Measurements related to the CKM angle bf1 from BABAR

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Measurements related to the CKM angle b/f1 from
BABAR

• Marc Verderi
• LLR Ecole polytechnique
• For the BABAR collaboration
• XXXIXèmes Rencontres de Moriond
• Interactions ÉlectroFaibles et Théories Unifiées,
  2004

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Introduction

• sin2b measured with very high precision
• but with 4-fold ambiguity on b
• Reduce to a two-fold ambiguity if measuring cos2b
  sign
• Present new method and first measurement of cos2b
  sign with B0?J/y K0 events
• Present CP measurements of penguin dominated
  channels
• B0?fKS
• B0 ?KK-KS B ?KKSKS
• New measurement !
• B0?p0KS
• B0?f0(980)KS
• First measurement !

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Measurement of cos2b signwith B0?J/y K0
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cos2b with B0?J/yK0 ?

• The CP content of the Scalar?Vector Vector
  B0?J/yK0(892) decay is both even and odd.
• cos2b appears through CP-even CP-odd
  interferences in the observables
• d0,d,d? strong phases of the decay amplitudes

• Strong phases determined on neutral and charged
  B?J/yK decays, up to the two-fold ambiguity
• Sign flip of cos(d-d?) and cos(d?-d0) between
  the two strong phases solutions !

? sign of cos2b is ambiguous ! with K(892)
alone.
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Measurement of amplitudes

• Amplitudes measured by angular analysis of
• B0?J/y(Kp-)0 (c.c.)
• B?J/y(KSp) (c.c.)
• B?J/y(Kp0) (c.c.)

BABAR
L82fb-1
B0?J/y(Kp-)
B0?J/y(KSp0)
13114 evts
237651 evts
value stat. syst. A02
0.566 0.012 0.005 A2 0.204 0.015
0.005 A?2 0.230 0.015 0.004 d-d0
2.729 0.101 0.052 d?-d0 0.184 0.070 0.046
B?J/y(Kp0)
B?J/y(KSp)
67027 evts
79133 evts
mES (GeV/c2)
mES (GeV/c2)

• Note BTW the 7.6s significance non-trivial strong
  phase
• d-d?0.5970.0770.017

• With ambiguous solution ( solution II )
• d-d03.554 d?-d02.958

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Accounting for a Kp S-wave

• The ambiguity becomes
• But the ambiguity on g can be broken !

• Kp mass spectrum shows more than the K(892)
• A broad Kp S-wave is known to lie in the K(892)
  region too Nucl. Phys. B 296, 493, (1988)
• Introduction of a new amplitude to describe
  B?J/y(Kp)S-wave
• relative strengths of the P and S contributions
• And a new relative phase
• gdS-d0

BABAR
Kp- L 82fb-1
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Breaking the strong phases ambiguity
BABAR

• Phase of a resonance rotates counterclockwise
  with mass
• Wigner causality principle !
• In the K(892) region
• P-wave phase moves fast
• S-wave phase moves slow
• ? gdS-d0 must rotate clockwise
• Fit for P and S wave intensities and g by Kp mass
  bin, fixing d-d0 and d?-d0 to
• Solution I (2.729, 0.184)
• Solution II (3.554, 2.958)
• Physical behaviour observed for solution II !

P-wave intensity
Kp- L 82fb-1
S-wave intensity
sol. I
gdS-d0
sol. II
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Comparison with LASS data

• Is this behaviour expected for a Kp S-P phase ?
• Compare with LASS data
• Kp?Kp(n)
• I1/2 contribution
• Global phase p added to LASS data points
• Remarkable agreement!
• A bit surprising because very different processes
  !
• Keep Solution II as the physical solution !
• Note solution I is the one reported up to now !

BABAR
LASS data
sol. I
sol. II
Kp- L 82fb-1
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Measurement of cos2b sign

• cos2b measured by a time and angular analysis of
  the B0?J/y(KSp0)0 sample
• 104 tagged events (low statistics !)
• Fit with sin2b free in the fit
• Fit with sin2b 0.731

BABAR
cos2b0.68
cos2b3.32
Dt (ps)

• Assuming sin2b and cos2b comes from the same
  angle 2b, from Monte Carlo
• Exclude cos2b
• -(1-sin22b)1/2-0.68
• _at_ 89 CL

PRELIMINARY !!!
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CP measurements with penguin dominated modes
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Windows to new physics

• Decay time distribution
• In naive picture
• C0
• S-hf.sin2b
• In the following, report C and S values.

• Penguin dominated modes, e.g. B0?fK0,
• are sensitive to new physics through the loop.
• Modes measure a sin2beff value which may differ
  from sin2b in SM by at most 0.2 to 0.4, depending
  on the mode

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B0?fKS B0?fKL
BABAR

• In SM, measures
• sin2b, for B0?fKS
• -sin2b, for B0?fKL

B0?fKS
BABAR
B0?fKL
L108fb-1 B0?fKS 709 events
BABAR
B0?fKL
5216 events
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B0?KK-KSB?KKSKS
L111fb-1

• 3 body decay B0?KK-KS
• (excluding B0?fK0 events)
• Together measurement of branching ratios to
  determine CP-even fraction, through isospin
  symmetry Belle Collaboration, Phys. Rev D69,
  012001 (2004)

BABAR
B0?KK-KS 20116 events
B?KKSKS 12214 events
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CP with B?KKKS

• even determination
• Br(B0?KK-K0)
• (23.82.01.6)10-6
• Br(B?KKSKS)
• (10.71.21.0)10-6
• even0.980.150.04
• Consistency check with angular distribution
• decay measures sin2b

BABAR

• Also, first measurement of CP-violating charge
  asymmetry with B?KKSKS
• ACP(B?KKSKS) -0.042 0.114(stat) 0.02(syst)

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B0?p0KS

• Measures sin2b in SM
• KS direction used to determine B0 vertex
• Constrain in x-y to beam-spot
• Cross checks with B0?J/yKS and B?pKS, ignoring
  J/y or p
• B0 lifetime.

BABAR
L113 fb-1 12216 events
BABAR
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B0?f0(980)KS ?pp-
?

• Structure of scalar meson 0(980) obscure
• But recent studies hep-ph/0011191 (2000) favor
  usual qq state
• Decay can be dominated by b?sss penguin since
• ss sizeable
• b?uus tree doubly Cabbibo suppressed compared to
  leading penguin.
• In this case, decay measures

• Quasi 2-body analysis
• Cut on the Dalitz plot to reduce contributions
  from r0 and f0(1370)
• First observation of B0?f0(980)KS !

BABAR
L111fb-1 9414(stat)6(syst) evts
Total Continuum All bgk.
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CP fit of B0?f0(980)KS

• Consistency check fitting pp- mass spectrum with
  relativistic Breit-Wigner
• CP fit result

BABAR
L111fb-1
BABAR
Total Continuum All bgk.
Total Continuum All bgk.
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Summary of sin2b measurements from BABAR

• Shows all sin2b measurements from BABAR
• Including those not presented today

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Summary

• Many new results !
• New method to break the B?J/y K strong phases
  and related cos2b sign ambiguities
• Preliminary measurement of cos2b sign.
• CP measurements with
• New measurement of KK-KS and first measurement
  of KKSKS
• First measurement with f0KS
• Results being published
• KSp0 submitted to PRL
• Final result for fK0

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and conclusion

• At the present level of statistics, from cos2b
  sign measurement and CP measurements in penguin
  modes, BABARs picture of sin2b is Standard
  Model like.

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Backup
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C
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cos2b contour plots
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BELLE
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Introduction

• b?ccs
• B0?J/y,Y(2S),cc1 KS
• High precision measurement of sin2b
• B0?J/y K0
• Measurement of cos2b sign
• b?ccd
• Possible penguin pollution
• B0?D()D(), J/y p0
• Measure sin2b

• b?sss
• Penguin dominated modes
• Sensitive to new physics
• Measure sin2b in the SM
• B0?fKS
• B0 ?KK-KS B ?KKSKS
• B0?hKS
• B0?p0KS
• B0?f0(980)KS