Measurements related to the CKM angle α from BABARmoriond.in2p3.fr/EW/2004/transparencies/5_Friday/5_2...Measurements related to the CKM angle α from BABAR LYDIA ROOS LPNHE-Paris

Measurements related to the CKM angle α from BABARLYDIA ROOSLPNHE-Paris

Rencontres de MoriondEW04

B → ππB → ρπB → ρρ

will cover:

α from B → hh (h=π,ρ)

Tree diagram:Tree diagram:

ubV ∗∗∗∗

d

Penguin diagram:Penguin diagram:

ααα

αλ λ

−

+

−= = =

−22

1

1eff

i

iihh i

P eq A Te ePp A eT

α + β + γ = π

β−= 2iqe

p

,i i

i i

A e T e P

A e T e P

γ β

γ β

+ −

− +

= +

= +

0 0

0 0

( ( ) ) ( ( ) )( )

( ( ) ) ( ( ) )

sin( ) cos( )

CP

hh hh

N B t h h N B t h hA t

N B t h h N B t h h

S mt C mt

+ − + −

+ − + −

→ − →=→ + →

= ∆ − ∆ 2

2

1

1hh

hh

hh

Cλλ

−=

+2

2 Im

1hh

hh

hh

Sλ

λ=

+

π ρ,+ ++ ++ ++ +

tdV

d ++++ππ ρ,+ ++ ++ ++ +

π ρ,− −− −− −− −

π ρ,− −− −− −− −

In the usual phase convention:

g

3

B0

B0

hhhh+h-

A+-

A+-

Time-dependent CP asymmetriesin B → ρπ

ππππ +

ρρρρ -

d

S: CPV in decay/mixing interferencesC: direct CPV

Usual CP parameters

h++++

( ) ( ) ( ) ( )( )+ −Γ → ∝ ± − ± ∆ ∆ ∆ + ± ∆ ∆ ∆0 1 1 sin( ) cos( )CPB h h A S S m t C C m t( ) ( ) ( ) ( )( )ρ π±Γ → ∝ ± − ± ∆ ∆ ∆ + ± ∆ ∆ ∆m0 1 1 sin( ) cos( )CPB A S S m t C C m t( ) ( ) ( ) ( )( )ρ π±Γ → ∝ ± − ± ∆ ∆ ∆ + ± ∆ ∆ ∆m0 1 1 sin( ) cos( )CPB A S S m t C C m t

∆S: from strong phase δ=arg(A-+/A+-)∆C: W→ρρρρ vs. spectactor→ρρρρ asymmetry

ACP: ρρρρ++++ππππ−−−− vs. ρρρρ−−−−ππππ++++ asymmetry Direct CPV

No CPVDILUTION factors

h−−−−

π++++

d

B0

B0

ρρρρ+ππππ-A+-

A-+

ρρρρ-ππππ+

A-+

A+-≠≠≠≠

ρ++++

ρ−−−−π−−−−

Extraction of α: Isospin Analysis

0 000

2 2

A A A AA

+− −+ + ++− −+ + ++− −+ + ++− −+ + ++ ++ ++ ++ ++ =+ =+ =+ =

B → hh': 2 pentagonal relations between amplitudes from strong isospin symmetry [LNQS]:

0 000

2 2

A A A AA

+− −+ + ++− −+ + ++− −+ + ++− −+ + ++ ++ ++ ++ ++ =+ =+ =+ =

12 unknowns and 13 observables : in principle, solvable

LNQS: Lipkin, Nir, Quinn, Snyder, PRD44, 2193 (1991)

00 0 0 00 2

2 0 2

1 2 / ( 2 2 )cos(2 2 )

1 4 1eff

hh hh

B B B B B

C B B Cα α

+ +− +

+− +

− − +− ≥ +− −

If C00 is not measured, one has the bound [GLSS]:

GL: Gronau, London, Phys.Rev.LettD65:3381,1990 GLSS: G,L,Sinha,Sinha, Phys.Lett.B514:315- 320,2001

6 unknowns and 7 observables (or 6: no measure ofS00 in B → ππ)

B → hh: 2 triangular relations [GL]

00 0/ 2A A A+− ++− ++− ++− ++ =+ =+ =+ = 00 0/ 2A A A+− ++− ++− ++− ++ =+ =+ =+ =+ += +0 0 ( )EWA A O Pwith

Common experimental aspectsB candidate mass and energycontinuum background

e- e+ e- e+

§Kinematical variables: cos(PB,z), cos(TB,z)

Combined using Fisher or NN

( )θ∉ ∉

= =∑ ∑2

0 2 , L , L cosBi i T i

i B i B

p p

§Topological variables in CMS, e.g.

θ , BT i

BB qq

Moriond EW04 LYDIA ROOS LPNHE-Paris 6

more rejection of B background Particle Identification

Common experimental aspects

All channels but π+π− suffer fromB background. Useful variables are:§∆E§ρ mass, helicity angle

B0 → ρ+ π−

Unbinned likelihood fitLikelihood function includes time dependence

Moriond EW04 LYDIA ROOS LPNHE-Paris 7

B0 → h+ h- (h=π,K)

π ππ

+ −

+ −

+ −

→ ± ±→ ± ±

→

0 -6

0 -6

0 -6

( ) = (4.7 0.6 0.2) 10

( ) = (17.9 0.9 0.6) 10

( ) < 0.6 10 (90% CL)

Br B

Br B K

Br B K K

π

ππ

ππ

= − ± ±= − ± ±

± ±

0.40 0.22 0.03

0.19 0.19 0.05

= -0.107 0.041 0.013KCP

S

C

A

81 fb-1

113 fb-10B

0B

all

bkg

PRL 89 281802 (2002); PRELIMINARY LP03

Moriond EW04 LYDIA ROOS LPNHE-Paris 8

B± → π±π0 and B0 → π0π0

Yield: 46 ± 13 ± 3

Significance: 4.2σ

113 fb-181 fb-1

0 1.0 60.9

0 1.2 61.1

BR( ) (5.5 0.6)10

BR( ) (12.8 1.0)10K

π ππ

± + −−

± + −−

= ±

= ±0 0 6BR( ) (2.1 0.6 0.3)10π π −= ± ±

PRL 91 021801 (2003); PRL 91 241801 (2003)

0π π ±

0 0π π

B0 → ρ+ π−

ρπ

ρπ

ρπ

ρπ

ρπ

= − ± ±

= ± ±

∆ = ± ±

∆ = ± ±

± ±

0.13 0.18 0.04

0.35 0.13 0.05

0.33 0.18 0.03

0.20 0.13 0.05

= -0.114 0.062 0.027CP

S

C

S

C

A

113 fb-1

0B

0B

PRL 91 201802 (2003)

Significance for direct CPV: 2.5σ

• Isospin analysis needs ~10 ab-1 to disentangle multiple solutions;• More promising: perform full Dalitz plot analysis;• Powerful but model-dependent constraint from QCD FA [BN]: σ(α) ∼9°

Quasi two-body approach:

BN: Beneke, Neubert, Nucl. Phys. B675(2003) 333

B0 → ρ+ ρ−

Three helicity states:longitudinal (CP+) and tranverse (CP+/-)

Mis-reconstructed signal events:39% (longitudinal), 16% (transverse)

B background in signal region:§~350 B0, B± → charm;§ charmless B modes (~65 events), mainly:

ρ+π0, a1ρ, a1π, ρ+ρ0,(higher K res)π

= − ± ±

= − ± ±

0.42 0.42 0.14

0.17 0.27 0.14long stat syst

long stat syst

S

C

ρ ρ −

+−

+ − = ± ±

= ±

6

0.040.03 ( )

( ) (30 4 5 )10

0.99 0.03

stat syst

long (stat) syst

BR

f

81 fb-1

Submitted to PRL

θcos H

New result on B0 → ρ+ ρ−

113 fb-1

0B

0B

= − ± ±

= − ± ±

0.19 0.33 0.11

0.23 0.24 0.14long stat syst

long stat syst

S

C

§Main systematics: CPV in B bkg §Detailed study of B background: 209 B decay modes simulated

§ Isospin analysis: interference, NR contributions, I=1 amplitudesneglected

PRELIMINARY

α = ± ± ± o(96 10 4 13 )stat syst peng

More on α from B→ππ,ρρ

Other ingredients in ρρ isospin analysis: (BABAR & Belle),ρ ρ

ρ ρ

−

+−

+ = ±+ =

6

0.0490.065

0

0

( ) (26.4 6.4)10

( ) 0.962long

BR

f

ρ ρ

ρ ρ

+ −−= ±

=

0.72 60.60

0 0

0 0

( ) (0.62 0.12)10

( ) 1.0long

BR

f(BABAR & Belle),Slide from the CKMfitter group incorporating BABAR CP asymmetries and other BABAR & Belle results

(BABAR)(assumed)

BABAR: PRL 91 171802; Belle: PRL 91 221801

(no ππ,ρρ)

Moriond EW04 LYDIA ROOS LPNHE-Paris 13

ConclusionB → ππ: evidence/observation of all decay modes.

No significant constraint on α with present data.B → ρπ: quasi 2-body asymmetries measured.

Next step is the full Dalitz plot analysis.B0 → ρ+ρ− CP asymmetries

§ Constraint on α in perfect agreement with the Standard Fit;

§ low penguin pollution;§ if BR(ρ0ρ0) not too small, measure not only Cρ0ρ0 but also Sρ0ρ0

= − ± ±

= − ± ±

0.19 0.33 0.11

0.23 0.24 0.14long stat syst

long stat syst

S

C

= − ± ±

= − ± ±

0.42 0.42 0.14

0.17 0.27 0.14long stat syst

long stat syst

S

C

81fb-1 submitted 113 fb-1 preliminary

α = ± ± ± o(96 10 4 13 )stat syst peng