Cp violation measuring matter anti matter asymmetry with babar
This presentation is the property of its rightful owner.
Sponsored Links
1 / 49

CP Violation Measuring matter/anti-matter asymmetry with BaBar PowerPoint PPT Presentation


  • 48 Views
  • Uploaded on
  • Presentation posted in: General

CP Violation Measuring matter/anti-matter asymmetry with BaBar. Wouter Verkerke University of California, Santa Barbara. Outline of this talk. Introduction to CP violation A quick review of the fundamentals. CP-violating observables Experiment and analysis techniques

Download Presentation

CP Violation Measuring matter/anti-matter asymmetry with BaBar

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Cp violation measuring matter anti matter asymmetry with babar

CP ViolationMeasuring matter/anti-matter asymmetry with BaBar

Wouter Verkerke

University of California, Santa Barbara

Wouter Verkerke, UCSB


Outline of this talk

Outline of this talk

  • Introduction to CP violation

    • A quick review of the fundamentals.

    • CP-violating observables

  • Experiment and analysis techniques

    • Accelerator and detector (PEP-II and BaBar)

    • Event selection, measuring time dependent CP asymmetries

  • Selection of (recent) BaBar CP violation results

    • The angle b

    • The angle a

    • The angle g

Wouter Verkerke, UCSB


Why is cp violation interesting

Why is CP violation interesting?

  • It is of fundamental importance

    • Needed for matter/anti-matter asymmetry in the universe

    • Standard Model CP-violation in quark sector is far too small to explain matter asymmetry in the universe

  • History tells us that studying symmetry violation can be very fruitful

  • CP violating processes sensitive to phases from New Physics

  • Can CP-violation measurements at the B factories break the Standard Model in this decade?

    • Measure phases of CKM elements in as many ways as possible

Wouter Verkerke, UCSB


The c abibbo k obayashi m askawa matrix

d

s

b

u

c

t

The Cabibbo-Kobayashi-Maskawa matrix

  • In the Standard Model, the CKM matrix elements Vij describe the electroweak coupling strength of the W to quarks

    • CKM mechanism introduces quark flavor mixing

    • Complex phases in Vij are the origin of SM CP violation

Mixes the left-handed charge –1/3 quark mass eigenstates d,s,b to give

the weak eigenstates d’,s,b’.

l3

l

l

l2

l3

l2

l=cos(qc)=0.22

CP

The phase changes signunder CP.

Wouter Verkerke, UCSB

Transition amplitude violates CP if Vub ≠ Vub*, i.e. if Vub has a non-zero phase


The unitarity triangle visualizing ckm information from b d decays

d

s

b

u

c

t

The Unitarity Triangle – Visualizing CKM information from Bd decays

  • The CKM matrix Vij is unitary with 4 independent fundamental parameters

  • Unitarity constraint from 1st and 3rd columns: i V*i3Vi1=0

  • Testing the Standard Model

    • Measure angles, sides in as many ways possible

    • SM predicts all angles are large

CKM phases

(in Wolfenstein convention)

Wouter Verkerke, UCSB


Observing cp violation

Bf

Observing CP violation

  • So far talking about amplitudes, but Amplitudes ≠ Observables.

  • CP-violating asymmetries can be observed from interference of two amplitudes with relative CP-violating phase

    • But additional requirements exist to observe a CP asymmetry!

  • Example: process Bf via two amplitudes a1 + a2 = A. weak phase diff. g 0, no CP-invariant phase diff.

Bf

A=a1+a2

A=a1+a2

a2

A

+g

a1

a1

-g

A

a2

|A|=|A|  No observable CP asymmetry

Wouter Verkerke, UCSB


Observing cp violation1

Bf

Observing CP violation

  • Example: process Bf via two amplitudes a1 + a2 = A. weak phase diff. g 0, CP-invariant phase diff.d 0

Bf

A=a1+a2

A=a1+a2

+g

d

d

A

-g

a2

A

a2

a1

a1

|A||A| Need also CP-invariant phase for observable CP violation

Wouter Verkerke, UCSB


Cp violation decay amplitudes vs mixing amplitudes

f = b

f = b

CP violation: decay amplitudes vs. mixing amplitudes

  • Interference between two decay amplitudes gives two decay time independent observables

    • CP violated if BF(B  f) ≠ BF(B  f)

    • CP-invariant phases provided by strong interaction part.

    • Strong phases usually unknown  this can complicate things…

  • Interference between mixing and decay amplitudesintroduces decay-time dependent CP violating observables

    • Bd mixing experimentally very accessible: Mixing freq Dmd0.5 ps-1, t=1.5 ps

    • Interfere ‘B  B  f’ with ‘B  f’

    • Mixing mechanism introduces weak phase of 2band a CP-invariant phase of p/2, so no large strong phases in decay required

N(B0)-N(B0)

N(B0)+N(B0)

2pDmd 2tB

Wouter Verkerke, UCSB


A cp t from interference between mixing decay and decay

f = b

f = b

ACP(t) from interference between mixing+decay and decay

  • Time dependent CP asymmetry takes Ssin(Dmdt)+Ccos(Dmdt) form

  • C=0 means no CP violation in decay process

  • If C=0, coefficient S measures sine of mixing phase

mixing

decay

If only single real decay amplitude contributes

Wouter Verkerke, UCSB


Ckm angle measurements from b d decays

CKM Angle measurements from Bd decays

  • Sources of phases in Bd amplitudes*

  • The standard techniques for the angles:

bu

*In Wolfenstein phase convention.

td

B0 mixing + single bu decay

The distinction between a and gmeasurements is in the technique.

B0 mixing + single bc decay

Interfere bc and bu in B± decay.

Wouter Verkerke, UCSB


The pep ii b factory specifications

The PEP-II B factory – specifications

  • Produces B0B0 and B+B- pairs via Y(4s) resonance (10.58 GeV)

  • Asymmetric beam energies

    • Low energy beam 3.1 GeV

    • High energy beam 9.0 GeV

  • Boost separates B and B and allows measurement of B0 life times

  • Clean environment

    • ~28% of all hadronic interactions is BB

(4S)

BB threshold

Wouter Verkerke, UCSB


The pep ii b factory performance

Operates with 1600 bunches

Beam currents of 1-2 amps!

Continuous ‘trickle’ injection

Reduces data taking interruption for ‘top offs’

High luminosity

6.6x1033 cm-2s-1

~7 BB pairs per second

~135 M BB pairs since day 1.

Daily delivered luminosity still increasing

Projected luminosity milestone

500M BB pairs by fall 2006.

The PEP-II B factory – performance

Wouter Verkerke, UCSB


The babar experiment

The BaBar experiment

  • Outstanding K ID

  • Precision tracking (Dt measurement)

  • High resolution calorimeter

  • Data collection efficiency >95%

Electromagnetic

Calorimeter (EMC)

1.5 T Solenoid

Detector for

Internally reflected

Cherenkov radiation

(DIRC)

SVT: 5 layers double-sided Si.

DCH: 40 layers in 10 super-

layers, axial and stereo.

DIRC: Array of precisely

machined quartz bars. .

EMC: Crystal calorimeter (CsI(Tl))

Very good energy resolution.

Electron ID, p0 and g reco.

IFR: Layers of RPCs within iron.

Muon and neutral hadron (KL)

Drift chamber (DCH)

Instrumented

Flux Return (IFR)

Silicon Vertex

Detector (SVT)

Wouter Verkerke, UCSB


Silicon vertex detector

Silicon Vertex Detector

Readout

chips

Beam bending magnets

Beam pipe

Layer 1,2

Layer 3

Layer 4

Layer 5

Wouter Verkerke, UCSB


Erenkov particle identification system

Čerenkov Particle Identification system

  • Čerenkov light in quartz

    • Transmitted by internal reflection

    • Rings projected in standoff box

    • Thin (in X0) in detection volume, yet precise…

Wouter Verkerke, UCSB


Selecting b decays for cp analysis

DE

mes>5.27 GeV

N= 1506

Purity = 92%

mes

mes (GeV)

Selecting B decays for CP analysis

  • Exploit kinematic constraints from beam energies

    • Beam energy substituted mass has better resolution than invariant mass

    • Sufficient for relatively abundant & clean modes

(mES) 3 MeV

s(DE)  15 MeV

2

Wouter Verkerke, UCSB


Measuring time dependent cp asymmetries

Measuring (time dependent) CP asymmetries

  • B0B0 system from Y(4s) evolves as coherent system

    • All time dependent asymmetries integrate to zero!

      • Need to explicitly measure time dependence

    • B0 mesons guaranteed to have opposite flavor at time of 1st decay

      • Can use ‘other B0’ to tag flavor of B0CP at t=0

Vertexing

Tag-side vertexing

~95%

efficient

B-Flavor Tagging

sz170 mm

sz70 mm

Dt=1.6 ps  Dz 250 mm

Exclusive B Meson Reconstruction

Wouter Verkerke, UCSB

Dz/gbc


Flavor tagging

Flavor tagging

Determine flavor of Btag BCP(Dt=0)from partial decay products

Leptons : Cleanest tag. Correct >95%

Full tagging algorithm combines all in neural network

Four categories based on particle content and NN output.

Tagging performance

e-

e+

W-

W+

n

n

b

b

c

c

Kaons : Second best. Correct 80-90%

efficiency

mistake rate

W-

W+

c

c

K-

s

s

b

K+

b

W-

u

u

= 28%

W+

d

d

Wouter Verkerke, UCSB


Putting it all together sin 2 b from b 0 j y k s

B0(Dt)

B0(Dt)

ACP(Dt) = Ssin(DmdDt)+Ccos(DmdDt)

sin2b

Dsin2b

Putting it all together: sin(2b) from B0 J/y KS

  • Effect of detector imperfections

    • Dilution of ACP amplitude due imperfect tagging

    • Blurring of ACP sine wave due to finite Dt resolution

  • Measured & Accounted for in simultaneously unbinned maximum likelihood fit to control samples

    • measures Dt resolution and mistag rates.

    • Propagates errors

Imperfect flavor tagging

Finite Dt resolution

 Actual sin2b result on 88 fb-1

Wouter Verkerke, UCSB

Dt

Dt


B factory flagship measurement sin2 b from j y k s

*

Vcb

c

b

J/Y

f = 0

W+

c

B0

Vcs

s

f = b

Ks

d

d

f = b

B-factory ‘flagship’ measurement: sin2b from J/y KS

  • Interference between mixing and single real decay

    • Interfering amplitudes of comparable magnitude  the observable asymmetry is large (ACP of order 1)

  • Extraordinarily clean theory prediction (~1% level)

    • Single real decay amplitude  all hadronic uncertainty cancel

    • ACP(t) = sin(2b) sin(Dmd t)

  • Experimentally easy

    • ‘Large’ branching fraction O(10-4)

    • Clear signature (J/y l+l-and KS p+p-)

Decay

B0 Mixing……followed by………Decay

d

Ks

s

Vcs

*

c

W+

J/Y

c

f = 0

Vcb

Wouter Verkerke, UCSB


Golden measurement of sin2 b

Combined result (88 fb-1, 2001)

sin2b = 0.741  0.067  0.034

|l| = 0.948  0.051  0.030

(stat)

(syst)

sin2b = 0.76  0.074

‘Golden’ measurement of sin2b

B0 (cc) KS (CP=-1)

No evidence for cos(DmDt) term

sin2b = 0.72  0.16

B0 (cc) KL (CP=+1)

Wouter Verkerke, UCSB


Standard model interpretation

r = r(1-l2/2)

h = h(1-l2/2)

Standard Model interpretation

Constraints on the apex of the Unitarity Triangle.

h

r

Wouter Verkerke, UCSB

Method as in Höcker et al, Eur.Phys.J.C21:225-259,2001


Standard model interpretation1

Standard Model interpretation

4-fold ambiguity because we measure sin(2b), not b

One solution for b is very consistent with the other constraints.

2

1

Latest results including the Belle experiment.

h

  • The CKM model for CP

  • violation has passed its first precision test!

3

There is still room for improvement:

measurement is statistics dominated

Summer ’04 data  2-3 x 88fb-1

4

r

Wouter Verkerke, UCSB

Method as in Höcker et al, Eur.Phys.J.C21:225-259,2001


B factory measurements of sin2 b

B-factory measurements of sin2b

  • Going beyond the ‘golden’ modes

    • Consistency requires S=sin2b, C=0for all B0 decay modes for whichthe weak phase is zero.

    • Decay modes dominated by the bs penguin may meet these criteria

    • Measure ACP(t) from interference between mixing + bs decayand bs decay

  • Loop diagrams are sensitive to contributions from new physics

    • Look for deviations of S=sin2b

f=0

f=0

f=???

f=???

Wouter Verkerke, UCSB


Standard model expectation for sin 2 b from b s penguins

u/

u/

Standard model expectation for sin(2b) from bs penguins

I

Experimentally best modes:

B0fK0

B0h’K0

B0p0K0

(I, II & III)

(II & III)

f = g / 0

(I)

  • SM contributions that spoil S = sin2b

    • u-quark penguin (weak phase = g!) but relative CKM factor of ~0.02

    • u-quark tree (different phase)

II

f = g / 0

these limits

will improve

with additional

data

f = g

III

*Grossman, Ligeti, Nir, Quinn. PRD 68, 015004 (2003) and Gronau, Grossman, Rosner hep-ph/0310020


B s penguin measurements

bs penguin measurements

  • Experimentally more difficult

    • Branching fractions smaller, more irreducible background

B0 fKS

B0 KSp0

B0 h’KS

Wouter Verkerke, UCSB


Sin2 b from b s penguin measurements

sin2b from bs penguin measurements

h’Ks

BaBar 0.02  0.34  0.03

fKs

BaBar 0.45  0.43  0.07

p0Ks

BaBar 0.48 (+0.38)  0.11

–0.47

bs penguin average

Babar 0.27  0.22

Wouter Verkerke, UCSB

sin2b from B0 (cc) KS


Sin2 b from b s penguin measurements1

sin2b from bs penguin measurements

(My naïve averages)

h’Ks

BaBar 0.02  0.34  0.03

Belle0.43  0.27  0.05

Ave0.27  0.21

fKs

BaBar 0.45  0.43  0.07

Belle –0.96  0.50 (+0.09)

Ave–0.14  0.33

–0.11

p0Ks

Babar 0.48 (+0.38)  0.11

–0.47

K+K-Ks non-resonant

Belle 0.51  0.26  0.05 (+0.18)

–0.00

bs penguin average

Babar and Belle 0.27  0.15

Wouter Verkerke, UCSB

sin2b from B0 (cc) KS


Sin2 b b s penguin modes

sin2b : bs penguin modes

  • Current naïve world averages

    S = 0.27 ± 0.15 (~3s below J/yKs S = 0.74 ± 0.05).

    C = 0.10 ± 0.09

  • Still very early in the game

    • Measurements are statistics limited. Errors smaller by factor 2 in 2-3 years.

    • Standard Model pollution limits from SU(3) analysis will also improve with more data.

Wouter Verkerke, UCSB


The angle a from b pp

f = b

f = b

The angle a from B  pp

  • Determination of a: Observe ACP(t) of B0 CP eigenstate decay dominated by bu

    • Interference between mixing+bu decay and bu decay

    • Textbook example is B0 p+p-.

  • If the above bu tree diagram dominates the decay

    ACP(t)=sin(2a)sin(DmdDt).

B0 Mixing

bu decay

Vub

f = g

sin2a

Wouter Verkerke, UCSB


The angle a the penguin problem

The angle a - the penguin problem

  • Turns out the dominant tree assumption for p+p- is bad.

    • There exists a penguin diagram for the decay as well

    • Magnitude of penguin can be estimated from B  K+p-(dominated by SU(3) variation of this penguin)

    • Penguin amplitude is large, contribution to B  p+p- could be ~30%!

  • Including the penguin component (P) in l

  • Coefficients from time-dependent analysis

tree decay

penguin decay

s

Vtd/Vts

/ K+

Vub

f = 0

f = 0

f = g

Ratio of amplitudes |P/T|and strong phase difference dcan not be reliably calculated

Unknown phase shift

Wouter Verkerke, UCSB


Disentangling the penguin determining 2 k

Disentangling the penguin: determining 2k

  • Gronau & London: Use isospin relations

    • Measure all isospin variations of B  pp

    • B0 p+p- , B0  p+p-, B0  p0p0 , B0  p0p0 B-  p-p0 = B+  p+p0

    • Weak phase offset 2k can bederived from isospin triangles

  • Complicated…

2k

-

Wouter Verkerke, UCSB


Disentangling the penguin the grossman quinn bound

Disentangling the penguin: the Grossman-Quinn bound

  • Easy alternative to isospin: Grossman-Quinn bound

    • Look at isospin triangles and construct upper limit on k

    • Minimum required input: BF(B pp0) and limit on BF(B0 p0p0)

    • Works best if B0 p0p0 is small

    • Experimental advantage: no flavor tagging in Bp0p0

  • Measure B0  p0p0!

‘~10-5’

‘~10-6’

Wouter Verkerke, UCSB


The grossman quinn bound on k for b 0 pp

the Grossman-Quinn bound on k for B0 pp

  • B0 p0p0 is observed! (4.2s)

  • GQ Bound using world averages

    • p0p0: (1.9±0.5)x10-6

    • p±p0: (5.3±0.8)x10-6

  • p0p0 large, thus GQ bound not very constraining

    • Isospin analysis required for p0p0!

Plots are after cut on signal probability ratio not including variable shown, optimized with S/sqrt(S+B) .

[BELLE: (1.7±0.6±0.2)x10-6, 3.4s]

Wouter Verkerke, UCSB


Alternatives to b pp for determination of a

Alternatives to B  pp for determination of a

  • There are other final states of bu tree diagram, e.g.

    • B  rp (Dalitz analysis required)

    • B  rr (Vector-vector  multiple amplitudes)

  • B  r+r- analysis

    • 3 helicity amplitudes: Longitudinal (CP-even), 2 transverse (mixed CP)

    • Looks intractable, but entirely longitudinally polarized*!

    • r+r- is basically a CP-even state with same formalism as p+p-.

Wouter Verkerke, UCSB

*As predicted by G.Kramer, W.F.Palmer, PRD 45, 193 (1992). R.Aleksan et al., PLB 356, 95 (1995).


The grossman quinn bound for b 0 rr

the Grossman-Quinn bound for B0 rr

  • The Grossman-Quinn bound for B0 rr

(BaBar)

(Belle)

(assuming full longitudinal polarization)

Wouter Verkerke, UCSB


Alpha summary

Alpha summary

  • The pp system: large penguin pollution

    • We have seen B0p0p0!

    • Current GQ bound:

    • Full isospin analysis required!

  • The rr system: small penguin pollution

    • Polarization is fully longitudinal (as predicted).

    • Current GQ bound:

    • Bound may improve as additional data becomes available

    • Time-dependent r+r- results (measures sin(2a+2k)) coming soon.

  • There are more techniques than pp and rr

    • e.g. Dalitz analysis of rp

Wouter Verkerke, UCSB


The angle g

The angle g

  • Measuring g = Measuring the phase of the Vub

    • Main problem: Vub is very small: O(l3)

    • Either decay rate or observable asymmetry is always very small.

  • Conventional wisdom: measuring g at B factories is difficult/impossible.

    • Gamma is the least constrained angle of the Unitarity Triangle

  • Current attitude: we should try.

    • There are new ideas to measure g (Dalitz decays, 3-body decays,…)

    • New experimental data suggest color suppression is less severe, which eases small rate/asymmetry problem somewhat

    • B-Factories produce more luminosity than expected(BaBar & Belle approaching O(200) fb-1 by Summer ’04 time )

Wouter Verkerke, UCSB


The angle g b dk

The angle g: B  DK

  • Strategy I: interfere bu and bc decay amplitudes

    • D0/D0 mustdecay to common final stateto interfere

  • Ratio of decay B amplitudes  rb is small: O(10-1)

  • rb isnot well measured, but important

    • rb large  more interference  more sensitivity to g

f=g

color

suppression

f=0

Ru is the left side of the Unitarity Triangle (~0.4).

FCS is (color) suppression factor([0.2-0.5], naively1/3)

Wouter Verkerke, UCSB


G from b dk two approaches

g from B  DK – Two approaches

  • Approach I: D0/D0 decay to common CP eigenstate

    • ‘Gronau, London & Wyler’

    • D0/D0 decay rate same

  • Approach II: D0/D0 decay to common flavor eigenstate

    • ‘Atwood, Dunietz & Soni’

    • Use D0/D0 decay rate asymmetry to compensate B decay asymmetry`

  • Complementary in sensitivity

    • GLW:large BF: O(1±rb), small ACP: O(rb)

    • ADS:small BF: O(rb2),large ACP: O(1)

Branching fractionssmall (0.1%-1%)

CKM favored

Doubly Cabibbo suppressed (by factor O(100))

Wouter Verkerke, UCSB


B dk observables gronau london wyler

B  DK Observables – Gronau-London-Wyler

  • There are more observables sensitive to g than ACP

    • Absolute decay rate also sensitive to g, but hard to calculatedue to hadronic uncertainties

    • GLW: measure ratio of branchingfractions: hadronic uncertainties cancel!

    • Experimental bonus: many systematic uncertainties cancel as well

    • Bottom line: 2 observables each for CP+ and CP- decays

  • 3 independent observables (R+, R-, A+=-A-), 3 unknowns (rb, db, g)

Wouter Verkerke, UCSB


B dk glw results

B  DK : GLW results

GLW method: large BF, small ACP

  • Result for B-  D0 K- in 115 fb-1

  • Results for CP-odd modesin progress (R-, A-)

D0p-

background

Wouter Verkerke, UCSB


B dk the atwood dunietz soni method

B  DK : The Atwood-Dunietz-Soni method

  • Two observables, similar to GLW technique

    • Ratio of branching fractions and ACP

  • D0 K+p-: 2 observables (A, R), 3 unknowns (rb, db+dd, g)

    • Insufficient information to solve for g

    • Can add other D0 decay modes, e.g. D0 K+p-p0  4 observables (2xA, 2xR), 4 unknowns (rb, db+dDKp, db+dDKpp0, g)

  • Expected BF is ~510-7 – very hard!

    • Expect observable O(10) events in 100M BB events

    • Unknown values of g, rb, db add O(10) uncertainty of BF estimate

    • Measurement not attempted until now

Wouter Verkerke, UCSB


G from atwood dunietz soni method b k p d0 k results

g from Atwood-Dunietz-Soni method: B- [K+p-]D0 K- : results

MC yield prediction with BF=7x10-5: 12 evts

ADS method: small BF, large ACP

  • Newly developed background suppression techniques give us sensitivity in BF = O(10-7) range BF 5x10-7 ~10 events

  • But we don’t see a signal!

    • Destructive interference, rb is small, or just unlucky?

  • Cannot constrain g with this measurement…

    • But BF proportional to rb2 results sets upper limit on rb

Yield in 115 fb-1 of data:1.1  3.0 evts

No assumptions: rb < 0.22 (90% C.L.)

  • from CKM fit : rb < 0.19 (90% C.L.)

    (95% C.I. region)

Wouter Verkerke, UCSB


B dk prospects for b factories at 500 fb 1

B  DK : prospects for B-factories at 500 fb-1

  • Combine information ong from various sources

  • Example study

    • Assume g=75o, db=30o, dd=15o

    • Consider various scenarios

      • GLW alone

g=75o, db=30o, dd=15o

Dc2

rb=0.3

3s

2s

GLW

1s

g

Wouter Verkerke, UCSB


B dk prospects for b factories at 500 fb 11

B  DK : prospects for B-factories at 500 fb-1

  • Combine information ong from various sources

  • Scenarios

    • GLW alone

    • GLW+ADS(Kp)

    • GLW+ADS(Kp)+dd from CLEO-c

  • ADS/GLW combination powerful

  • There are additional information not usedin this study, e.g.

    • GLW: D*0K,D0K*,D*0K*

    • ADS: Kpp0,K3p

    • sin(2b+g) from D*p, D0K0, DKp,…

g=75o, db=30o, dd=15o

Dc2

rb=0.3

3s

GLW+ADS+CLEO-c

GLW+ADS

2s

11o

GLW

1s

g

Wouter Verkerke, UCSB


B dk prospects for b factories at 500 fb 12

B  DK : prospects for B-factories at 500 fb-1

  • Combine information ong from various sources

  • rb is critical parameter

g=75o, db=30o, dd=15o

3s

rb=0.1

2s

67o

1s

3s

rb=0.2

2s

D2

1s

23o

3s

rb=0.3

2s

11o

1s

g

Wouter Verkerke, UCSB


Gamma summary

Gamma summary

  • The B  DK program is underway

    • Measurements for GLW methods in progress (B  D(*)0 K(*)-)

    • First measurement of ADS method (B  [K+p-]K-)

    • ADS and GLW techniques powerful when combined

    • Final results depends strongly on rb

  • Other g methods in progress as well

    • Dalitz analyses of B-  D0(KSp+p-)K-, B  DKp

    • Time dependent analysis of B  D*p- (mixing + Vub decay)

      • |sin(2b+g)|>0.57 (95% C.L.))

    • Analysis of B0  D(*)0 K(*)0

  • There is no ‘golden’ mode to measure g

    • All techniques are difficult and to 1st order equally sensitive.

    • Combine all the measurements and hope for the best

Wouter Verkerke, UCSB


Concluding remarks

Concluding remarks

  • The CKM model for CP violation passed it’s first test (sin2b).

    • Future measurements of sin2b from B0  (cc)KS will continue improve constraints on apex of unitarity triangle

  • The bs penguin measurement of sin2b offers a window to new physics.

    • Another 2-3 years worth of data will clarify current 3s discrepancy

  • We are cautiously optimistic that we can measure a now that B  rr decay turns out have little penguin pollution

  • Measurement of g just starting. Success depends on many unknowns…

  • BaBar is projected to double its current dataset by 2006

Wouter Verkerke, UCSB


  • Login