Page 1

B0Ks + quasi 2 body modes

Koji Hara(Nagoya University)

CKM2006 WG4 from charmless B decays

Page 2

Analyses Reviewed

• Belle K0 hep-ex/0608039 (Accepted by PRL)K0 ,f0KS hep-ex/0609006

• BaBar KS hep-ex/0607101KS hep-ex/0608051

Page 3

B0KS Analysis Procedure1. Event selection

Flavor tagging, vertex reconstruction

2. Loose Continuum suppression Based on event shape variables

3. Nsig extraction and CP fit

Fit E-Mbc-M-event shape-cosH and t Separate fits: Nsig CP fit (Belle) Nsig and CP simultaneous fit (BaBar)

Page 4

B0KS Signal Yields

535 M BB pairsNsig 118+-18

Eff. 17%

LR>0.85

LR0.85

347 M BB pairsNsig 142+-17

Eff. 23%

Page 5

B0KS tCPV result

S=+0.11+-0.46+-0.07A=-0.09+-0.29+-0.06

S=+0.62+0.25-0.30+-0.02

C=-A=-0.43+0.25-0.23+-0.03

Dominant systematic errors:

signalt ., BB BG, tag-side interference

Dominant systematic errors:

BG frac., t resol., tag-side interference

Page 6

B0K0 (Belle)

• Selected K+K- mass region |MKK-M|10MeV/c2

• K+K-K0 non-resonant contribution is estimated from the separate Dalitz analysis to be 2.75+-0.14%.

• f0K0 contribution is treated as systematic error.

• BaBar did KKK0 time-dependent Dalitz analysis.Di Marco’s talk in WG4-14-PM1

Page 7

B0KS Yields

• Fit Mbc-E-LR(event shape+cosH)LR

LR>0.5

LR0.5

Data sample: 535 M BB pairsNsig: (K+K-)Ks, Ks+- 246+-18 (K+K-)Ks, Ks00 40+-9 (KsKL)Ks, Ks+- 21+-7

Page 8

B0KL Yields

• Fit PBcms-LR

Data sample: 535 M BB pairsNsig: 114+-17

LR

Page 9

B0 K0 tCPV result S = + 0.50 0.21 0.06A = + 0.07 0.15 0.05Background

subtracted

SKs = + 0.50 0.23

AKs = + 0.11 0.16

SKL = - 0.46 0.56

AKL = - 0.15 0.38

Results for Ks KL separate fit

Dominant systematic errors:

BG frac. t resolution, tag-side interference

Page 10

B0f0Ks (Belle)

• Selected f0+- mass region

0.890<M<1.088 GeV/c2

• Other B0 KS decay background is estimated from separate fit to MDistribution

Page 11

B0 f0Ks Yields

Data sample: 535 M BB pairs

Nsig: 377 25

LR

LR>0.5

Fit Mbc-E-LR

Page 12

B0f0KS tCPV result

-S = +0.18 0.23 0.11A = -0.15 0.15 0.07

Dominant systematic errors:

Ks BG (interference effect, CPV)

Page 13

B0KS (BaBar)

• Selected 0+- mass region0. 4<M<0.9 GeV/c2

• B decay BGs are estimated from MC

Page 14

B0KS Yields

Fit MES-E-NN-cos-M-t

Data sample:227 M BB pairs

Nsig 111+-19

Page 15

B0KS tCPV result

S = +0.20 0.52 0.24C=-A = +0.64 0.41 0.20

Dominant systematic errors:

Interference, PDF uncertainties, mis-recon and fit bias

Page 16

Summary • S=(-fsin21eff) values are consi

stent with sin21 from bccs.

• BaBar Ks tCPV errors are smaller than Belle.

– Similar analysis method is used.

– Possible reason: selection, boost factor, statistical fluctuation.

• Quasi 2 body analyses has large systematic errors from B decay BG components.

– Especially in KS modes– Time-dependent Dalitz analysi

s will be necessary for improvement.