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L.Lista INFN Sezione di Napoli. Results of B A B AR experiment on CP violation and B physics. Outline. Experimental set-up Charmonium decays B lifetime measurement Mixing and CP asymmetry Rare B decays Future perspective and Conclusions. (4S). - PowerPoint PPT Presentation
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Luca ListaNapoli, 20/6/01
L.Lista INFN Sezione di Napoli
Results of BResults of BAABBAR experiment AR experiment on CP violation and B physicson CP violation and B physics
Luca ListaNapoli, 20/6/01
OutlineOutline
(4S)• Experimental set-up
• Charmonium decays
• B lifetime measurement
• Mixing and CP asymmetry• Rare B decays• Future perspective and
Conclusions
Luca ListaNapoli, 20/6/01
Has delivered 23.7 fb-1 from Oct. 99 to Nov.2000
Low Energy Ring[e+, 3.1GeV]
High Energy Ring[e-, 9.0GeV]
at Stanford Linear Accelerator Center (California)
center of mass energy M(4S) =10.58 GeV/c2
= 0.56
BaBar
The PEP-II B-FactoryThe PEP-II B-Factory
Luca ListaNapoli, 20/6/01
Performance during the 99-00 runPerformance during the 99-00 run
Parameter Design Achieved Typical# of bunches 1658 1658 553-829LER current 2.14 A 2.14 A 1.35 AHER current 0.75 A 0.92 A 0.73 ABeam size x 222 m 190 m -Beam size y 6.7 m 6.0 m -Fill time 6 mn 8 mn 10 mnTop-off time 3 mn 2 mn 3 mnLER lifetime 4 hrs@2A 3.3 hrs@1.4A 3.0 hrs@1.3AHER lifetime 4 hrs@1A 11. hrs@0.9A 9.0 hrs@0.7ALuminosity 3.0 1033 cm-2s-1 3.3 1033 cm-2s-1 2.5 1033 cm-2s-1
Luca ListaNapoli, 20/6/01
The BaBar detectorThe BaBar detector
ElectromagneticCalorimeter
6580 CsI(Tl) crystals
Instrumented Flux Return19 iron / 18-19 RPC layers
Drift Chamber40 axial stereo
layers
1.5T solenoid
DIRC (PID)144 quartz bars
11000 PMTs
e-
e+
Silicon Vertex Tracker5 layers, 2-sided Si strips
Luca ListaNapoli, 20/6/01
The Silicon Vertex TrackerThe Silicon Vertex Tracker
Beam pipelayer 1,2layer 3layer 4layer 5
Beam bending magnetshigh radiation area
• 5 layers: 20o< <150o;
R= 3.2, 4, 5.4, 9.1-12.7, 11.4-14.4 cm• Single hit resolution: 10-15 m
Luca ListaNapoli, 20/6/01
The Drift ChamberThe Drift Chamber
• 40 axial and stereo layers for Z measurement • small hexagonal cells (11.9 x 19.0 mm)• 80%:20% helium:isobutane
(pT)/pT = 0.13% pT 0.45%
Luca ListaNapoli, 20/6/01
The Cherenkov detector (DIRC)The Cherenkov detector (DIRC)
• Internally reflected Cherenkov radiation
• ~11000 phototubes
Luca ListaNapoli, 20/6/01
• Identification of e±,,0
• Energy resolution:
The Electromagnetic CalorimeterThe Electromagnetic Calorimeter
%9.1%3.2)(4
EE
E
Luca ListaNapoli, 20/6/01
The Instrumented Flux ReturnThe Instrumented Flux ReturnMuon and KL reconstruction18/19 RPC planes~53000 electronic channels
Luca ListaNapoli, 20/6/01
B-countingB-counting
• The determination of B decays branching ratios requires a precise estimate of the number of produced (4S)BB events
• Counting of Multi-Hadron events
• Correction factor: = 0.99620.0027 Different efficiencies for and MH on and off-
resonance• 22,700,000 BB events, 1.7% sys. error
off
offMH
MHBB NNNNN
Luca ListaNapoli, 20/6/01
Inclusive Charmonium DecaysInclusive Charmonium Decays
Effi
cien
cy
muons
pionsE
ffici
ency
b
s, dB0, B
X
J/, (2S), c
d, u
cc
W-
• J/, (2S) and c are reconstructed in final states containing leptons
• Different selection purity for different decays
Luca ListaNapoli, 20/6/01
Inclusive J/Inclusive J/ decays decays
• Inclusive branching ratio:Br(BJ/X) = (1.0440.013 0.028) 10-2
Br(BJ/X dir.) = (0.7890.010 0.034) 10-2
• p*: J/ momentum distribution in the (4S) system B system coincides with (4S) within 250 MeV
p*J/ < 2 GeV/c
J/ ee J/
Luca ListaNapoli, 20/6/01
J/J/ momentum spectrum momentum spectrum
continuum
BB events
Luca ListaNapoli, 20/6/01
J/J/ production in continuum production in continuum
.).%90(103.4
21.021.052.24
/)4(
/
LCB
pb
XJS
XJee
Color singles prediction: A –0.8, 0.8 pb NRQCD (c.o.) prediction: 0.6<A<1.0, 2.8 pb
Angular distribution 1+A cos2*
• First observation of J/ production in continuum BB events rejected by p*>2 GeV/c Rejection of Initial State Radiation
• Ntracks, Etot, R2
• A (all E*) = 0.250.19 • A (p*>3.5 GeV) l= 0.620.39
Luca ListaNapoli, 20/6/01
Br( B (2S) X ) = (0.2750.020 0.029) 10-2
Inclusive Inclusive (2S) decays(2S) decays
p* < 1.6 GeV/c
(2S) ll, J/
(2S) ee (8.1 0.9 0.9)10-3
(2S) (7.0 0.8 0.9)10-3
• Assuming PDG values for (2S) J/:
(2S) ll branching ratio measurement
Luca ListaNapoli, 20/6/01
Inclusive Inclusive c c decaysdecays
• Br(B c1 X) = ( 0.378 0.034 0.026 ) 10-2
• Br(B c1 X dir.) = ( 0.353 0.034 0.024 ) 10-2
• Br(B c2 X) < 0.2110-2 @ 90% C.L.
= ( 0.137 0.058 0.012 ) 10-2
c2 (?) c2 (?)
Luca ListaNapoli, 20/6/01
• Kinematics selection: Energy substituted mass
• Independent on particle mass hypotheses
Energy difference in the center of mass
Exclusive B decaysExclusive B decays
• Motivation: Several channels are used
to constrain the unitarity triangle
Charged modes may exhibit direct CP asymmetry
Probe of non perturbative QCD
Theoretical prediction available for many decays in the factorization hypothesis
2,4 cmBES psm
2sEE B
Luca ListaNapoli, 20/6/01
Golden CP mode: BGolden CP mode: BJ/J/KK00SS
Luca ListaNapoli, 20/6/01
BBJ/J/KK00LL
• KL reconstructed as neutral deposit in the I.F.R. or E.M. Calorimeter
• 1.4 < p*J/ < 2.0 GeV/c
• No KL momentum measurement• E is determined
assuming the mB mass constraint
Luca ListaNapoli, 20/6/01
Selected rare channelsSelected rare channelsFirst observation:B0C1 K*0B0J/ 0
Luca ListaNapoli, 20/6/01
Branching ratios resultsBranching ratios resultsMode Br (10-4)
B0 J/ 0 0.20 0.06 0.02
B0 J/ K*0 12.4 0.5 0.9
B+ J/ K* 13.7 0.9 1.1
B+ J/ K 10.1 0.3 0.5
B0 J/ KKL 6.8 0.8 0.8
B0 J/ KKS00 9.6 1.5 0.7
B0 J/ KKS+ 8.5 0.5 0.6
B0 J/ KAll 8.3 0.4 0.5
B0 c1 K* 4.8 1.4 0.9
B0 c1 K 5.4 1.4 1.1
B+ c1 K+ 7.5 0.8 0.8
B+ (2S) K+ 6.3 0.5 0.8
B0 (2S) K0 6.8 1.0 1.1
Luca ListaNapoli, 20/6/01
BaBar compared to PDG 2000BaBar compared to PDG 2000
Luca ListaNapoli, 20/6/01
J/J/++ / J/ / J/KK++
• Cabibbo and color suppressed tree diagram possible CP asymmetry from penguin contribution
• Unbinned maximum likelihood fit based on kinematical variables:
Br(B+J/)/Br(B+J/K ) =(3.910.78 0.19)10-2
0 2 4 6 8 10
Br(B+ to JpsiPi+) / Br(B+ to Jpsi K+)
CLEOCDFPDGBaBar
( 5.2 2.4 ) %
( 5.0 0.1 ) %
+1.91.7
( 5.1 1.4 ) %
Luca ListaNapoli, 20/6/01
Z
B1 partially reconstructedz ~ 140 m
BB±± and B and B00/B/B00 lifetimes lifetimes
e- e+
9 GeV 3.1GeV
= 0.56z
cB 260 m
B2 fully reconstructedz ~ 60-100 m
• One B is fully reconstructedin a B0 or B mode • Measure both B vertices• Fit for t z/c B
lab
ideally PDF(t) exp(-|t|/B)
• Novel method for asymmetric e+e- machines• Different systematics from previous measurements• Detailed understanding of resolution function needed
Luca ListaNapoli, 20/6/01
The 99-00 data sampleThe 99-00 data sample
B0/B0 B
22.7 106 BB pairs recorded
6967 ± 95 purity 90%
7266 ± 94purity 93%
B0 D(*)+ - D(*)+- D(*)+a1
-
J/K*0
B- D(*)0 - J/K- (2S)K-
Luca ListaNapoli, 20/6/01
Resolution function fitted on data:R(t)=f*Gaus(s)+(1-f)*Gaus(s)Exp(k)
identical for B± and B0/ B0
Unbinned maximum likelihood fit:
psig from mass distribution fit
Bkg description fromside-band events
B0/B0 MC
t residual/ t
Fitting procedureFitting procedure
])O( )())([(
)()(P.d.f./
/
tctRbetap
tRept
bgdt
bgd
sigt
sigbgd
B
Luca ListaNapoli, 20/6/01
Lifetime resultsLifetime results
0 = 1.546 0.032(stat) 0.022(syst) ps = 1.673 0.032(stat) 0.022(syst) ps0 / = 1.082 0.026(stat) 0.011(syst) common resolution
t (ps) t (ps)
background
BB0/B0
preliminarypreliminary
Luca ListaNapoli, 20/6/01
Other lifetime ratio measurementsOther lifetime ratio measurements
Luca ListaNapoli, 20/6/01
• Unitarity relations on matrix
elements lead to a triangle in the complex plane
The Unitarity TriangleThe Unitarity Triangled s b
u
c
t
V V V
V V V
V V V
ud us ub
cd cs cb
td ts tb
0*** tbtdcbcdubud VVVVVV
*
*td tb
cd cb
V VV V
*
*ud ub
cd cb
V VV V
1
B=(1,0)
C=(0,0)
A=(,)
• Quark mixing is described by the CKM matrix
Luca ListaNapoli, 20/6/01
CP violation at asymmetric B factoryCP violation at asymmetric B factory
• coherent production: Y(4S) BB clock starts at 1st B decay
Integrated asymmetry = 0time dependent analysis required
CP violation via mixing interference in bccs
)sin(2sin)()()()()(
)]sin(2sin1[)( /
tmtFtFtFtFtA
tmetF
dCP
CPCP
CPCP
CP
dCPtCP B
@t=0
B0
B0
t (ps)
FF
BB00 J/J/KK00ss
BB00
b
dW W
d
b
t
tB0 B0
Luca ListaNapoli, 20/6/01
The 99-00 data sample: CP modesThe 99-00 data sample: CP modes
J/K0S (
J/K0S ()
(2S)K0S (
CP = -1425 ± 22 purity 94%
J/K0L
CP = +1
199 ± 23 purity 45%
Luca ListaNapoli, 20/6/01
CP modes: FCP(t) e-|t|/
B ( 1 CP sin2sin md t )
Flavour specific modes: Fflav
(t) e-|t|/B ( 1 cos md t )
B1 = B0
ze-e+
B01 partially reconstructed
flavour tagged B02 fully reconstructed
D*+ - or J/K0S
B1 = B0
unmixed B0 B0
mixed B0B0 or B0B0
Mixing and CP asymmetry of BMixing and CP asymmetry of B00/B/B00
Luca ListaNapoli, 20/6/01
Neural network mainly to recover unidentified leptons and use soft pions from D* • NT1: = 7.7 0.4% • NT2: = 13.7 0.5% Total = 68.9 1.0%
Tagging the flavour of the BTagging the flavour of the B00CP/flavCP/flav
Look at the second B in the event• leptons: b l- , b l+
p*>1.0 GeV/c (e±), p*>1.1 GeV/c (±) = 10.9 0.4%• kaons: b K- , b K+
= 36.5 0.7%
Luca ListaNapoli, 20/6/01
Imperfect tagging and resolutionImperfect tagging and resolution
B0
B0
unmixed mixed
e-|t|/B (1 CP
sin2sin md t)
perfect tagging/ resolution
e-|t|/B (1 cos mdt)
imperfect tagging/ perfect resolution
e-|t|/B (1 CP D sin2
sin md t)
e-|t|/B (1 D cos md t)
imperfect tagging/imperfect resolution
e-|t|/B (1 CP D sin2
sin md t) R(t)
e-|t|/B (1 D cos mdt)
R(t)
Luca ListaNapoli, 20/6/01
unbinned maximum likelihood fit:
Free parameters #par sample
sin2 1 CP md 1 flavour
D(B0) & D(B0) 8 flavour & CP
Sig. t resolution 9 flavour & CP
Bkg. t resolution 3 flav & CP side-bands
Bkg. composition 13 flavour side-bands
Bkg. composition 1 CP side-bands
• md : flavour specific sample • sin2 : flavour specific +CP samples
Mainly constrainedby high statflavour sample
Empirical descriptionfitted on data
largest correlation with sin2: 7.6%
Fitting ProcedureFitting Procedure
Luca ListaNapoli, 20/6/01
Flavour misid. measurementFlavour misid. measurement
D = 1 - 2 w Fraction ofwrongly taggedevents
Check w with a time-integrated method (events with |t|<2.5 ps to optimise (w))On the same sample and on ~11000 D*l
(sin2 1/(Q)
kaons
leptons
NT1
NT2
Luca ListaNapoli, 20/6/01
mmdd measurementmeasurement
md =
0.519 ±0.020stat±0.016syst ps-1
preliminarypreliminary
e-|t|/B (1 D cos mdt) R(t)
Luca ListaNapoli, 20/6/01
mmdd measurement: the di-lepton analysismeasurement: the di-lepton analysis
e-e+
zl+or l-
l+or l-
N+ –, – + – N+ +, – –
N+ –, – + + N+ +, – –
A(z)=
Asy
mm
etry
md = 0.499 ± 0.010 ± 0.012 ps-1
Luca ListaNapoli, 20/6/01
preliminarypreliminary
preliminarypreliminary
Luca ListaNapoli, 20/6/01
sin2sin2 results results
sin2 = 0.34 ± 0.20stat ± 0.05syst
sin2=0.25±0.22stat sin2=0.87±0.51stat
Luca ListaNapoli, 20/6/01
sin2ln
(L/L
max
)
CP = -1
CP = +1
sin2=0.25±0.22stat
sin2=0.87±0.51statcombined result
Time dependent asymmetryTime dependent asymmetry
Luca ListaNapoli, 20/6/01
sin2 sin2
Cross-checks: sin2Cross-checks: sin2 on sub-samples on sub-samples
Luca ListaNapoli, 20/6/01
sin2sin2 systematic uncertainties systematic uncertainties
Luca ListaNapoli, 20/6/01
World average for sin2World average for sin2
Luca ListaNapoli, 20/6/01
Unitarity triangle Unitarity triangle
21
sin2 = 0.34 ± 0.20stat ± 0.05syst
Luca ListaNapoli, 20/6/01
J/J/ K* K*00 angular analysis angular analysis
Channels with 0
Channels without 0
f (costr, cosK*, tr) = f1 |A0|2 + f2 |A|||2 + f3|A|2
f4 Im(A||* A) + f5 Re (A0* A||) + f6 Im (A0* A)
J/ rest frameK* decay plane
|A|2 + |A|||2 + |A0|2 = 1
• L=0,1,2 waves• Both CP even and odd amplitudes are present
• Measurement of sin2 is possible from angular analysis
Luca ListaNapoli, 20/6/01
J/J/ K* angular analysis K* angular analysis|A|2 = 0.1600.032 0.014 CP odd, P wave
|A|||2 = 0.2430.034 0.017 CP even, S+D wave
|A0|2 = 0.5970.028 0.024 CP even, S+D wave
= arg(A/A0)=0.170.16 0.07
|| = arg(A|| /A0)=2.500.20 0.08
Time dependent CP asymmetry dilution factor: D = 1 – 2 |A|2 = 0.680.10
(a) Raw measurement(b) Acceptance correction(c) “ “ + mES fit(d) “ “ + (Self) Feed Across
Indication of FSI
Luca ListaNapoli, 20/6/01
B B D*D D*D((**))KK• Study of the bccs transition
• Experimental inclusive estimate from from BDSX, (cc)X, CX, CX (ALEPH, CLEO) Br(bccs) ~ 15.82.8 %
• Theoretical calculation can’t determine this low value together with inclusive s.l. branching ratio (bcW) Three-body B DDK can contribute
• Study of color suppressed modes (B D*D*K)
Color allowed Color suppressed
Luca ListaNapoli, 20/6/01
B B D*D D*D((**))KK
B0 (all modes)NS = 18021
B+ (all modes)NS = 11715
B D*D*K
NS = 8.23.5
• Reconstructed decays: D*+ D0+ D*0 D00
D*0 D0 D0 K-+ D0 K-+0 D0 K-+-+ D+ K-++
• Br(B D*D0K) = (0.280.070.05)10-2
• Br(B D*D*K) = (0.680.170.17)10-2
• Br(B D*D*K) = (0.340.160.11)10-2
First observation of color suppressed mode other than B (charmonium)X
Luca ListaNapoli, 20/6/01
BB00 D* D*++D*D*
• Cabibbo suppressed decay• A measurement in bccd of CP violating
time-dependent asymmetry can be performed from angular analysis Possible penguin contamination
• Measurement of sin2 independent from B0J/K
S
Significant deviations from B0J/KS
measurement of sin2 may be indication of new physics
• Branching ration measurement of B D(*)+D(*)-:
Tree diagram
Penguin contribution
Luca ListaNapoli, 20/6/01
BB00 D* D*++D*D*
Br(B0D*+D*-) = (8.0 1.6 1.2)10-
4
Background sample(6.240.49 expected in signal box)
Signal box(38 events)
Luca ListaNapoli, 20/6/01
Charmless Hadronic DecaysCharmless Hadronic Decays
• Physics motivations
b ud(s)
Vub
Vud(s)
B0 { }
} (K)
d d
u
bB0 { dud(s)
}
} (K)
d
u
tW
W
Vtb
Vtd(s)
Cabibbo suppressed tree diagram
Penguin diagram
• Significant penguin contribution
• Direct CP violation studies
• Measurement of from time-dependent asymmetry + isospin analysis
• Possible field for new physics…
Luca ListaNapoli, 20/6/01
Identifying K and Identifying K and
• Particle identification in the DIRC
D*+D0, D0K-+ control sample
> 3 sigma
p (GeV/c)
p (GeV/c)
Luca ListaNapoli, 20/6/01
Background RejectionBackground Rejection• Continuum events rejection
Combination of event shape variables Thrust axes (B vs rest of event)
• Background control samples E sidebands Off-resonance data D*+D0, D0K+ control sample
signal
D0+
E sidbands background
background
signal
Luca ListaNapoli, 20/6/01
Two Body Charged ModesTwo Body Charged Modes
• B hh
Mode Yield, significanceBranching ratio
K 169 17+12-17, 15.8
(16.7 1.6 +1.2-1.7)10–6
41 10 7, 4.7(4.1 1.0 0.7)10–6
KK 8.2 +7.8–6.4 3.3, 1.3
< 2.510–6 (90%C.L.)
Unbinned Maximum Likelihood Fit results
mES (GeV/c2) E (GeV)
Fit projections(after a likelihood ratio cut)
K
Luca ListaNapoli, 20/6/01
Two Body Charged + Neutral ModesTwo Body Charged + Neutral Modes
• B 0 h
Mode Yield, significanceBranching ratio
37 +15-13, 3.4
(5.1+2.0-1.8 0.8)10–6
K 75 +14-13, 8.0
(10.8 +2.1-1.9
+1.0-1.2 )10–6
Unbinned Maximum Likelihood Fit results
mES (GeV/c2) E (GeV)
Fit projections
Luca ListaNapoli, 20/6/01
Two Body with K-shortTwo Body with K-short
Mode Yield, significanceBranching ratio
K0 59 +11-10, 9.8
(18.2 +3.3-3.0
+1.6-2.0)10–6
K0K 0 (< 8), 0< 2.610–6 (90%C.L.)
K00 17.9 +6.8-5.8, 4.5
(8.2 +3.1-2.7
+1.1-1.2)10–6
Unbinned Maximum Likelihood Fit results
mES (GeV/c2) E (GeV)
Fit projections• B K0h+, K00
Luca ListaNapoli, 20/6/01
Direct CP AsymmetriesDirect CP Asymmetries
• Self tagged modes:
• KA = - 0.19 0.10 0.03 [ -0.35, -0.03 ], 90%C.L.
• KA = 0.00 0.18 0.04 [ -0.30, +0.30 ], 90%C.L.
• KA = - 0.21 0.18 0.03 [ -0.51, +0.09 ], 90%C.L.
• All asymmetries compatible with 0 within current errors
Luca ListaNapoli, 20/6/01
B0
B+h+ < 24 10-6 ( 90% C.L. )B0K0 < 14 10-6
B+K+ ( 62 18 8 ) 10-6
B0K0 < 112 10-6
B0K*0 < 28 10-6
B+0K+ < 39 10-6
B+0+ < 39 10-6
B+K+< 54 10-6
B++< 22 10-6
B0( 49 13 +6-5 ) 10-6
Quasi 2-body and 3-body decaysQuasi 2-body and 3-body decays
Luca ListaNapoli, 20/6/01
BBK, BK, BK* K* • Penguin dominated
B+K+ = (7.7 +1.6-1.4 0.8) 10-6
B+ < 1.4 10-6 (90% C.L.)B+ K*+ = (9.7 +4.2
-3.4 1.7) 10-6
• Possible measure of sin2B0 K*0 = (8.6 +2.8
-2.4 1.1) 10-6
B0 K0 = (8.1 +3.1-2.5 0.8) 10-6
Max Lik. Fit projections
Luca ListaNapoli, 20/6/01
Radiative Penguin: B Radiative Penguin: B K* K*
Signal:
B0 K*0, K*0 K+-
Backgrounds:
e+e- qq
e+e- qq X 0
• Sensitive to top quark couplings CKM matrix elements
Vtd,Vts
• Sensitive to New Physics SUSY, Charged Higgs
• No CP asymmetry in the Standard Model (< 1%) Possible sources
beyond SM
Luca ListaNapoli, 20/6/01
BB00 K* K*00: yield and branching ratio: yield and branching ratio
• Nsignal = 139.2 13.1 events• Br(B0 K*0) = (4.39 0.41 0.27) 10-5
• Br(B K+e+e-) < 12.8 10-6
• Br(B K++-) < 8.3 10-6
• Br(B K*0e+e-) < 24.7 10-6
• Br(B K*0+-) < 25.7 10-6 (90% C.L.)
B0 K*0 K*0 K+
Luca ListaNapoli, 20/6/01
• K*0 KK*0 K
• N(B0) = 72.1 9.4 events• N(B0) = 67.2 9.1 events• ACP = -0.035 0.094 0.022
BB00 K* K*00: CP asymmetry: CP asymmetry
K*0
K*0
-
ws
ws
iiNEWSM
iiNEWSM
eeAAKB
eeAAKB
wsSM
NEW
CP
AA
KBKB
KBKBA
sinsin
22
22
Luca ListaNapoli, 20/6/01
bbss, B, B00 • Semi-exclusive study
Sum of exclusive modesK+n(n=1,2,3)
mES for 0.6 <mhad < 2.0 GeV
• Theoretical exp.: ~ 10
• Br(B0) < 1.94 x 10-6 90% C.L.• PDG: Br(B0 ) < 3.9 x 10-5 90% C.L. (L3)
Branching ratio measurementcoming soon…B0
Luca ListaNapoli, 20/6/01
FutureFuture
• more sin2 modes in preparation (J/K*, cKs,...)
• Run 2 has started in Feb. 2001 and should be endedin June 2002. Run1 + Run2 100 fb-1
• studies of decay modesfor other unitarity angles and analysis started
Luca ListaNapoli, 20/6/01
Conclusions (I)Conclusions (I)• From Oct. 99 to Nov. 2000, BaBar has recorded
22.7 106 BB pairs and a large sample of hadronic B decays has been fully reconstructed.
• High precision measurements of neutral/charged B lifetimes:
0 = 1.546 0.032stat 0.022syst ps = 1.673 0.032stat
0.022syst ps 0 / = 1.082 0.026stat
0.011syst
• competitive result on mixing parameter md:md = 0.519 ± 0.020 ± 0.016 ps-1
• sin2 was extracted from ~500 CP mode events: sin2 = 0.34 ± 0.20stat ± 0.05syst
Luca ListaNapoli, 20/6/01
Conclusions (II)Conclusions (II)• First evidence of charmonium production in continuum• Precise measurements of exclusive charmonium decays
First observation of B0C1 K*0: Br(B0 c1 K*) = 4.8 1.4 0.9
• First observation of color suppressed mode: Br(B D*D*K) = (0.340.160.11)10-2
• Measurements of charmless 2-body decays: Br(B0 K) =(16.7 1.6 +1.2
-1.7)10–6
Br(B0 ) =(4.1 1.0 0.7)10–6
Br(B+ ) =(5.1+2.0-1.8 0.8)10–6
Br(B+ ) =(10.8 +2.1-1.9
+1.0-1.2 )10–6
• Radiative penguin decay: Br(B0 K*0) = (4.39 0.41 0.27) 10-5
ACP = -0.035 0.094 0.022• More statistics will permit to measure to improve the current
measurements and to access more rare channels!
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