Wolfgang Menges, Queen Mary Measurement of the CKM Sides at the B-Factories Wolfgang Menges On behalf of the BaBar and Belle Collaborations Queen Mary, University of London, UK • CKM matrix and Unitarity Triangle • Semileptonic B decays (|V ub |, |V cb |)
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Wolfgang Menges, Queen Mary Measurement of the CKM Sides at the B-Factories Wolfgang Menges On behalf of the BaBar and Belle Collaborations Queen Mary,
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Measurement of the CKM Sidesat the B-Factories
Wolfgang MengesOn behalf of the BaBar and Belle Collaborations
Queen Mary, University of London, UK
•CKM matrix and Unitarity Triangle
•Semileptonic B decays (|Vub|, |Vcb|)
•Summary
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ud ub
cd cb
V V
V V
•weak and mass eigenstates of the quarks are not the same
•changes in base are described by unitarity transformations
•Cabibbo Kobayashi Maskawa(CKM) matrix
1-c2 c A c
3(-i)
-c 1- c2/2 A c
2
Ac3(1- -i) -A c
2 1 + O(c
4) [ c= sinc ]CP violation
CKM Matrix and Unitarity Triangle
1
td tb
cd cb
V V
V V
•angles can be measured with CPV of B decays
•sides from:- semileptonic B decays (|Vcb| and |Vub|)- rare B decays (|Vts|, |Vtd| and |Vub|)
0ud ub cd cb td tbV V V V V V
Wolfenstein parametrisation
See talk by Y. Kwon
See talk by Y. Iwasaki
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Unitarity Triangle Fits
Bd mixing: md
Bs mixing:ms / md
J/K0: sin2
bul: |Vub|
bcl: |Vcb|
kaon decays: εK
http://ckmfitter.in2p3.fr
charmless two-body:
interference in BDK:
Sides complementary to angles|Vub|/|Vcb| complementary to
sin2
ρ
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B Factories
Čerenkov Detector(DIRC)
144 quartz bars11000 PMTs
1.5 T
solenoid
ElectroMagnetic Calorimeter
6580 CsI(Tl) crystals
Drift CHamber40 stereo
layers
Instrumented Flux Return
iron/RPCs/LSTs(muon/neutral hadrons)
Silicon Vertex Tracker5 layers, double sided
strips
e+ (3.1 GeV)
e- (9 GeV)
BaBar Detector
PEPII:Lpeak ~ 1034cm-2s-
1
Lint ~ 330 fb-1
KEKB:Lpeak ~ 1.6 1034cm-
2s-1
Lint ~ 560 fb-1
TOF counter
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Semileptonic B Decays
uX
B
u quark turns into one or more hadrons
B → Xlv decays are described by 3 variables
2
2
( ) 1
( ) 50ub
cb
Vb u
b c V
q2 = lepton-neutrino mass squaredq2 = lepton-neutrino mass squared
mX = hadron system massmX = hadron system mass
El = lepton energyEl = lepton energy
P+ = EX - |pX| P+ = EX - |pX|
b
,c u
W
,cb ubV V
Semileptonic B decays allow measurement of |Vcb| and |Vub| from tree level processes.
Presence of a single hadronic current allows control of theoretical uncertainties.
b clv is background to b ulv:
favoured by theory
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|Vcb| from b clv decays
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•Operator Product Expansion (OPE): double expansion in s and mb
-1
•Fit moments of inclusive distributions – lepton energy, hadron invariant mass– Determine OPE parameters and |Vcb|
•Measurements from B Factories, CDF, Delphi•Recent measurements from Belle: