slide23

Cross sections

○○(4S) data

▽▽Continuum data

Y/ anti-Y

preliminary

preliminary

Sc0(2455)

Sc0(2520)

direct l c and s c production
direct Lc and Sc production
  • Lc+ + c.c. (direct)

= 189 ± 66 pb inclusive

- (17.9 ± 6.0 pb ) x 3 Sc0,+,++(2455) + c.c.

  • - (18.8 ± 6.4 pb) x 3 Sc0,+,++(2520) + c.c.
  • - (31.3 ± 10 pb) Lc+(2625) + c.c.
  • = 47.6 ± 16.2 pb
  • Sc0(2455) +c.c. (direct) = 17.9 ± 6.0 pb
  • Sc0(2520) + c.c. (direct) = 18.8 ± 6.4 pb
  • Lc+(2625) + c.c. (direct) = 31.3± 10 pb

Λc(2595) and Λc(2775)

feed down

are included.

result and discussion
Result and discussion
  • Mass dependence
  • strange ≠ charm
  • not lie on the same line
  • Large discrepancy to ARGUS
  • on L, and S*
  • treatment of feed down?
  • Deviation of L(1520)[3/2-]
  • is not clear.
  • W < L, S, X
  •  W[sss] with “ “
  • no good diquark

s/shad/(2J+1)

This work (very preliminary)

ARGUS

Previous Belle work

Mass of baryons (GeV)

slide26

Results and discussion

  • Charmed baryons do not lie on “one” line.
  • Jp : no measurement or not well measured
  • quark-model prediction
  • Lc > Sc
  •  good diquark > bad diquark
  • Large rate of Lc(2625)[3/2-](L=1 state)
    • Prefer [3/2-] or L=1? Why?
    • Rate of L(1520)[3/2-] is not large.
    • Rates of Lc(2595)[1/2-](L=1 state)
    • and L(1405)[1/2-] are “key”.
  • Wc : no measurement of BR
  • a plot with BR(0.24+-0.12%)
  • by the phenomenological calculation.
  • Production rate  BR

Charmed baryons

Lc(g.s)[1/2+]

s/shad/(2J+1)

Lc(2625)[3/2-]

Wc

Sc0(2455)[1/2+]

Sc0(2520)[3/2+]

Sc(2800)[??]

use 3/2

Very preliminary

Mass of baryons (GeV)

states
States
  • [1/2+]
  • L(1405) [1/2-]
  • L(1520) [3/2-]
  • S [1/2+]
  • S(1385) [3/2+]
  • X [1/2+]
  • X(1530) [3/2+]
  • W [3/2+]

Lc+[1/2+]

Lc(2595)+[1/2-]

Lc(2625)+ [3/2-]

Sc(2455) [1/2+]

Sc(2520) [3/2+]

Xc [1/2+]

Xc*

Wc [1/2+]

Wc*

On going

Unknown J, BR

slide28
M(Xp)

X(1530)

Xc

production rates
Production rates

s/shad/(2J+1)

Mass – Mass(g.s.) [GeV/c2]

summary
Summary
  • We measure production rates of strange and charmed baryons ats = 10.52 GeVat Belle.
  • “Systematic” study provides information on quark structure of hadrons.
  • Configuration and performance of Belle detector is good for long-life particles like L, X, and W.
  • We observed ‘charmed baryons do not lie on one line’.

Can we explain by a diquark picture?

  • Feed down processes
  • Further study of many baryons with various spin-parity

is interesting to see their quark structures.