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J. Schümann National Taiwan University (Belle Collaboration)

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1 J. Schümann National Taiwan University (Belle Collaboration)
Baryonic B decays J. Schümann National Taiwan University (Belle Collaboration) Outline: Introduction B+ K+ Threshold enhancement Pentaquark search B+ p   Charmed baryonic modes Two body decays Conclusion Moriond QCD '05 Moriond QCD ‘05

2 The KEKB-factory Tsukuba Interaction Point 3Km Υ(4S) (10.58GeV/c2)
Electron 8 GeV Positron3.5 GeV 3Km Υ(4S) (10.58GeV/c2)  = 0.425 J.Schümann, ’05 Moriond QCD '05

3 Accumulated Data Lpeak = 15.16 nb-1s-1 Lday  1 fb-1 Ltot = 377 fb-1
J.Schümann, ’05 Moriond QCD '05

4 Belle Detector Aerogel Cherenkov Cnt. n=1.015~1.030
KLM  / KL detection 14/15 lyr. RPC+Fe TOF counter ECL CsI(Tl) SC solenoid 1.5T Silicon Vertex Detector Central Drift Chamber small cell +He/C2H6 8 GeV e- 3.5 GeV e+ Extreme Forward Calorimeter J.Schümann, ’05 Moriond QCD '05

5 Introduction B(2 body) < B(3 body) < B(4 body)
Baryonic decays: a unique and well-established feature of B meson decay (but not charm decay) B(2 body) < B(3 body) < B(4 body) Threshold enhancement in the invariant mass of the baryon-antibaryon system for 3-body BKBB decays Angular distributions discriminate between decay mechanisms, e.g. two-body decays and fragmentation Can search for exotic states in 3-body and 4-body decays J.Schümann, ’05 Moriond QCD '05

6 B+ΛΛK+ 140fb-1 First observation of bs s s decay
g b s s threshold peaking First observation of bs s s decay Signal Yield in 2D fit: 19.9 Efficiency: 4.0%-6.9% Statistical Significance: 7.4σ B : (  0.38) x 10-6 First Charmless B decay with two Λ! Threshold enhancement. Complements BφK(*) (bsss penguin) PRL 93, J.Schümann, ’05 Moriond QCD '05

7 Search for B+ΛΛπ+ 140fb-1 B (B+ΛΛπ+)<2.8x10-6 Result
b u Result Number of Background: ±1.0 Number of Observed events： 41 Number of Signal UL: < 21.7 No significant signal found 90% confidence-level upper-limit: B (B+ΛΛπ+)<2.8x10-6 Compare with Bppπ buud transition with ss popping PRL 93, J.Schümann, ’05 Moriond QCD '05

8 Improved B+ppK+measurement
140fb-1 b s Improved B+ppK+measurement threshold peaking Signal Yield in 2D fit: Efficiency: 28.3%-35.2% with Mpp<2.85 GeV/c2 B(Belle): (  0.50) x ( x PRL92, , 2004) B(Belle): (  0.58) x 10-6 , full range (charm veto for Mpp) B(BABAR): (6.7  0.9  0.6) x (81 fb-1, hep-ex/ ) J.Schümann, ’05 Moriond QCD '05

9 Chun-Khiang Chua, Wei-Shu Hou and Shang-Yuu Tsai(PLB544,2002)
Angular distribution: ppK+ & glueball search p K+ Өp X ppK signal Angular- Asymmetry: at pp rest frame N+-N- bs dominant process Fragmentation picture A = N++N- +0.08 - 0.07 s u = 0.59 s u u u d u u d K+ p p Proton against K- (p against K+) : flavor dependence! Possible Hints and Search for Glueball Production in Charmless Rare B Decays Chun-Khiang Chua, Wei-Shu Hou and Shang-Yuu Tsai(PLB544,2002) No significant signal: B (B+ glueball K+) x B ( glueball  pp) < 4.1x10-7 J.Schümann, ’05 Moriond QCD '05

10 Improved B0ppKs measurement
140fb-1 b s Improved B0ppKs measurement threshold peaking Signal Yield in 2D fit: 28.6 Efficiency: 15.4%-21.0% with Mpp<2.85 GeV/c2 B : (  0.12) x ( 0.78 x PRL92, , 2004) B : (1.20  0.14) x 10-6 (full range, charm veto) J.Schümann, ’05 Moriond QCD '05

11 Pentaquark search in BppKs, ppK+
Θ+(1540) : uudds (Belle) Θ+  K+ n Θ+  K0 p B0  Θ+ p B0  ppK0, B  ppKs Search for B signal with a 20 MeV pKs mass window cut at 1540MeV, the nominal mass of the pentaquark Θ++(1540) : uuuds (Belle,BABAR) B0  Θ++ p Θ++  K+ p u d p s K0 Θ+ d u s Θ+ K+ n J.Schümann, ’05 Moriond QCD '05

12 Pentaquark search in ppKs/K+
++: BABAR : 81 fb-1 +: Belle : 140 fb-1 Fixed background shape from sideband data Count the events in signal region and compare with background estimation Upper limit B(B0+p)x B(+pK0s)< 2.3x10-7 at 90% C.L. ++: Belle: B < 9.1 x 10-8 J.Schümann, ’05 Moriond QCD '05

13 Improved B0pΛπ- measurement
140fb-1 b s Improved B0pΛπ- measurement threshold peaking Signal Yield in 2D fit: 48.8 Efficiency: 10.4%-12.6% B: (  0.31) x (Mpp < 2.85 GeV/c2) B: (  0.39) x (full range) (3.97 x PRL90, , 2003) J.Schümann, ’05 Moriond QCD '05

14 Angular distribution: pΛπ-
X Λ p π- Өp X at pπ- rest frame at pΛ rest frame Fragmentation picture J.Schümann, ’05 Moriond QCD '05

15 B+pΛγ 140fb-1 First observation! Theoretical prediction:
bsγ MC pΛγSignal threshold peaking First observation! Simultaneous fit on BpΛγ & BpΣ0γ Signal Yield for BpΛγ with MpΛ<2.4GeV/c2: 34.1 Statistical Significance: 8.6σ B(BpΛγ ): (  0.20) x10-6 B(BpΣ0γ):<3.3 x 10-6 Theoretical prediction: *Pole Model: Phys.Lett. B533 (2002) B(B pΛγ ) ~ 1.2x10-6 B(B pΣ0γ) ~ 2.9x10-9 *QCD counting rules: (hep-ph/ ) B(B pΛγ ) ~ ( )x10-7 B(B pΣ0γ) ~ ( )x10-7 J.Schümann, ’05 Moriond QCD '05

16 B-  LC+ p p - 140fb-1 B x 10-5 Observation of a new 2-body decay
b c u d B-  LC+ p p - 264±20 signals B x 10-5 B-Lc+pp - 18.1s 20.1±1.5 ±2.0±5.2 B-Sc02455 p 8.4s ±0.36 ±0.95 B-Sc02520 p 2.9s ±0.12 ±0.33 +0.74 - 0.66 +0.56 - 0.49 + 6.6 - 5.9 SC(2455)0 32.6 + 5.7 - 5.0 SC(2520)0 12.8 Observation of a new 2-body decay sideband ~ 25% of the total Bcp- BF J.Schümann, ’05 Moriond QCD '05

17 B-  LC+ p p- - M(Lc+p) structure (Lc+p) mass (LC+p) SC0(LC+p-)
Low mass structure 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 +0.01 -0.02 +0.04 -0.03 M =  0.02 GBW = ±0.04 SC0(LC+p-) +0.77 - 0.72 B = (  0.43  1.01 ) x J.Schümann, ’05 Moriond QCD '05

18 B-  LC+ p p - Helicity distribution MC J c2 /nd Solid line : 0 0.97
Helicity angle Lc+ MC J c2 /nd Solid line : Dashed line : Q in B - at rest (Lc+p) direc. p data: dots MC : histograms Angular-Asymmetry: |N+-N-| A = = 0.32  0.14 N++N- M(Lc+p) <3.6GeV/c2 ( by DE fit for each mass bin ) J.Schümann, ’05 Moriond QCD '05

19 B0 LL, Lp, pp and other 140fb-1 90% confidence level UL:
B0  pp: 4.1 x 10-7 B0  Lp: 4.9 x 10-7 B0  LL: 6.9 x 10-7 Belle: B+  J/pL: 4.1 x 10-5 BABAR: B+  J/pL: 2.6 x 10-5 B+  J/pp: 1.9 x 10-5 Belle, 78fb-1 BABAR, 81fb-1 J.Schümann, ’05 Moriond QCD '05

20 Conclusion First b → sss hyperonic decay found
First b → s γ baryonic decay found The threshold enhancement in the baryon-antibaryon pair for 3-body Bbaryon decayse supports the fragmentation picture Intriguing structure found in the cp mass for Bcp- decays No hints for pentaquarks and glueballs yet Keep searching for all kinds of baryonic decay channels, possible pentaquarks, glueballs and especially direct CP violation with increasing statistics J.Schümann, ’05 Moriond QCD '05

21 Photon energy and Angular distribution
Λ γ p θx Fit results in bins of cosθX with Mp<4.0GeV/c2 (Assuming XpΛ, calculated in X rest frame.) bsγ MC qq background Signal Yield Signal Yield Lab frame J.Schümann, ’05 Moriond QCD '05

22 Preliminary M(Lc+p) structure in 3, 4 body decays B-  (Lc+p) p-
MC phase space, consistent with 4-body fine structures ? B0  (Lc+p) p+ p- B Signals by DE fit MC 4-body phase space SC++/0 (2455/2520) excluded J.Schümann, ’05 Moriond QCD '05

23 B0  LC+ p p - p - 140fb-1 Intermediate 3-body decays B0  Lc+ p p+ p-
Sc++(2455) Sc0(2455) 41.0±8.0 35.2±7.8 M(Lc+p +)+c.c. Sc++(2520) Sc0(2520) M(Lc+p -)+c.c. 58±14 19±11 (*1) total BF M(Lc+p ) B0  Lc p p+ p- 10.3±0.9 ±1.2 ±2.7(*1) B0  Sc p p- 8.0s 1.15±0.22 ±0.14 ±0.30 B0  Sc p p+ 8.3s 0.97±0.21 ±0.12 ±0.25 B0  Sc p p- 5.3s 1.04±0.234±0.12 ±0.27 B0  Sc p p+ 3.3s 0.33±0.19 ±0.054±0.09 J.Schümann, ’05 Moriond QCD '05

24 Chun-Khiang Chua, Wei-Shu Hou and Shang-Yuu Tsai(PLB544,2002)
Glueball Search Possible Hints and Search for Glueball Production in Charmless Rare B Decays Chun-Khiang Chua, Wei-Shu Hou and Shang-Yuu Tsai(PLB544,2002) Scanning through the mass region from 2.2 to 2.4 GeV region No significant signal 90% confidence-level upper limit: BF(B+ glueball K+) x BF( glueball  pp) < 4.1x10-7 J.Schümann, ’05 Moriond QCD '05

25 Particle Selection We use the PID (ACC+CDC+TOF) system to identify the charged particles. Proton: Kaon: Pion: Λ: reconstructed from Λpπ- TO p K π (p) (K) ~9% ~10% (π) ~4% ~8% From Fake rate J.Schümann, ’05 Moriond QCD '05

26 B Signal Reconstruction
In Υ(4S) rest frame: B Υ(4S) e- e- e+ e+ B Mbc 2D scatter plot 1D projection plot J.Schümann, ’05 Moriond QCD '05

27 Background suppression
The main background for B0pΛπ- and B+ΛΛπ+ is continuum qq events. (q=u,d,s,c). The Topology of continuum events and B decays are different. We choose |cosθThrust| S⊥ R2so R4so R2oo R3oo R4oo as the fisher input and combine it with cosθB to calculate the likelihood ratio. We define the Super-fox wolfram moment (F) like: We use Fisher’s discriminant to optimize the coefficients. B decay continuum events Υ(4S) J.Schümann, ’05 Moriond QCD '05

28 Background Suppression
SFW Moment (F) Likelihood Ratio (LR) uds off Data sideband charm Signal MC uds charm cosθB distribution uds off Data sideband charm off Data sideband Optimized by study J.Schümann, ’05 Moriond QCD '05

29 Signal Extraction PDFs:
Mbc PDFs: Background modeling: a line (curve) to represent the ∆E and the following parametrization first suggested by ARGUS group to represent the Mbc. Signal modeling: a double Gaussian for ∆E and a Gaussian for Mbc. 1D-binned fit: maximum Likelihood fit Branching fraction are calculated by ∆E fit Mbc fit for cross-check. 2D-unbinned fit (∆E-Mbc): Extended maximum likelihood fit. ∆E Mbc J.Schümann, ’05 Moriond QCD '05

30 Angular distribution: ppK+
Background yield of ppK+ J/ψK+ (J/ψpp) Consistent with qq background process No fragmentation signature in J/ψK+ J.Schümann, ’05 Moriond QCD '05

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