Update on Measurement of the angles and sides of the Unitarity Triangle at BaBar

Update on Update on Measurement of the Measurement of the

angles and sides of the angles and sides of the Unitarity Triangle at Unitarity Triangle at

BaBarBaBarMartin SimardMartin Simard

Université de MontréalUniversité de MontréalFor the BFor the BAABBARAR Collaboration Collaboration

12/20/200812/20/2008MIAMI 2008MIAMI 2008

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Introduction - Unitarity TriangleIntroduction - Unitarity Triangle

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Wolfenstein parameterization Wolfenstein parameterization

Unitarity conditionUnitarity condition

This defines the Unitarity TriangleThis defines the Unitarity Triangle

Each term is O(λEach term is O(λ33))

The main goal of the B-factory is The main goal of the B-factory is to over-constrain the unitarity to over-constrain the unitarity triangle by measuring angles and triangle by measuring angles and sides in as many ways as sides in as many ways as possible.possible.

(ρ,η) = (ρ,η).(1-λ2/2)

Quark flavor changes can only Quark flavor changes can only occur through weak interactions, occur through weak interactions, via the coupling of a W gauge via the coupling of a W gauge boson. Such couplings are boson. Such couplings are proportional to the relevant CKM proportional to the relevant CKM matrix elements. In particular, the matrix elements. In particular, the probability of a b quark to decay probability of a b quark to decay into a u quark is proportional to |into a u quark is proportional to |VVubub||22..

BBAABBARAR Data Data

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End of Υ(4S) data Taking (2007)End of Υ(4S) data Taking (2007)

The entire Υ(4S) dataset has a The entire Υ(4S) dataset has a integreted luminosity ofintegreted luminosity ofabout 426 fbabout 426 fb-1 -1 (467M BB)(467M BB)

Constraining the Unitarity Triangle - SidesConstraining the Unitarity Triangle - Sides

Sides of the TriangleSides of the Triangle: We measure decay rates.: We measure decay rates. ~ |V~ |Vijij||22

From exclusive sl decaysFrom exclusive sl decays: : |V|Vcbcb|: B|: BD*lD*l, B, BDlDl; ; |V|Vubub|: B|: Bll, B, Bll, B, B(‘)l(‘)l, B, Bll..

From inclusive BFrom inclusive BXXccll: : |V|Vcbcb||and Band BXXuull decays decays : : |V|Vubub||

From radiative decaysFrom radiative decays:: (b(bdd/b/bss) ) |V|Vtdtd|/ |V|/ |Vtsts|| inclusive and exclusive decaysinclusive and exclusive decays

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|V|Vubub| from B| from Bππlv decays untaggedlv decays untagged

PRL 98, 091801(2007)PRL 98, 091801(2007)

Untagged Untagged (high stat., most precise)(high stat., most precise) Tagged (hadron or semileptonic)

Untagged AnalysisUntagged Analysis

loose loose reconstruction: use the events' reconstruction: use the events' missing missing momentum as an approximation to the momentum as an approximation to the signal signal neutrino. (pneutrino. (p = p = pbeamsbeams - - ppii))

Two-Dimensinal Fit Two-Dimensinal Fit E = EE = EBB– s/2 and – s/2 and mmES ES = s/4-|p*= s/4-|p*BB||22

qq22= (p= (pBB - p - p ) )22 in 12 q in 12 q22 bins bins Form factor Form factor fitfit

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untagged

|V|Vubub| from B| from Bππlv decays taggedlv decays tagged

Tagged AnalysisTagged Analysis with with B→D(*)lνB→D(*)lν

PRL101, 081801 (2008)PRL101, 081801 (2008)

Untagged Untagged (high stat., most precise)(high stat., most precise) Tagged Tagged (hadron or semileptonic)(hadron or semileptonic)

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Statistical error on the BF is Statistical error on the BF is 3 times larger than the 3 times larger than the untagged analysis.untagged analysis.

Compatible result with the Compatible result with the untagged analysis.untagged analysis.

348 fb-1

|V|Vubub| from inclusive semileptonic | from inclusive semileptonic decaysdecays

PRL100, 171802 (2008)PRL100, 171802 (2008)

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Integrated over optimized Integrated over optimized region in the phase spaceregion in the phase space

Tagged analysis, use B→D(*)lν as tags.Tagged analysis, use B→D(*)lν as tags.

|V|Vubub| values are higher than from exclusive semileptonic B| values are higher than from exclusive semileptonic Bππlv decays:lv decays:-> -> More DataMore Data is needed and is needed and improvement from theoryimprovement from theory is also needed. is also needed. theoretical error is the largest error on |Vtheoretical error is the largest error on |Vubub|.|.

347 fb-1

BABAR has used three different ways to obtain |VBABAR has used three different ways to obtain |Vcbcb| from B→D*lν:| from B→D*lν: 1) Fully reconstructed B1) Fully reconstructed B00D*D*++lv (exclusive)lv (exclusive) 2) Fully reconstructed B2) Fully reconstructed B++D*D*00lvlv 3) Combined fit to partially reconstructed Dlv and D*lv in D(n)lv 3) Combined fit to partially reconstructed Dlv and D*lv in D(n)lv events. events.

04/20/23 9Very consistent resultVery consistent result

|V|Vcbcb| with B→D*lν decays| with B→D*lν decays

|V|Vtbtb/V/Vtsts| from radiative decays| from radiative decays|V|Vtdtd| is accessible through loops| is accessible through loops: radiative penguin: radiative penguin

B → Xs

B → Xd

PRL 101 111801,2008PRL 101 111801,2008

ExclusiveExclusive

InclusiveInclusive

04/20/23 10arXiv: 0808.1379, accepted by PRDarXiv: 0808.1379, accepted by PRD

veto to photons veto to photons from from 00 and and

Select high energy Select high energy photonsphotons

Yield from Yield from E and mE and mESES

See Bruce Schumm talkSee Bruce Schumm talk

Constraining the Unitarity Triangle - AnglesConstraining the Unitarity Triangle - Angles

Angles of the TriangleAngles of the Triangle: Interference appears: Interference appears ~ |V~ |Vijij||22

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Interference Interference between B mixing between B mixing and decayand decay

Interference Interference between two decaysbetween two decays

Angle Angle αα

Interference between B mixing and bInterference between B mixing and buu

Four solutions ambiguityFour solutions ambiguity

Isospin analysis to resolve ΔαIsospin analysis to resolve Δα

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ααeffeff = = αα + Δα + Δα

We have to measure AWe have to measure A+-+-, A, A+0+0 and A and A0000

Angle Angle αα - - Time-dependent CPV in B→πTime-dependent CPV in B→π++ππ--

Evidence of direct CP violationEvidence of direct CP violation

arXiv: 0807.4226 [hep-ex]arXiv: 0807.4226 [hep-ex]04/20/23 13

(3.0σ)(3.0σ)

(6.3σ)(6.3σ) Nππ: 1394±54

B0 tagged

B0 tagged

Angle Angle αα - - B→πB→πooππoo Contrains A Contrains A0000

arXiv: 0807.4226 [hep-ex]arXiv: 0807.4226 [hep-ex]

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Angle Angle αα - - B→B→ρρρρ

Complication due to vector-Complication due to vector-vector is saved by fvector is saved by fLL(ρ(ρ++ρρ--)~1.)~1.

PRD78, 071104(R) (2008)PRD78, 071104(R) (2008)

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Smaller ASmaller A0000/A/A+0+0 means means smaller error on Δαsmaller error on Δα

B(B(ρρ00ρρ00) = (0.92 ± 0.32 ± 0.14) × 10) = (0.92 ± 0.32 ± 0.14) × 10−6−6

Combined resultsCombined results

ρ0ρ0

Measured range is Measured range is compatible with the CKM fitcompatible with the CKM fit

Angle Angle ββ – – Benchmark sin2β


= sin2β = sin2β (SM)(SM)

C = 0.026 ± 0.020 ± C = 0.026 ± 0.020 ± 0.0160.016S = 0.691 ± 0.029 ± S = 0.691 ± 0.029 ± 0.0140.014ββ = (21.8 ± 1.3) = (21.8 ± 1.3)oo

HFAG averageHFAG average

Decays:Decays:

BaBar Results:BaBar Results:

sin2β04/20/23 16

CP odd

J/Ψ KL

Angle Angle ββ – B→η’K – B→η’K00 and B→ωK and B→ωK00SS

Penguin diagram can change the CPV phase with new physics:Penguin diagram can change the CPV phase with new physics: This method gives larger errors on This method gives larger errors on ββ..

η’Kη’KSSωKωKS S (large error)(large error)η’Kη’KLL

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No evidence of New PhysicsNo evidence of New Physics

Angle Angle γγ – – BB±±→DK→DK(*)±(*)±

Interference between Cabibbo-suppressed Interference between Cabibbo-suppressed b→c b→c and color-suppressed b→u tree decaysand color-suppressed b→u tree decays

DD00 and D and D00 decays into the same final state decays into the same final state04/20/23 18

Small CP asymmetry.Small CP asymmetry.


PRD 78 034023 (2008)PRD 78 034023 (2008)

D→KSπ+π-

DD00(D(D00)→K)→KSSππ++ππ--, K, KSSΚΚ++ΚΚ- - : Dalitz method (Giri, Grossman, Soffer, Zupan) : Dalitz method (Giri, Grossman, Soffer, Zupan)

Interference comes from overlap region on the Dalitz plotInterference comes from overlap region on the Dalitz plot

This method gives the smaller errorThis method gives the smaller error

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DALITZ METHODDALITZ METHOD


PRD 78 034023 (2008)PRD 78 034023 (2008)

DD00(D(D00)→ Kπ, Kππ)→ Kπ, Kππ00, Kπππ : ADS method (Atwood, Dunietz, Soni), Kπππ : ADS method (Atwood, Dunietz, Soni)

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Interference between DInterference between D00→Cabibbo-favored K→Cabibbo-favored K-- and Dand D00→Doubly-Cabibbo-suppressed K→Doubly-Cabibbo-suppressed K--

This method gives larger error This method gives larger error (Only additional information to constrain (Only additional information to constrain γγ))

ADS METHODADS METHOD

Ratio

Combinedmode

favored

suppressed

Kππ0

SummarySummary

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All these observations are in agreement with each other.All these observations are in agreement with each other.The combined fit to all observations leads to these sides and The combined fit to all observations leads to these sides and angles of the unitarity triangle.angles of the unitarity triangle.

No evidence of new physics: The SM describe what we observe.No evidence of new physics: The SM describe what we observe.

KobayashiKobayashi and and MaskawaMaskawa: 2008 Nobel Prize in Physics : 2008 Nobel Prize in Physics for introducing the third quark generation into the SM for introducing the third quark generation into the SM which explains CP violation by quark mixing with the which explains CP violation by quark mixing with the matrix Vmatrix VCKMCKM..

Update on Measurement of the angles and sides of the Unitarity Triangle at BaBar

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