Update on Measurement of the angles and sides of the Unitarity Triangle at BaBar

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Update on Measurement of the angles and sides of
the Unitarity Triangle at BaBar

• Martin Simard
• Université de Montréal
• For the BABAR Collaboration
• 12/20/2008
• MIAMI 2008

11/21/2009
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Introduction - Unitarity Triangle
Wolfenstein parameterization
Quark flavor changes can only occur through weak
interactions, via the coupling of a W gauge
boson. Such couplings are proportional to the
relevant CKM matrix elements. In particular, the
probability of a b quark to decay into a u quark
is proportional to Vub2.
Unitarity condition
Each term is O(?3)
This defines the Unitarity Triangle
The main goal of the B-factory is to
over-constrain the unitarity triangle by
measuring angles and sides in as many ways as
possible.
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BABAR Data
End of ?(4S) data Taking (2007) The entire ?(4S)
dataset has a integreted luminosity of about 426
fb-1 (467M BB)
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Constraining the Unitarity Triangle - Sides
Vij2
Sides of the Triangle We measure decay rates.
From radiative decays (b?d?/b?s?) ? Vtd/
Vts inclusive and exclusive decays
From exclusive sl decays Vcb B?Dl?,
B?Dl? Vub B??l?, B??l?, B??()l?, B??l?.
From inclusive B?Xcl? Vcb and B?Xul? decays
Vub
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Vub from B?plv decays untagged
untagged
? Untagged (high stat., most precise)
? Tagged (hadron or semileptonic)
Untagged Analysis
? loose ? reconstruction use the events'
missing momentum as an approximation to
the signal neutrino. (p? pbeams - ?pi)
? Two-Dimensinal Fit ?E EB s/2 and mES
s/4-pB2

• q2 (pB - p? )2 in 12 q2 bins ? Form factor fit

PRL 98, 091801(2007)
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Vub from B?plv decays tagged
? Untagged (high stat., most precise)
? Tagged (hadron or semileptonic)
Tagged Analysis with B?D()l?
Statistical error on the BF is 3 times larger
than the untagged analysis. Compatible result
with the untagged analysis.
348 fb-1
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PRL101, 081801 (2008)
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Vub from inclusive semileptonic decays
Integrated over optimized region in the phase
space
Tagged analysis, use B?D()l? as tags.
347 fb-1
PRL100, 171802 (2008)
Vub values are higher than from exclusive
semileptonic B?plv decays -gt More Data is needed
and improvement from theory is also needed.
theoretical error is the largest error on Vub.
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Vcb with B?Dl? decays
Many methods also for Vcb here is a tag
exclusive analysis
417 fb-1
From PANIC08
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Vcb with B?Dl? decays
BABAR has used three different ways to obtain
Vcb from B?Dl? 1) Fully reconstructed
B0?Dlv (exclusive) 2) Fully reconstructed
B?D0lv 3) Combined fit to partially
reconstructed Dlv and Dlv in D(n)lv events.
Very consistent result
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Vtb/Vts from radiative decays
Vtd is accessible through loops radiative
penguin
See Bruce Schumm talk
Exclusive
Inclusive

• Select high energy
• photons

• veto to photons
• from ?0 and ?

? Yield from ?E and mES
PRL 101 111801,2008
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arXiv 0808.1379, accepted by PRD
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Constraining the Unitarity Triangle - Angles
Vij2
Angles of the Triangle Interference appears
Interference between B mixing and decay
Interference between two decays
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Angle a
Interference between B mixing and b?u Four
solutions ambiguity Isospin analysis to resolve
?a
aeff a ?a
We have to measure A-, A0 and A00
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Angle a - Time-dependent CPV in B?pp-
B0 tagged
Npp 139454
(6.3s)
(3.0s)
B0 tagged
Evidence of direct CP violation
arXiv 0807.4226 hep-ex
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Angle a - B?popo Contrains A00
arXiv 0807.4226 hep-ex
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Angle a - B???
Measured range is compatible with the CKM fit
Smaller A00/A0 means smaller error on ?a
Combined results
Complication due to vector-vector is saved by
fL(??-)1.
PRD78, 071104(R) (2008)
?0?0
B(?0?0) (0.92 0.32 0.14) 10-6
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Angle ß Benchmark sin2ß
CP odd
sin2ß (SM)
Decays
BaBar Results
J/? KL
C 0.026 0.020 0.016 S 0.691 0.029
0.014 ß (21.8 1.3)o
arXiv 0808.1903 hep-ex
HFAG average
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sin2ß
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Angle ß B??K0 and B??K0S
Penguin diagram can change the CPV phase with new
physics This method gives larger errors on ß.
arXiv 0809.1174 hep-ex
?KS (large error)
?KS
?KL
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No evidence of New Physics
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Angle ? B?DK()
Interference between Cabibbo-suppressed b?c and
color-suppressed b?u tree decays
Small CP asymmetry.
D0 and D0 decays into the same final state
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Angle ? B?DK()
D0(D0)?KSpp-, KS??- Dalitz method (Giri,
Grossman, Soffer, Zupan)
Interference comes from overlap region on the
Dalitz plot This method gives the smaller error
DALITZ METHOD
D?KSpp-
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PRD 78 034023 (2008)
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Angle ? B?DK()
D0(D0)? Kp, Kpp0, Kppp ADS method (Atwood,
Dunietz, Soni)
Interference between D0?Cabibbo-favored K- and
D0?Doubly-Cabibbo-suppressed K- This method
gives larger error (Only additional information
to constrain ?)
ADS METHOD
favored
Kpp0
Ratio
Combined mode
suppressed
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PRD 78 034023 (2008)
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Summary
All these observations are in agreement with each
other. The combined fit to all observations leads
to these sides and angles of the unitarity
triangle. No evidence of new physics The SM
describe what we observe.
Kobayashi and Maskawa 2008 Nobel Prize in
Physics for introducing the third quark
generation into the SM which explains CP
violation by quark mixing with the matrix VCKM.
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