Title: Constraint on CKM angle f2 from B decays
1Constraint 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
2So, why f2 ?
Essential to check the standard KM model.
3Contents
- 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
4CKM triangle and f2
f2
VtdVtb
VudVub
f1
f3
VcdVcb
Vtb
Vtd
Vud
B0 ? pp-
Vub
B0 ? rr-
Vtb
Vtd
5CP violation measurement
6Data used
253/fb
253/fb (275M BB) until 2004 summer is used.
7Event selection
- Event reconstruction
- p0, r reconstruction (rr)
- PID (K/p separation)
- Continuum suppression (modified SFW, flavor
tagging information)
8CPV 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
9CPV 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
10Polarization
- B0?rr has 3 polarization states with different
CP eigenvalues
Transverse
Longitudinal
11Time dependent fit
Good tag
q1
q-1
Number of events
MBC (GeV)
DE (GeV)
poor tag
good tag
No CP violation
12Comparison with BaBar
Belle 275M BB
BaBar 227M BB
232M BB
Difference from Belle is 2.3s
Results are consistent with each other.
13Constraint on f2
14Penguin pollution
Mixing diagram
15Isospin analysis (how to get k)
- BF and asymmetries World average (HFAG)
- Ahh and Shh Belle measurement above.
16Situation of B?pp
Due to the large App, one of the triangles
are squeezed.
at 1s
at 90 C.L.
17Situation 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.
18Combined result from Belle
19Summary
- 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)
21Isospin 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