1. Baryon Production and Pentaquark Searches at B Factories
B.Mellado (University of Wisconsin-Madison)
For the BaBar and Belle Collaborations
FPCP04, Daegu, Rep. of Korea 10/08/04

2. Outline Introduction Charmless B decays into baryons
Branching Fraction measurements
Searches for the + and ++ pentaquarks
Inclusive searches in e+e- for strange pentaquarks
B decays into Baryons involving charm
Search for charmed pentaquarks
Structure in M(c+p) spectrum
Studies of charmed Baryons (not covered)
Belle-CONF-0463, BaBar-CONF-04/04, BaBar-CONF-04/22
Outlook and Conclusions
Bruce Mellado, FPCP04 10/08/04

3. Baryon Production in B Decays
Little is understood in Baryon production in B decays
Significant input from data in recent years
A lot of progress due to B factories
BBaryons not saturated by BcX
Dominance of multi-body final states
Βr(B2body)<Βr(B3body)<Βr(B4body)
Baryon-Antibaryon enhancements? Exotic states?
Enhancements?
Exotic states? ?
Pentaquarks?
Bruce Mellado, FPCP04 10/08/04

4. Pentaquark Searches
Triggered by a prediction (Diakonov et al. Z.Phys. A359 (1997) ) narrow peak in K+n invariant mass was observed
M.Karliner Moriond04
Discovery of + (S=+1, uudds) has created a lot of excitement
NA49 gave evidence of -- (S=-2, dsdsu, GeV)
H1 gave evidence of charmed c0 (ududc, 3.1 GeV)
A number of experiments have reported negative results
Bruce Mellado, FPCP04 10/08/04

5. Pentaquark Searches (cont)
B-Factories is at (4S) threshold BB -
Continuum
Y (4S)
B factories are also produce copiously u d s c quarks
Additional production mechanisms in inclusive searches
Bruce Mellado, FPCP04 10/08/04

6. KEKB/Belle Performance
KEKB peak luminosity: 1.39 x A x 1.6A
253 fb-1 on Y(4S)
28 fb-1 below Y(4S)
281 fb-1
3.5 GeV e+
8 GeV e-
Bruce Mellado, FPCP04 10/08/04

7. PEP-II/BaBar Performance
PEP-II top luminosity: 9.2 x 1033cm-2s-1
221 fb-1 on Y(4S)
23 fb-1 below Y(4S)
244 fb-1
Run1
Run2
Run3
Run4
3.1 GeV e+
9 GeV e-
Bruce Mellado, FPCP04 10/08/04

8. B Signal Reconstruction
In Υ(4S) rest frame: ∆E B
Υ(4S) e- e- e+ e+ B
MES
Bruce Mellado, FPCP04 10/08/04

9. Searches for Strange pentaquarks
B Charmless Decays
Searches for Strange pentaquarks
Bruce Mellado, FPCP04 10/08/04

10. First Observation of B+ΛΛK+
First charmless B decay with ΛΛ with 7.4  significance
Probes the decay bsss
Complementary to BφK(*)
Threshold enhancement of ΛΛ
140 fb-1
Threshold enhancement
Phase Space MC
Bruce Mellado, FPCP04 10/08/04

11. Search for B+ΛΛ+ No evidence found with 140 fb-1
90% Confidence level set
# of background 37.51, # of observed events 41
PRL , 2004
Bruce Mellado, FPCP04 10/08/04

12. First Observation of B+pΛ
Preliminary
Simultaneous fit on B+pΛ and B+p0
Signal yield for BpΛ with MpΛ<2.4GeV: 34.1
140 fb-1
bs MC
pΛ Signal
Threshold enhancement
Bruce Mellado, FPCP04 10/08/04

13. Improved BF(B0ppKS) Measurement
Preliminary
Re-analysis with 140 fb-1 with signal yield with Mpp<2.85 GeV
Threshold enhancement in pp
PRL , 2004
Threshold enhancement
Phase Space MC
Bruce Mellado, FPCP04 10/08/04

14. Pentaquark + Search in B0ppKS
Preliminary
Search for a pKS resonance at ~1.54 GeV as observed in other experiments
Corresponds to + (S=+1) with ududs
Background shape from side-band data
1.53<M(pKS)<1.55 GeV
Negative Search
Bruce Mellado, FPCP04 10/08/04

15. Inclusive Pentaquark +pKS Search
Preliminary
123 fb-1
Clean peak for c+pKS (52K events) but no narrow structure at 1.54 GeV
Number of checks: stringent cuts on KS, require recoiling K- and/or anti-proton with all possible combinations. c+ visible but no pentaquark
Bruce Mellado, FPCP04 10/08/04

16. Inclusive Pentaquark +pKS Search (cont)
Preliminary
Developed model independent limit setting
Signal is extracted as a function of p* and corresponding 95% CL limit is calculated
95% CL UL BF< (363.1) fb for =1 (8) MeV
Bruce Mellado, FPCP04 10/08/04

17. Pentaquark +pKS Search Using K Interactions in the Detector Material
Use secondary pK pairs. Projectile has low energy, similar to most experiments, which observed +
(1520) yield is 15519±412 events
Mass consistent with PDG
No evidence of + found
155 fb-1
pKS
pK-
nothing
(1520)
17cm p K
Slide1
Bruce Mellado, FPCP04 10/08/04

18. Pentaquark +pKS Search K Using Interactions … (cont)
155 fb-1
Limit setting procedure
Assume + is narrow
Fit M(pKS) to resolution function (~2MeV)
Fix mass at different points and scan wide mass interval
Fit result for M(pKS) =1.54 GeV: N=29±65 events
Upper Limit: N<94 events at 90%CL (Feldman-Cousins method)
Yield
Slide1
ZEUS-1
CLAS+1
m, GeV
Search range
Bruce Mellado, FPCP04 10/08/04

19. Improved BF(B+ppK+) Measurement
Preliminary
Re-analysis with 140 fb-1 (Belle) and 89 fb-1 (BaBar)
Results on BF consistent with PRL (2004)
Threshold enhancement in pp
Mpp<2.85 GeV
Full Mpp Range
Belle
Side Band
Signal
Bruce Mellado, FPCP04 10/08/04

20. Search for ++pK+ in B+ppK+
Preliminary
Pentaquark *++pK+ (uuuds) predicted to lie in 1.43<M(pK+)<1.70 GeV
No evidence was found for *++pK+, 90% CL limits were set
Other experiments have also reported negative searches
1.6<M(pK+)<1.8 GeV
Belle
No background
With background
Bruce Mellado, FPCP04 10/08/04

21. Inclusive Search of Pentaquark 5---- and 50-+
123 fb-1
Preliminary
NA49 gave evidence of -- (S=+2, dsdsu, GeV)
Displaced Vertexes
Two displaced vertexes with loose particle ID
Select masses near nominal 0 and -
Control samples
(1530)*- and c(2470)0
Bruce Mellado, FPCP04 10/08/04

22. Inclusive Search of Pentaquark 5-… (cont)
(1530)*-
c(2470)0
Bruce Mellado, FPCP04 10/08/04

23. Charge conjugation is assumed
Preliminary
123 fb-1
Other inclusive searches for other pentaquarks were performed
5-, 50, N50, N5+ in the 0K and 0K modes
No evidence was found 5
Charge conjugation is assumed
Bruce Mellado, FPCP04 10/08/04

24. Preliminary
123 fb-1
Bruce Mellado, FPCP04 10/08/04

25. B Decays Involving Charm Searches for Charmed Pentaquarks
Bruce Mellado, FPCP04 10/08/04

26. B0D(*)-pp+ and B0 D(*)0pp
New Observation
Preliminary
112.5 fb-1
B0D*-pp+
130 ± 14
B0D-pp+
238 ± 22
B0D*0pp
13 ± 4
B0D0pp
96 ± 11
BaBar
CLEO
New Decay
Belle
Bruce Mellado, FPCP04 10/08/04

27. B0D(*)-pp+ and B0 D(*)0pp
Estimate compatibility of data to phase space MC with Kolmogorov-Smirnov test in the four B decays
Observe asymmetry between M(D0p) and M(D0p) in B0 D0pp decays.
K-S prob.=
B0 D0pp
K-S prob.=0.77
M(D0p)+cc
M(D0p)+cc MC
uduuc MC
uuduc
Bruce Mellado, FPCP04 10/08/04

28. M(D0p)/M(D0p) asymmetry in B0 D0pp
uduuc
112.5 fb-1
uuduc
Bruce Mellado, FPCP04 10/08/04

29. Search for Charmed Pentaquarks in B0D(*)-pp+ and B0 D0pp
39321
Preliminary
Look for c0 D(*)-p (ududc) and c*+ D0p (uuudc)
No evidence of charmed pentaquark with mass 3.1 GeV (H1)
90% CL limit setting H1
Slide1
Bruce Mellado, FPCP04 10/08/04

30. BF(B-c+p-) Measurement
Preliminary
140 fb-1
Observation of a new 2-body decay B-Sc02455 p
~25% of the BF
264±20
BF in units of 10-5
B-Lc+pp -
18.1
20.1±1.5 ±2.0±5.2
B-Sc02455 p
8.4 
3.67±0.36 ±0.95
B-Sc02520 p
2.9 
1.26±0.12 ±0.33
SC(2455)0
32.6
+ 6.6
- 5.9
+ 5.7
- 5.0
SC(2520)0
12.8
Bruce Mellado, FPCP04 10/08/04

31. M(c+p) structure in B-c+p-
Preliminary
140 fb-1
(Lc+p) mass
Low mass structure
(LC+p)
Phase space
function
B signals by DE fit for each mass bin
M(Lc+p -)>2.6 & M(pp-) >1.6GeV/c2
to remove Sc(2455/2520) & D(1232)
6.2 s significance
+0.02
-0.03
M = ±0.02 GeV
GBW = 0.09±0.04 ±0.04 GeV
+0.77
- 0.72
BF = ( ±0.43 ±1.01 ) x
SC0(LC+p-)
Bruce Mellado, FPCP04 10/08/04

32. M(c+p) structure in 3-4 Body Decays
Preliminary
140 fb-1
B-(c+p)-
Four body decay BF B0(c+p)+- improved
Is the 4-body decay consistent with phase space hypothesis?
B0(c+p)+-
Phase space MC
Bruce Mellado, FPCP04 10/08/04

33. Outlook and Conclusions
Wealth of data coming from the B factories on B decays involving Baryons
First observation of B+ΛΛK+ (bsss) and B+pΛ reported. Limit set on B+ΛΛ+ decay. Improve a number of BF measurements
First observation of B0D-pp+. Observe asymmetry between M(D0p) and M(D0p) in B0D0pp
Confirm dominance of multi-body final states and baryon-antibaryon threshold enhancements
Bruce Mellado, FPCP04 10/08/04

34. Outlook and Conclusions (cont)
Pentaquark searches in B factories so far negative
No evidence so far of strange (, 5, N5) and charmed (c) pentaquarks in both exclusive B decays and inclusive searches in e+e-
Evidence reported by Belle on M(c+p) structure in B-(c+p)- with 6.2 significance
M(c+p)3.3 GeV
BW=0.090.040.04 GeV
Bruce Mellado, FPCP04 10/08/04

35. Back-up Slides
Bruce Mellado, FPCP04 10/08/04

36. B0D(*)-pp+ and B0 D(*)0pp (cont)
Preliminary
112.5 fb-1
Pin down dynamics of B decay by looking into Dp & pp spectra
Observe asymmetry between M(D0p) and M(D0p) in B0 D(*)0pp decays
Probability that data is compatible with phase space MC
Bruce Mellado, FPCP04 10/08/04