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Baryonic B Meson DecaysBaryonic B Meson Decays
IntroductionCharmless decaysCharmful decays Summary
Min-Zu Wang (王名儒 )National Taiwan University
2007/1/9 CYCU Seminar
CP violation in Standard ModelCP violation in Standard Model
In 1973, M. Kobayashi and T. Maskawa realized: CP violation third generation of quarks
In SM, CPV can be accommodated via the CKM matrix, which relates quark mass eigenstates to weak eigenstates:
With 3 quark generations, there is 1 phase in the CKM matrix which is physical (can’t be absorbed in redefinition of the fields)
allows possibility of CP violation
b
s
d
VVV
VVV
VVV
b
s
d
tbtstd
cbcscd
ubusud
'
'
'qi
qj
W
Vij
2007/1/9 CYCU Seminar
Two B FactoriesTwo B FactoriesSLAC (史丹福大學 )
BaBar
KEK (日本 )
Belle
2007/1/9 CYCU Seminar
Integrated LuminosityIntegrated Luminosity
1.7
229M BB
2007/1/9 CYCU Seminar
B Meson ProductionB Meson Production
28.0hadr
bb
Electron-Positron collider: e+e- (4s) B0B0
Only 4s resonance can produce B meson pair Low B0 production cross-section: ~1 nb Clean environment, coherent B0B0 production
GeV28.5
GeV58.10)4(
B
S
M
M
2007/1/9 CYCU Seminar
udsuds
offoff Data sidebandData sideband
charmcharm
Background SuppressionBackground SuppressionSFW Moment (F)SFW Moment (F)
cosθB distributioncosθB distribution
udsuds
offoff Data sidebandData sideband
charmcharm
Signal MC
udsuds charmcharm
offoff Data sidebandData sideband
Likelihood Ratio (LR)Likelihood Ratio (LR)
bs
s
LL
LLR
Optimized by
studybs
s
2007/1/9 CYCU Seminar
Signal ExtractionSignal Extraction
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.
])/(1(exp[)/(1)( 22beambcbeambcbcbc EMEMMMf
N
iibcibibcis
BS EMBPEMSPeL1
)( )],(),([
1D-binned fit: maximum Likelihood fitBranching fraction are calculated by ∆E fit
Mbc fit for cross-check.
2D-unbinned fit (∆E-Mbc): Extended maximum likelihood fit.
∆E
∆E Mbc
Mbc
2007/1/9 CYCU Seminar
First Observation of Charmless Baryonic B Decays B+ ppK+
First Observation of Charmless Baryonic B Decays B+ ppK+
PRL 88, 181803 (2002)
BF(3-body) >> BF(2-body)
With charmonium veto
PRD 65091103(2002)
( )
2007/1/9 CYCU Seminar
New type of B Decays:New type of B Decays:
Peak at Low Mass
Possible explanations Baryon form factor? Quasi 2-body Decay? glueball baryonium Fragmentation?
KppB
fJ(2220)?
Phase-space MC
2007/1/9 CYCU Seminar
Observation of BObservation of B00→ P→ PΛπΛπ-- MpΛ PlotObservation of BObservation of B00→ P→ PΛπΛπ-- MpΛ Plot
Theoretical PretictionTheoretical PretictionTheoretical PretictionTheoretical Pretiction 78.1fb78.1fb-1 -1 DataData78.1fb78.1fb-1 -1 DataData
Search for BPΣ0π- negtiveSearch for BPΣ0π- negtive
PRL90 201802(2003)
2007/1/9 CYCU Seminar
Many rare baryonic decays foundMany rare baryonic decays found
Kpppp Kspp
*Kpp 0*Kpp
PRL92 131801(2004)
2007/1/9 CYCU Seminar
Threshold EnhancementThreshold Enhancement
PLB 617, 141-149, 2005
ppK+ ppK0S
p-
Glueball is ruled out
2007/1/9 CYCU Seminar
Angular distribution: ppK+
p
p
K+ӨpX
Proton against K- (p against K
+) : flavor dependence!
ppK signal
at pp rest frame
2007/1/9 CYCU Seminar
Information from the ppK+Dalitz plot Information from the ppK+Dalitz plot
•The lower bands shown in the plots are J/psi and eta_c.
•Asymmetry near threshold of ppbar indicates flavor dependence
•Anti-proton moves slower in parallel with proton
PRD72 051101 (2005)
2007/1/9 CYCU Seminar
dominant decay diagram
Decay diagrams of Decay diagrams of J/ΨJ/Ψ to baryon pair to baryon pair
042.0036.0676.0 Latest BES result :
θαθd
dN 2cos1cos
< λ1 λ2|U|JM> = AJ λ1 λ2 links DJM λ1- λ2 (θ,φ)
Massless
Proton mass + E M
Quark mass
Kada, Marco and Parisi
Quark + scaler diquark
2007/1/9 CYCU Seminar
A twist to compare A twist to compare αA twist to compare A twist to compare α
General form of α: (Phys. Rev. D 51, 3487–3500)
11
11
10 1
2
042.0036.0676.0: BES
10
11~ - 0.8
11
2007/1/9 CYCU Seminar
Fit cosθ ( J/Fit cosθ ( J/ → p p) → p p)Fit cosθ ( J/Fit cosθ ( J/ → p p) → p p)
Likelihood fit
B= -0.60 ± 0.13 (stat) ± 0.14 (syst)
pp
= 0.43 ± 0.13 (stat) ± 0.14 (syst)
L = e-(Ns+Nb)/N! [NsPs(Mbci , Ei)(cos)P(cos)+NbPb(Mbci , Ei)]
(cos) - normalized efficiency, P(cos) =
(1+cos2)/(2+2/3)
signal
χ2 fit
2007/1/9 CYCU Seminar
Pentaquark search in ppKsPentaquark search in ppKs
Θ+(1540) : uuddsΘ+ K+n Θ+ K0 p
B0 Θ+ pB0 ppK0, B ppKsSearch for B signal with a 20 MeV pKs mass window cut at 1540MeV
dduu s
Θ+ K+ n
d du
uud
p
ds
K0
Θ+
uudsd
2007/1/9 CYCU Seminar
Pentaquark search in ppKsPentaquark search in ppKs
Fixed background shape from sideband data
Count the events in signal region and compare with background estimation
BF product upper limit < 2.3 x10-7 at 90% C.L.
2007/1/9 CYCU Seminar
B+pΛγ (b sγ) B+pΛγ (b sγ)
PRL 95, 061802, 2005Simultaneous fit on BpΛγ and BpΣ0γSignal Yield for BpΛγ with MpΛ<2.4GeV/c2: 34.1
Statistical Significance: 8.6σ
BF(BpΛγ )(2.16 ± 0.20)x10-6
BF(BpΣ0γ):<4.6 x 10-6
140fb-1
pΛγSignal
+7.1- 6.6
+0.58- 0.53
bsγ MC
Not bremstrahlung
2007/1/9 CYCU Seminar
Photon energy and Angular distributionPhoton energy and Angular distribution
Fit results in bins of cosθX with MpΛ<4.0GeV/c2
(Assuming XpΛ, calculated in X rest frame.) Λ
γ
p
θx
bsγ MCSignal Yield
qq backgroundSignal Yield
Lab frame X frame
2007/1/9 CYCU Seminar
ggb b s s
s s s s B+ΛΛK+B+ΛΛK+
PRL 93,211801, 2004PRL 93,211801, 2004
+6.5- 5.1
+0.90- 0.70
First observation of bs s s baryonic decay
Signal Yield in 2D fit: 19.9Efficiency: 4.0%-6.9%Statistical Significance: 7.4σ
BF:(2.91 ± 0.38) x 10-6
1.1. First Charmless B decay First Charmless B decay with two with two ΛΛ! !
2.2. Threshold enhancement Threshold enhancement again.again.
3.3. Compliment to BCompliment to BφφKK(*)(*)
(b(bsss penguin)sss penguin)
1.1. First Charmless B decay First Charmless B decay with two with two ΛΛ! !
2.2. Threshold enhancement Threshold enhancement again.again.
3.3. Compliment to BCompliment to BφφKK(*)(*)
(b(bsss penguin)sss penguin)
140fb-1
threshold peaking
2007/1/9 CYCU Seminar
Observation of ηηcc Λ Λ Λ Λ Observation of ηηcc Λ Λ Λ Λ
new
Ratio for baryon quark-diquark model check
PRL 97, 162003 (2006)
2007/1/9 CYCU Seminar
Result for B+ppπ+Result for B+ppπ+ 414fb-1
• Fit result for exp7-43 with Mpp<2.8GeV/c2
• Signal Yield for B+ppπ+ : 180.9• LR selection: 0.85 • Statistical Significance: 13.5σ• Signal region
+19.1-18.3
Mbc>5.27 GeV/c2 |ΔE|<0.05 GeV
ppK
ppπ
2007/1/9 CYCU Seminar
Theoretical PredictionsTheoretical Predictions
Angular distributionPerturbative QCD(PQCD):
(hep-ph/0606141)Final-State Interaction (FSI):
(hep-ph/0609133)
Upper limitBF of B+→pΔ++ was predicted to be
2.9×10-7 (QCD sum rules, Nucl. Phys. B 345, 137 (1990) )
3.2×10-4 (pole model, Phys. Rev. D 43, 1599 (1991); Phys. Lett. B 237, 513
(1990))
1.4×10-6 (pole model, Phys. Rev. D 66, 014020 (2002))
predicted curve
hep-ph/0606141
B+→ppK+
B+→ppπ+
fitting curve
2007/1/9 CYCU Seminar
Preliminary
We apply Mpπ<1.4 GeV/c2 for B+→pΔ0 and B+→pΔ++ study. B+→pΔ0 expected background:81.2background uncertainty:2.0%observed event:?upper-limit:? averaged efficiency:4.0±0.1%BF(B+→pΔ0)< ?B+→pΔ++ expected background:72.3background uncertainty:2.1%observed event:?upper-limit:?
averaged efficiency:11.6±0.2%BF(B+→pΔ++)< ?
Current Work: B+→ppπ+
414fb-1
B+→ppπ+
. signal region
. sideband region
B+→pΔ0
B+→pΔ++
2007/1/9 CYCU Seminar
Current Work:Current Work:
The studies of intermediate two-body decays:
We apply 2.262<MΛπ<2.310 GeV/c2 for B0Λcp.BF(B0Λc p): ?
BF(B0Λc p): (2.19 ±0.32 ±0.57) x10-5 (PRL 90 121802)
We apply Mpπ<1.40 GeV/c2 for B0ΛΔ0.BF(B0ΛΔ0 ) < ?
We apply 1.30<MΛπ<1.45 GeV/c2 for
B-Σ*0 p.BF(B0Σ*+ p) < ?
+0.56- 0.49
pB
2007/1/9 CYCU Seminar
Study of Study of 0 pB
Phase spacep Λπ0 Signal
Signal yield:Signal yield:
Signal Yield for BpΛπ0 with MpΛ<2.8GeV/c2: 56.1Statistical Significance: 10.2σBF(BpΛπ0 ):
Signal Yield
First observation!
2007/1/9 CYCU Seminar
Study of helicity selection rules in weak decay Study of helicity selection rules in weak decay
Decay parameter α:Transition rate R is proportional to (1+αcosθ).
θ is defined as the angle between the initial hyperon polarization and the momentum of the final baryon.
αΛ=0.642±0.013 (PDG, Journal of Phys. G33, 1 (2006))
The effective angular asymmetry parameter α :(J. Phys. G: Nucl. Part. Phys. 29(2003) B15-B22)
For the cascade decay BΛXπ-pX :
θpb is defined as the supplementary angle between the
emitted proton momentum and the B momentum in the Λ rest frame.
π-
p
Λ
θω
π-B
θpb
p
2007/1/9 CYCU Seminar
Measurement of α inΛdecaysMeasurement of α inΛdecays
Paper J.Phys. G29, 15 (2003) reported that the dΓ/d cosθ is proportion to (1+αcosθ) when the s quark comes from bLsL penguin-type transition.Systematic error
Source PID LR Fitting Results
B-pΛγ 0.01 0.01 0.01
B-pΛπ0 0.01 0.01 0.01
B0pΛπ- 0.01 0.01 0.01
2007/1/9 CYCU Seminar
B0 D(*)0 p p
D0 K- +
D0 K- + - +
D0 K- +
BB00 D D00pppp BB00 D D0* 0* pppp
Belle: PRL 8989, 151802 (2002) 29.4 fb-1
b b c c u u
d d
33.6evnts
24.2evnts
34.2evnts
8.9
5.6
5.1
total 19.3 evnts 5.6
D*0 D00
2007/1/9 CYCU Seminar
B0c+p
Br = ( 2.19 ±0.32±0.57 Br = ( 2.19 ±0.32±0.57 ) x 10) x 10- 5- 5
+0.56+0.56- 0.49- 0.49
Stat. Sys. error of Br (c+)
First observation of baryonic 2-body decay
19.6+5.0- 4.4
Belle : PRL 90, 121802 (2003) 78 fb-1
b b c c dd
u u uuu u
d d d d
BB00 cc
pp
b b c c u u
d d
2007/1/9 CYCU Seminar
BB-- CC++ p p --
264±264±20 20 signalsignalss
CC(2455)(2455)00
CC(2520)(2520)00
sidebasidebandnd
32.632.6
12.12.88
+ 6.6+ 6.6 - 5.9- 5.9
+ 5.7+ 5.7 - 5.0- 5.0
Belle 140 fbBelle 140 fb-1 PRL 97, 242001 (2006)-1 PRL 97, 242001 (2006)
B-c+p- 20.1±1.5 ±2.0±5.2
B-c02455 p 3.67 ±0.36
±0.95
B-c02520 p 1.26 ±0.12
±0.33
BF x 10BF x 10-5-5
+0.74+0.74- 0.66- 0.66
+0.56+0.56- 0.49- 0.49
~ 25% of total BF
b b c c u u
d d
Observation of new 2-body decay
2007/1/9 CYCU Seminar
BB0 0 ( (cc++p) p) --
M(c+p) structure in 3, 4 body decays
CC++/0++/0 (2455/2520) excluded (2455/2520) excluded
BB- - ( (cc++p) p) --
B Signals byB Signals byE fitE fit
consistent with 4-body consistent with 4-body MC phase space, MC phase space, fine structures ?fine structures ?
MC 4-body phase spaceMC 4-body phase space
Prelim
inar
y
Prelim
inar
y
2007/1/9 CYCU Seminar
Observation of B+c+c
-K+ Observation of B+c+c
-K+
Unexpected large rate considering the limited phase sapce
Threshold effect?
PRL 97, 202003 (2006)
c+ pK-π+ signal
BF(B+c+c
-K+ ) = (6.5 ± 1.1 ± 3.4) × 10-4+1.0-0.9
2007/1/9 CYCU Seminar
CKM(cc)=VcbVcs* <-> CKM(cp)=VcbVud*
cc 10-3 >> cp 10-5
Observation of B cc
Enhancement for smaller Q ?
Hep-ex/0510074
B+ c0c
+ B0 c-c
+
c π 1%
2007/1/9 CYCU Seminar
Observation of J/p Observation of J/p
J/p J/ppPRD72 051105 (2005)
2007/1/9 CYCU Seminar
Search for inclusive Λc+ production in
tagged B sample
Search for inclusive Λc+ production in
tagged B sample
N(B+) = 200359± 705
N(B0) = 110735± 424
2007/1/9 CYCU Seminar
Determination of BF(B Λc+ X)Determination of BF(B Λc
+ X)
hep-ex/0606026Useful for the understanding ofthe charm counting problem in b decays
BF(B- -> Λc+ X) =(2.8±0.5±0.3 )%
BF(B0 -> Λc+ X) =(5.0±1.0±0.5 )%
BF(B- -> Λc+ X) =(2.1±0.5±0.2 )%
BF(B0 -> Λc+ X) =(1.6±0.9±0.2 )%
+1.0-0.6+1.8-1.0+0.8-0.4+0.6-0.3
2007/1/9 CYCU Seminar
SummarySummary
Exclusive baryonic B decays: Well established after few years of B-factory runningBF(2-body) < BF(3-body) BF(2-body) < BF(3-body) Threshold enhancement in the baryon-Threshold enhancement in the baryon-antibaryon systemantibaryon systemSearching ground for exotic statesSearching ground for exotic statesGood crosscheck for baryonic Good crosscheck for baryonic charmonium decayscharmonium decaysLots of local contributions, both Lots of local contributions, both experimental and theoreticalexperimental and theoretical