charmless quasi-two-body modes at babar

18/08/04 Fernando Palombo , ICHEP 2004

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Charmless Quasi-two-Body Charmless Quasi-two-Body Modes at BaBarModes at BaBar

Fernando PalomboDipartimento di Fisica and INFN, Milan

for The BaBar CollaborationICHEP’04 August 16 – 22 , 2004 Beijing, China


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OutlineOutline

• Motivation• Analysis Technique : Overview• B0 →

• B+ → +, B+ → +

• B0 → • B0 → a1(1260) -

• B0 →ρ0 KS

• B0 → KS KS KS

• Conclusion

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MotivationMotivation We look to processes dominated by

penguin loops or CKM-suppressed decay (Rare Decays)

An optimal place for measurements sensitive to new physics ( new contributions to the penguin amplitude beyond the SM)

Check of QCD Factorization, Perturbative QCD, Flavour SU(3)


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Analysis Technique : Analysis Technique : OverviewOverview

Unbinned Maximum Likelihood (ML) Fit Kinematic and event shape variables Apply loose cuts to keep side-bands for background fitting Main background : e+e- → q q continuum (q = u,d,s,c) fit accounts also for B B background Extract from ML fits: yields, charge asymmetries, efficiencies, PDF parameters Several Crosschecks “Toy MC” experiments, control samples Analyses presented in this talk done in Q2B approximation


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BB00 →→

Expected dominated by b → s loop amplitudes

K+ K, *+, sK* enhanced + K K*+ * suppressed

(Lipkin,199)

ICHEP/11-0936 BaBar-Conf-04/023

Interference

A. Ali et al., PRD59, 014005 (1999), M. Z. Yang et al., NPB609,469 (2001)

M. Beneke et al., NP B651,225(2003), H.K. Fu et al., PRD69,074002 (2004)

Chiang et al., PRD69,934001 (2004)


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New Measurement of BNew Measurement of B00 →→

New measurement with 182 106 BB pairs .

Predicted large charge asymmetryChiang et al., PRD69,034001(2004)

Now observed by BaBarPRL 92, 061801 (2004)

ηK0


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BB++→ → + + and and BB++→ → ++

Expected dominated by a CKM-suppressed tree diagram

Vub

ICHEP /11-0936 BaBar-Conf-04/023


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New Measurements of BNew Measurements of B++→ → + + and and BB++→ →

++

+ +

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182 106 BB pairs used in this analysis_


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New Measurement of BNew Measurement of B00 →→

Remeasurement done with 182 106 BB pairs

As expected we improve upper limits.Very interesting for calculation of upper bound on ΔS in B0 decay modes dominated by penguins

Subm.to PRL

Measurements done with 89 106 BB pairs_

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Isoscalars ULs and Isoscalars ULs and ΔS

Gronau, Rosner,Zupan hep-ph/0403287

With new ULs in B decays to isoscalar pairs measured by BaBargreat improvement in the bounds of ΔS = S – sin 2 β S is the coefficient of sin term in time evolution of the systemsin 2 β is S measured in B0 decays to charmonium K0

BaBar new measurement in η'K0 : S=0.27 ±0.14 ±0.03 ( see Hoecker C=-0.21± 0.10 ±0.03 talk, this conf )

see also :Grossman et al. PRD68 ,015004 (2003)

Previous bound

New bounds

2003 BaBar + Belle average η'K0


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BB00→ → aa11++- - (a(a11→→++++--))

Rare decay with a BF not yet measured.

These decays can be used to study CP asymmetryfor an independent measurement of sin 2α

But first we have to measure the BF to see if there is any signal.

Analysis done with a statistics of 124 106 BB pairs.

Simple analysis done in Quasi-2-Body approximation.Dalitz plot analysis is in progress

ICHEP/11-0969 BaBar-Conf-04/002

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Measurement BMeasurement B00→ → aa11- - ( a( a11→→++++- - ))

Yield 472 ±46

Br(B0→a1+ -) = (42.6 ± 4.2stat ± 4.1syst ) 10-6

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Observation of this decay stat. sign. > 10 σ

m = 1.19 ± 0.02 GeV/c2 Γ = 312 ± 55 MeV/c2

a1a1


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BB00→→ρρ00KK00SS

Penguin dominated mode :

Another candidate for measuring CP-violating asymmetries (sin 2 β ) in penguin-dominated modes

Analysis done using 227 106 BB pairs

Several classes of Charmless and Charm backgrounds described by PDFs in ML fit

ICHEP/11/0992 BaBar-Conf-04/046


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BB00→→ρρ00KK00SS

Yield : 99 ± 19

Br(B0→ρ0KS ) = (5.1 ± 1.0 ± 1.2) 10-6

Evidence of this mode at 3.5 σ

(ρ0KS + σ KS ) signal at 6.1 σ

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B B →→KKSS KKSS KKSS00

Penguin dominated mode :

This decay is not Cabibbo-suppressed

Already measured by Belle with 78 fb-1Br(BB00→→KKSS K KS S KKS S )) = (4.2 ± 0.8) 10-6

This measurement done with 211 106 BB pairs

000 +1.6 -1.3

0000 00

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BB00→→KK00SS KK00

SS KK00SS

Yield 71 ± 9 ε = 5.2 % syst. err = 13 %

Br(B0→ KS KS KS ) = (6.5 ± 0.8 ± 0.8) 10-6

Significance > 10 σ

ICHEP/11-0929 BaBa-Conf-04/032

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ConclusionConclusion

Observations of B0 → ηK0 , ηρ+, η'+ , a1+ -

Evidence for B0 → ρ0 at 3.5 σ

B0 → 3 seen with stat. sign. > 10 σ No evidence in these decay modes for direct CPV Severe tests of factorizion models

(predictions of BF, charge asymmetry, etc)

all new results are preliminary

0 KS

KS

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charmless quasi-two-body modes at babar

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