Hadronic B Decays at BELLE and BABAR

1
Hadronic B Decays at BELLE and BABAR
Sheng-Wen Lin National Taiwan University

• B ?K?, ?? and KK
• Ratios of Branching Fractions
• Observation of B ?KK0 and B0 ?K0K0
• ACP of K?-, K?0 and ??0
• B ??K0
• B0??0?0
• B0? ?K
• B0?a0-p and a0-K
• Conclusion

2
Puzzle of K?

• Buras, Fleischer et al, APO B36(2005)2015-2050
• Within the SM
• Rc-Rn0, Acp(Kp-) - Acp(Kp0)0
• New Physics
• B0?p0K0 and B?p0K may have color-allowed EW
  penguins form
• Rc and Rn have sizeable effects by EW
  penguin
• Described theoretically by q and ?
• q strength of the EW penguin with respect to
  the tree contribution
• ? CP-violation phase

3
Theory of KK

• B ?K0K and B0?K0K0 are dominated by b ?d
  penguin
• B0 ? K K- is from annihilation diagram
• J.-M. Gerard and W.-S. Hou, PLB 253, 478 (1991)
• BF of B ?K0K and B0?K0K0 are of order 10-6
• Sizable asymmetry of O(45) of B0?K0K0
• C.-H. Chen and H.-n. Li, PRD 63, 014003(2001)
• There is no CP asymmetry in the B0?K0K0 mode and
  small BF for B0 ? K K- is expected
• ?if no strong FSI effect

4
K? - and ?? -
B???-
hep-ex/0609015
B?K?-
Sig(red)
Con(dash)
rareB(hatched)
?? -?K?- (dotted)
PRD 75, 012008 (2007)
sPlots
Consider the final state radiation effects in
these modes
5
BF of Kp0,pp0 and K0p0
hep-ex/0609015
K0?0
???0
K??0
???0
K??0
K0?0
hep-ex/0607106
hep-ex/0607096

• Simultaneous fit for pp0 and Kp0 at Belle and
  BaBar
• Use MES and Mmiss to extract yield for K0p0 at
  BaBar

6
B?KK Observation of b ? d penguin
KK-
K0p
5.3s
K0K
5.3s
7.3s
K0K0
6.0s
PRL 97, 171805(2006)
hep-ex/0608049(submit to PRL)
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Summary of B ?hh
8
(No Transcript)
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New Electroweak Penguins in the Ratios Rn and Rc
q measures the importance of the EW penguins
with respect to the tree-diagram-like
topologies ? CP-violating weak phase
SM
Old WA Data
Buras, Fleischer et al, APO B36(2005)2015-2050
10
Direct CP Asymmetries(Belle)
Kp- -0.0930.0180.008 (4.7s) Kp0
0.070.030.01 (2.3s) pp0 0.070.060.01 Acp(Kp
-) - Acp(Kp0) ?4.4s
Preliminary
The other decay modes
hep-ex/0608049(submit to PRL)
11
Direct CP Asymmetries(BaBar)
Kp- -0.1080.0240.007(4.3s) (254267) Kp0
0.0160.0410.010 pp0 -0.0190.0880.014 Acp(Kp
-) - Acp(Kp0) ? 2.6s
hep-ex/0607106

• Observation of Kp- Direct CP asymmetry
• -0.1070.0180.007-0.004 (5.5s) (437282)
• Using dE/dx as a discriminating variable in the
  M.L. fit
• cos?Spherlt0.9? cos?Spherlt0.8
• Total increase in rec. eff. is 52

hep-ex/0703016(submit to PRL)
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BF of B??K0 and search for B? K0K

• ?K0
• Pure penguin b?s PV decay
• Branching Fraction
• (8.0 1.4 -1.3 0.5)x10-6 (7.9s)
• CP asymmetry
• (-12.216.62.0)
• Observation of this mode
• BF and ACP are consistent with SM

hep-ex/0702043
cos??
Mpp0

• Dominated by the b?dg penguin amplitude
• b?d analogue of B??K0 (both VP and penguin)

?K0
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Evidence for B0??0?0

• tree contribution is color-suppressed
• ?decay rate is sensitive to the penguin amplitude
• Complete the isospin triangle
• Branching Fraction
• B0??0?01.070.330.19 x10-6 (3.5s)
• Upper limit
• B0??0f0(980),f0?pp- lt 0.53 x 10-6
• B0?f0(980)f0(980),f0?pp- lt 0.16 x 10 -6
• longitudinal polarization fraction
• 0.87 0.13 0.04

hep-ex/0612020
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B0 ? ?K0
384 M BB
Full amplitude analysis
PRL 98 051801, 2007
H1
H2
?K(892)
?K(1430)
15
Search for B0?a0-pand a0-K
Preliminary
a0-p
a0-K
a0(1450)-p
a0(1450)-K
Evidence taht a0(980) meson is a four-quark state
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Conclusion

• Kppuzzle
• Two ratios Rn, Rc
• ? Belle consistent with SM prediction
• BaBar also move towards SM prediction
• Significant difference between Acp(Kp-) and
  Acp(Kp0)
• ?Large colour-suppressed trees
• Observation of b ?d modes and B??K0
• Only from BaBar
• Evidence of B0??0?0 at BaBar
• fL0.5 in B??K, implies A0 ? A1 gtgt A-1
• a0(980) meson like a four-quark state

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Backup
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B signal reconstruction
The signal yield are usually extracted by Mbc and
?E

• Beam constrained mass
• Precise beam energy known from accelerator
• Lower error on momentum resolution
• Energy difference
• Asymmetry shape and shift due to energy loss
• Ebeam run dependent beam energy
• EB and PB are the reconstructed energy and
  momentum of the B candidates
• in CM frame

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PHOTOS
E. Barberio, Z. Was Comput. Phys. Commun.
79,291 (1994)

• Final state radiation (FSR) effects
• PHOTOS included in our MC
• for all B?hh modes.
• Systematic uncertainty of PHOTOS
• in B?hh now calculated 1/million
• (negligible for non-SUPERB statistics)

• PHOTOS v 2.13
• Interference on,
• double photon on,
• Ecut26MeV

Impact on eff w/o PHOTOS
pp- Kp- hp0
9.4 5.8 3.6
G.Nanava and Z.Was hep-ph/0607019
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Calibration of signal PDF
Signal PDF
MC
Signal MC sample
Data
The PDF of data and MC are the same ?
Control sample Like B- ?D0?-
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Correction of efficiency
22
2D Ext. Un-binned ML Fit
23
Systematics of Br(B?hh)
Systematics of FSR is about 1.0
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Systematics of Acp

• detector bias of Kp0,pp0 from qq bkg in (?E,
  mbc)
• detector bias of Kp from D ? D0(?Kp)p

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B0 ? ?0?0
Time information
On time 9000lttlt11000
Too late
Too early

• Difficult to model the distribution for
  off-time QED background with MC
• Re-process the raw-data for timing information

Off-time events
5.28GeV/c2
Bhabha events
26
BF. of B0 ??0?0
hep-ex/0610065
277M BB
535M BB