Measurements of and future projections

Fabrizio BianchiUniversity of Torino and INFN-Torino

Beauty 2006 The XI International Conference on B-Physics at

Hadron Machines

2

Outline Introduction to the measurement of

Results from the B-factories: B ±

±

Summary and outlook

Will not cover expectations at LHC and Super B-Factories

See talks of P. Robbe and A. Bevan

3

Measuring

)(cos)(sin))(())((

))(())(()(

00

00

tmCtmSftBftB

ftBftBtA

dd BBCP

0

)2sin(

222

C

S

eeeA

A

p

q iii

Access to from the interference of a b→u decay () with B0B0 mixing ()

sin

)2sin(1 2

C

CS eff

ii

iii

eePT

eePTe

2

Inc. penguin contribution

4

From eff to : Isospin Analysis

0hhB

)(~

)(

)(~

)(

)(~

)(

00000

00000

00

00

0

0

hhBAA

hhBAA

hhBAA

hhBAA

hhBAA

hhBAA

Gronau and London, Phys. Rev. Lett. 65, 3381 (1990)

Neglecting EW Penguins: is a pure tree mode.The triangles share a common side.

Assume SU(2) symmetry among amplitudes

00 ~ AA0hhB

5

Time Dependent Analysis Outline

Fully reconstruct the B decaying to a CP eigenstate.

Tag the flavor of the other B. Mis-tag probability measured in Bflav sample.

Measure t.

Extract S and C with a ML fit on a signal enriched sample. Signal PDF from MC. Background PDF from MC or sidebands

6

Variables used in the ML fit

2*2*BbeamES pEm **

beamB EEE

signal signal

background background

Event TopologyCombine variables in F or N

PID info: DIRC + dE/dX (BaBar) Aerogel + dE/dX (Belle)

t

7

:results (preliminary)

0B

Background Signal

mE

S

mE

S

E

E

347 million BB

0B

sPlotN = 675±42

hep-ex/0607106

B0tag

B0tag

8

:results (preliminary)

535 million BB

0B

N = 1464±65

hep-ex/0608035

9

:results (preliminary) 0B

C = - 0.55 ± 0.08 ± 0.05S= - 0.61 ± 0.10 ± 0.04

C = - 0.16 ± 0.11 ± 0.03S = - 0.53 ± 0.14 ± 0.02

(S, C) = (0.0, 0.0) excluded at 3.6

Observation of Direct CPV at 5.5 Observation of mixing-induced CPV at 5.6

347 million BB

535 million BB

2.3 discrepancy

C =−A

Belle

BaBar

Average

10

(preliminary)0000 , B

347 million BB

hep-ex/0607106

N = 140 ± 25N± = 572 ± 53

0 B

11

constraint from B

No stringent constraintfrom system alone need and

|| < 41o at 90% C.L.

Frequentist interpretation: use only the B→branching fractions and isospin-triangle relations.

eff

1-

C.L

.1-

C.L

.

12

The analysis

Worse than at first sight: V V final state. Mixture of CP = +1 and 1: need to

know each fraction

However: ~100% longitudinally polarized (~pure CP-even

state) no need for elaborate angular analysis

Branching fraction for B0 is larger than

Branching fraction for B0 is small (~1.1x10-6) small penguin pollution

0B

13

results (preliminary)

0B

347 million BB

hep-ex/0607098

14

results

0B

09.041.008.0

09.030.000.0

long

long

S

C68.2

6.2 10)8.38.22( BR

275 million BB

PRL 96, 171801 (2006)

030.0941.0 034.0040.0

Lf

0B

N = 194±32

15

results (preliminary)

0B

16

results (preliminary)

0 B

232 million BB

hep-ex/0607092

N =390 ± 49

17

results (preliminary)

000 B

347 million BB

hep-ex/0607097

N = 98 ± 32 ± 22

3.0 evidence

18

constraint from B[71, 105]o

at 68.3% C.L.

Frequentist interpretation: use only the B→ρρbranching fractions, polarization fractions and isospin-triangle relations.

First evidence of B→00

Constraint on is less stringent

PRL 96, 171801 (2006)hep-ex/0607098

Use BR(B->00)<1.1 X 10-6

19

The Dalitz analysis00 )(B

A. Snyder and H. Quinn, Phys. Rev. D, 48, 2139 (1993)

B0

B0

Monte Carlo

(1450) and (1700) are included

Interference provides information on strong phase difference

Time-dependent Dalitz-plot analysis assuming isospin simmetry.

26 coefficients of the bilinear form factor terms occurring in the decay rate are measured with a UML fit. Physically relevant quantities are derived from subsequent fits to these coefficients.

20

analysis (preliminary) 00 )(B

hep-ex/0608002347 million BB

m’ and ’ are thetransformed Dalitz variables

21

analysis (preliminary)00 )(B

hep-ex/0609003449 million BB

mass

helicity

Dalitz + Isospin (pentagon) analysis 26(Dalitz) + 5(Br(), Br(+0), Br(0+), A(+0), and A(0+))

SignalSCFBB bkgcontinuum

22

constraint from (preliminary)

00 )(B

[0,8]o U [60,95]o U[129,180]o

at 68.3% C.L.

(deg) (deg)

1-

C.L

.

1-

C.L

.

23

constraints

B-Factories = [ 93 ] º +11-9

Global Fit = [ 98 ] º +5-19

Belle result is not included.It will weakens the suppressionof solutions around 0o and 180o.

Nice agreement B-Factories = [92 ± 7]o (SM Solution)

Global Fit = [93 ± 6]o

CKMfitter http://ckmfitter.in2p3.fr/UTfit http://utfit.dreamhosters.com/

B-Factories

Global Fit

24

Pending Issues

Discrepancy on C

Solutions at 0o and 180o should be (more) suppressed. Using nice suppression from BaBar, not from Belle.

Background modeling.

Interference with other resonances or non-resonant component in , modes.

Subtleties on statistical analysis with small statistics.

C = - 0.16 ± 0.11 ± 0.03

C = - 0.55 ± 0.08 ± 0.05

25

Uncertainties on extraction Possible contribution of EW penguin and isospin

breaking effect. EW penguin effect seems to be small (~2°). Other isospin breaking effect ~ O(1°).

[M.Gronau and J.Zupan PRD 71, 074017(2005)]

I=1 contribution due to finite width of mass ( mode).[A.Falk et al. PRD 69, 011502(R)]

Too small to be an issue at B-factories

26

Summary and Outlook The three modes are complementary.

Need to study them all.

Good agreement between the CKM fit ( determined by others) and direct measurements.

Still a lot to do. Refine previous analysis and exploit new ideas:

from B->a1 ? Constraint on from B0->+- and B+->K*0+

[M. Beneke et al., Phys. Lett. B638, 68(2006)] Doubling of statistics at the B-factories is much needed.

Looking forward to LHC and to a Super B-Factory.

Backup Slides

28

)(cos)(sin

))(())((

))(())(()(

00

00

tmCtmS

ftBftB

ftBftBtA

dCPdCP

CP

BfBf

CPphysCPphys

CPphysCPphysf

0B

0B

CPfCP

mixin

g

decay

0t

tCPfA

CPfA

CP

CP

CPCP

f

fff

A

A

pq

ηλ

CP eigenvalue i2e

Amplituderatio2

f

2f

f||1

||1C

CP

CPCP

2f

ff

||1

Im2S

CP

CPCP

Time Dependent CP Asymmetry

29

BABAR Detector

30

DIRC: Control samples for and

K

K

Projection for 2.5 < p < 3 GeV/c

* 0From ( )D KD

31

32

:results (preliminary) 0B

C = - 0.16 ± 0.11 ± 0.03S = - 0.53 ± 0.14 ± 0.02

(S, C) = (0.0, 0.0) excluded at 3.6

33

:results (preliminary) 0B

A = + 0.55 ± 0.08 ± 0.05S= - 0.61 ± 0.10 ± 0.04Observation of Direct CPV at 5.5

Observation of mixing-induced CPV at 5.6

34

constraint from B

35

constraint from B

36

formalism

)]cos(()()sin()(1[8

))(1())((/||

tmCCQtmSSQ

eAtB

tagtag

t

CP

CAC

CACAA

CAC

CACAA

CP

CPCP

CP

CPCP

)(1

)()()(

)(1

)()()(

S

Direct CP Violation

CP violation in the interference with and without B mixing.

00 )(B

37

parameters (prelim)00 )(B

38

Direct CP violation in 00 )(B

Significance for non-zero DCPV:BaBar: 3.0 Belle: 2.4