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Constraint on CKM angle f2 from B decays

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Constraint on CKM angle f2 from B decays. A. Kusaka (University of Tokyo) ... Oct. 24-28, 2005, Santa Fe, NM, USA. So, why f2 ? Essential to check the standard ... – PowerPoint PPT presentation

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Title: Constraint on CKM angle f2 from B decays


1
Constraint on CKM angle f2 from B decays
PANIC05 Particles and Nuclei International
Conference Oct. 24-28, 2005, Santa Fe, NM, USA
  • A. Kusaka (University of Tokyo),
  • on behalf of Belle collaboration

2
So, why f2 ?
Essential to check the standard KM model.
3
Contents
  • Principle
  • CP violation measurement
  • Event selection
  • CPV measurement of B0?pp
  • CPV measurement of B0?rr
  • Polarization
  • Time dependent fit
  • Constraint on f2
  • Penguin pollution
  • Isospin analysis

4
CKM triangle and f2
f2
VtdVtb
VudVub
f1
f3
VcdVcb
Vtb
Vtd
Vud
B0 ? pp-
Vub
B0 ? rr-
Vtb
Vtd
5
CP violation measurement
6
Data used
253/fb

253/fb (275M BB) until 2004 summer is used.
7
Event selection
  • Event reconstruction
  • p0, r reconstruction (rr)
  • PID (K/p separation)
  • Continuum suppression (modified SFW, flavor
    tagging information)

8
CPV measurement of B0?pp
Spp ?0.67 ?0.16?0.06
App 0.56 ?0.12?0.06
good tag
4s evidence of Direct CPV!
Will be published as PRL 95, 101801
9
CPV measurement of B0?rr
  • Differences from B0?pp
  • Good point
  • Small branching fraction of B0?r0r0 (lt1/20)
    compared with B0?rr- and B?rr0.
  • ?small penguin pollution
  • Bad (difficult) points
  • Decay product contains two p0
  • ?lower efficiency, larger BG
  • Consists of three polarization states
  • ?polarization measurement is essential

10
Polarization
  • B0?rr has 3 polarization states with different
    CP eigenvalues

Transverse
Longitudinal
11
Time dependent fit
Good tag
q1
q-1
Number of events
MBC (GeV)
DE (GeV)
poor tag
good tag
No CP violation
12
Comparison with BaBar
Belle 275M BB
BaBar 227M BB
232M BB
Difference from Belle is 2.3s
Results are consistent with each other.
13
Constraint on f2
14
Penguin pollution

Mixing diagram

15
Isospin analysis (how to get k)
  • BF and asymmetries World average (HFAG)
  • Ahh and Shh Belle measurement above.

16
Situation of B?pp
Due to the large App, one of the triangles
are squeezed.
at 1s
at 90 C.L.
17
Situation of B?rr
Due to the small Br of B0?r0r0, both of
two triangles are squeezed.
at 1s
Good determination of f2 (with only two mirror
solutions)
at 90 C.L.
18
Combined result from Belle
19
Summary
  • This summer, we released new CPV measurement of
    B?rr.
  • Combining B?pp and B?rr, we constrain
    f29312-11? for 1s.
  • The value from direct measurements is consistent
    with that from indirect measurements.

20
(No Transcript)
21
Isospin analysis
  • With the amplitudes and asymmetries of three
    charged modes, f2eff-f2 can be measured.
  • Branching fraction and asymmetries World average
    (HFAG)
  • Ahh and Shh Belle measurement above.

22
  • chi2 of isospin analysis.
  • pp 0.35
  • rr 0.60
  • combined 1.15
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