Experimental Overview of B Physics

11/18/2004 Paoti Chang

1

Experimental Overview of B Physics

Paoti Chang

National Taiwan University

2004/11/19

Mini-workshop on Flavor Physics


2

Introduction

• Bottom quark was discovered in 1977.

• Experiments tried to study B physics in the 80s/90s.

− Fixed Target Experiments Hard to trigger and dirty env. − e e U(4S) BB Productive (CLEO and ARGUS ) − e e Z/WW bb Good but limited by statistics − pp bb Leptons, secondary vertices (CDF)

Need luminosity; no

LHC, LHCb and BTeV in 21 centry


3

CP Violation

• CP: Ccharge conjugate; Pparity

CPV diff. prop. for matter and anti-matt.

• A tiny CP Violation was observed

in the Kaon system (1964).

Obs. another CPV evidence 35 years later. • In 1973, Kobayashi & Masakawa proposed six quark flavor.


4

KM Mechanism• CPV arises from a complex phase in the quark mixing matrix.

b

s

d

VVV

VVV

VVV

b

s

d

tbtstd

cbcscd

ubusud

'

'

'

=


5

Motivation• CPV may be large in the B meson system. (B

J/S)

• Is CP violation only due to a single weak phase?• Is there any new interaction beyond the standard

model?• Measure the three angels and size of the triangle.

• Measure B meson property.

• Rare B decays provide a

rich ground to understand

B decays.

• It’s useful to search for

new physics.


6

CP Violation in B Meson Decays

Indirect CP Violation (Mixing + Tree interference)


7

Mixing induced CPV Asymmetry

In Hadron collider experiments, t is the B0 decay time.

Measure the primary vertex (collision point) and decay vertex

In S) experiments, t is the decay time differences between

B0 and B0. How to measure t?


8

Asymmetric e eCollider

Piermaria Oddone


9

Indirect CPV illustration

• The difference in the t distributions indicates ICPV.

• sin21 corresponds to the amplitude of ACP.

• If the area of the red and blue are different DCPV.• Search for DCPV in B decays to flavor specific states.


10

Requirements to do B physics

• Lots of Bs B factory

• Able to reconstruct B vertices Silicon D.

• Good Particle identification

• Able to detect photons and electrons

CsI(Tl) detector

• Good coverage and able to measure KL

• Fast DAQ and lots of CPU and storages.


11

The PEPII Collider (magnetic separation)

On resonance:

221 fb-1

9 x 3.0 GeV; L=(9.2 x 1033)/cm2/sec

Int(L dt)=

244 fb-1


12

The KEKB Collider (8 x 3.5 GeV, X angle)

World record:

L=(1.4 x1034)/cm2/sec

Int(L dt)= 323 fb-1

On-resonance 295 fb-1


13

Belle Collaboration

Masashi Hazumi (KEK)

~300 members

Masashi Hazumi (KEK)

~54 Institutes


14

BaBar Detector

Cherenkov Detector (DIRC)[144 quartz bars, 11000 PMTs]

Silicon Vertex Tracker (SVT)[5 layers]

Instrumented Flux Return (IFR) [Iron interleaved with RPCs].

CsI(Tl) Calorimeter (EMC)[6580 crystals].

Superconducting Coil (1.5T)

Drift Chamber [40 stereo lyrs](DCH)

e- (9 GeV)

e+ (3 GeV)


15

Belle Detector

/ KL detection 14/15 lyr. RPC+Fe

CsI(Tl) 16X0

Aerogel Cherenkov cnt. n=1.015~1.030

Si vtx. det. 3 lyr. DSSD

TOF counter

SC solenoid1.5T

8GeV e

3.5GeV e

EFC


16

B Meson Reconstruction

B candidates are identified by the beam constrained mass(Mb)

22Bbeamb PE=M

beamB EE=ΔE

qqee

BBSee

)4(


17

Flavor Tagging Algorithm

r =(1-2w)MC

q = Btag

q = Btag


18

Vertex Reconstruction

Validated by B lifetimes

B0 = 1.55 0.02ps B+ = 1.64 0.03psPDG: 1.55 0.03ps PDG: 1.65 0.03ps

BD*l


19

Event by Event Likelihood

wrong-tag frac.f= ±1 for CP=1

PDGb-flavor tag

resolution functionB-lifetime studies


20

Results • Measurements on the unitarity triangle

– sin(2from b ccs

– sin(2eff from b sss

– and • Rare B decays: PP and VV• New particle states• Size of the triangle (Kim’s talk), theoretical interpr

etations (Li and Cheng), new physics (He)


21

sin(21) Measurement from bccs

2911 f = 1 events included in the fit.

J/ KL: 2332 with a purity of 60%;

f = +1

140 fb


22

MeasurementMeasurement of of sin2sin211 (Belle 2003) (Belle 2003)

sin21= 0.733±0.057±0.028

140 fb-1

Poor ta

gsGo

od

tag

s

|ccs| =1.007±0.041(stat)

i.e., consistent with no direct CPV.


23

Compare CP odd and CP even (Belle 2003)

CP = 1 sample

sin21

= 0.73±0.06

CP = 1 sample

(B0J/KL)

sin21

= 0.80±0.13


24

Measurement of 1() from BaBar

ΔE [MeV]

J/ψ KL signal

J/ψ X backgroundNon-J/ψ background

CP sample NTAGpurity ηCP

J/ψ KS (KS→π+π-) 2751 96% -1

J/ψ KS (KS→π0π0) 653 88% -1

ψ(2S) KS (KS→π+π-) 485 87% -1

χc1 KS (KS→π+π-) 194 85% -1

ηc KS (KS→π+π-) 287 74% -1

Total for ηCP=-1 4370 92% -1

J/ψ K*0(K*0→ KSπ0) 572 77% +0.51

J/ψ KL2788 56% +1

Total 7730 78%


25

BaBar Results with 205 fb (cc) KS (CP odd) modes J/ψ KL (CP even) mode

sin2β = 0.722 0.040 (stat) 0.023 (sys)


26

Belle Update with 253 fb

S = 0.722 0.040 ± 0.023

A = 0.950 0.031 0.013

250 fb-1


27

Dream of New Physics with CPV in Rare Decays

• In the SM for the pure bs transition,

• sin(2 1)eff (bsss) = sin(2 1)(bccs)

• Any deviation may mean new physics.

• Decay Modes: B KS ;

B KS ;

B KKKS;KsKsKs

B f0 KS, KS

• NTU is involved in this search.


28

Hunting for new phases in bs penguins

dominant

• Large exclusive and inclusive BRs.• New physics comes from the penguin loop.


29

CPV in the B KS decay

KS

Nsig=139 14

purity 0.63

pB*

KL

purity 0.17

Nsig= 36 15

274M BB

KS + KL

: S (K0) = +0.06 0.33 0.09

A (K0) = +0.08 0.22 0.09 ~2.2 away from SM

KS + KL

: S (K0) = +0.06 0.33 0.09

A (K0) = +0.08 0.22 0.09 ~2.2 away from SM

Belle


30

BaBar Result on B KS


31

Belle

B0’KS KKKSB0’KS KKKS

KKKS

Nsig=512 27purity 0.61


CP=+1: 1.03 0.15 0.05

Raw

Asy

mm

etry

Good tags Good tags

S = 0.736fit

0.170.0

Raw

Asy

mm

etry

(~0.5@SM) (~1.0@SM)

high statistics modes(excluded)

’

( , )

’KS

S = +0.65 0.18 0.04 S = +0.49 0.18 0.04 ( ) A = 0.19 0.11 0.05 A = 0.08 0.12 0.07

0.170.00


32

BaBar Results on KKKs


33

BaBar Results on KS/ f0 Ks


34

B0KS f0(980)KSadditional modes

Nsig=31 7

purity 0.56


S = +0.75 0.64 S = 0.47 0.41 0.08 A = 0.26 0.48 0.15 A = 0.39 0.27 0.08

Good tags

S = 0.736fit

0.130.16

Good tagsRaw

Asy

mm

etry

(~2.9@SM)(~0@SM)

274M BB

Belle


35

Another penguin mode B s Nsig=168 18

purity 0.55

Good tags

S = 0.736fit

Raw

Asy

mm

etry


36

TCPV in B0 KsKsKs from Belle

Poor tags

Good tags

(~2.8@SM)

“sin21” = 1.26 0.68 0.18 A = 0.54 0.34 0.08

w/ VTX w/o VTX total Nsig

3 ( 96 32 128 72

2 ((

21 18 39 16

total 117 50 167 88


37

Summary of 1() Measurements

sin21(bsqq) = 0.39 0.11 (Belle) 0.42 0.10 (BABAR)

CL = 1.2 104 (3.8)

World Average (WA)

sin21(bsqq)= 0.41 0.07 sin21(bccs) = 0.726 0.037


38

orxtraction

0

sin(2 )hh

hh

C

S

2eff

sin( )

1 sin(2 )

hh

hh hh

P T

C

S C

measure eff

need to bound |eff-| (shift from loops) different |Penguin/Tree| for different decays

:tdV

* :tdV

:ubV

+Loops (penguins)


39

Results

0.30 0.17 0.03

0.09 0.15 0.04

S

C

227×106 B pairs

467 signal events

LR

preliminary

0B

0B

S= 1.00 0.21 0.07-A= -0.58 0.15 0.07 = C

0B0B

152×106 B pairs372 signal events


40

Continue

• Belle has observed CPV in B at a level of 5.2

• 3.2 evidence for direct CPV from Belle

• Not supported by BaBar measurement

>3 difference betweenBABAR and Belle results

Average with care!


41

Observation of

0 0

0 0

6(117 0.32 0 10) 100 12 0.56 0.06

BF . .C .

o| - | 35 at 90% CLeff

(227e6 B Pairs)

4.9

6.0

First measurements of C00

(274e6 B Pairs)

B = (2.32 ) x 10-6 Signal: 82 16 (6.0)

0.440.48

0.220.18

ACP = 0.43 0.51 0.170.16


42

B


43

Isospin Correction for 2/


44

B +- is not a CP eigenstate• Cut on Dalitz plot to analyse bands• Analyse Dalitz plot

S

S


45

Quasi two-body Approach 0

| |/(1 ) ( )sin ( )costCPB

f t e S m t C m tCSA

related to

Low Quality Tag

High Quality Tag

BAsym : :Asym B

Belle

02.004.0

02.006.0

10.008.0

18.038.0

09.024.030.0

17.025.0

23.028.0

02.010.016.0

C

S

C

S

ACP

exp model102 11 15 Gronau & Zupan hep-ph/0407002


46

Time dependent Dalitz Analysis

CP Violating Observables:

Non-CP Observables:

0.088 0.049 0.013

0.34 0.11 0.05

0.10 0.14 0.04

CPA

S

C

03.011.015.0

03.015.022.0

C

S

Constraint on strong phase differenceBetween and 00 BB

)767( 2831

Convert measured parameters

into CPV observables


47

From time-dependent Dalitz Analysis

BBAABBARARBBAABBARAR

[degrees]

o27(113 6)17

BABAR CONF-04/038

[Theoretically Clean: SU(2)]

All strong phasesAnd amplitudes extracted from DP


48

Summary on 2/ Measurement

o

From combined

, , results:

9103 10

o

indirect constraint fi t: 98 16

CKM


49

3 () Extraction


50

Gronau London Wyler method

B- D0CPK(*)-, where D0

CP is a CP-eigenstate decay

(CP+: D0 π+π-, K+K- CP-: D0 Ksπ0)

We have the following observables:

4 observables (RCP+, RCP-,ACP+, ACP-) determine 3 unknowns (rB,δB,)

0 02

0

( ) ( )1 2 cos cos

2 ( )CP CP

CP B B B

B D K B D KR r r

B D K

0 0

0 0

( ) ( )2 sin sin

( ) ( )CP CP

CP B B CPCP CP

B D K B D KA r R

B D K B D K


51

GLW Results – BaBar

CP

CP

- 0.80 0.14 0.08

0.21 0.17

0.87 0.14 0.06

0.40 0.15 08

0

0

.

.

07C

C

P

P

R

R

A

A

0.040.1CP- 4

CP

0.33 ( 1.15 0.0.34 0.1 )0 12 ( )

0.76 0.29 0.0

1.77 0.37 0.12

0.09 0.20 0.0

6

6

CP CP CP

CP

A AA

R

A

R

Additional systematic erroron ACP- ( CP even background)

More CP eigenstate final states still to be added… More statistics needed to constrain More statistics needed to constrain

Loose bound on rB22(1 )CP CP BR R r

From DCPK*2 0.23 0.24Br

0.100.081.09 0.26

0.02 0.24 0.05CP

CP

R

A

D*0 (D0CP0)K -D*0 (D0

CP0)K -

NBB=214 106 NBB=227 106

NBB=123 106


52

GLW Results – Belle

B+ D*02 K+ statistical

significance 4.5 σ

B+ D1*0K+ statistical

significance 5.6 σ

Acp=-0.27±0.25 ±0.04

Acp=0.26±0.26±0.03

06.028.043.1

*

*

*1

*1

1

DB

KDBDB

KDB

R

06.028.094.0

*

*

*2

*2

2

DB

KDBDB

KDB

R

Acp=0.07±0.14±0.06

Acp=-0.11±0.14 ±0.05

08.016.029.1

0

0

02

02

2

DB

KDB

DBKDB

R

10.018.098.0

0

0

01

01

1

DB

KDBDB

KDB

R

250 fb-1


53

The Atwood-Dunietz-Soni MethodThe Atwood-Dunietz-Soni Method

0

0

| ( ) |0.060 0.003

| ( ) |D

A D K

A Dr

K

Input:

Count B candidates with opposite sign kaons Count B candidates with opposite sign kaons

([ ] ) ([ ] )2 sin( )sin /

([ ] ) ([ ] )ADS B D D B ADS

Br K K Br K KA r r R

Br K K Br K K

D decay into flavor stateD decay into flavor state

Phys.Rev.Lett.91:171801,2003

B D

D decay strong phase D unknown


54

ADS Results – BaBar

RADS

0.030 (90%CL)ADSR

0.23 (90% )Br CL

1

48 73

D

D

o o

any

r

any

D0K

3106

00 101π x)DD(R **

ADS319

130 1011γ

x)DD(R **ADS

D0K D*0(D00)K D*0(D0)K

NBB=227 106

1.30.8

2.

4.0.

1.4

2

1

3

*( )

*( )

([

([ ] )

] ) 0.2

([

.

)

7

] 1.2

4D

D D

D D

N K K

N

N

K

K

K

K

D

D*(Dπ)

D*(D)


55

ADS Results – Belle

However, not easy to directly determine

However, not easy to directly determine

R ADS can be translated to rB < 0.28 (90% CL)

RADS

30.7 ± 8.8 10178 ± 104

17.8 ± 7.1 535.0 ± 25.9


56

The The DD(*)0(*)0((DD00Ks Ks ))KK++ Dalitz Method Dalitz Method

3*1 ~~ AVVM uscb

3φ32 η i

cs*

ub e~)i(ρ~AλV~VM γ32 ηρλ i

cs*

ub e~)i(A~VV~M

Use 3-body final state, identical for D0 and

D0: Ksπ+π-.

Dalitz plot density:

22222 ||),(

sKsKsKsK

dmdmMmmd

22222222 |),(),(||),(|

ssssss KK

i

KKKKmmfremmfmmM

(r, , δ) can be obtained with simultaneous fit of B+ and B- data.

pioneered by Belle


57

Modeling D0Ks


58

Dalitz Analysis Results from BaBar

0.18 (90% )Br CL

D0K-

68% 95%

D0K-0

0.3

(130 45 8 10)oB

rB

-1800.30.

As for the D* modes: There is a phase shift between D* D0π and D* D0 γ as noted in hep-ph/0409281.The error on decreases significantly when this is accounted for!

As for the D* modes: There is a phase shift between D* D0π and D* D0 γ as noted in hep-ph/0409281.The error on decreases significantly when this is accounted for!

D0 modes alone = (73±45±10±10)º


59

Dalitz Analysis Results from Belle253 fb-1


60


61

Observation of Direct CP Violation

_B0 K B0 K

.

3.6


62

B VV : Polarization Puzzle

Penguin Anomaly ? New physics effect ?K*(bsss) only ?-

Naïve Factorization : Longitudinal fL = 1 – O(1/mb2)

fL(K*) ~ 0.5

QCD penguin annihilation: O(1/mb2) O(1)

f/ f = 1 + O(1/mb) ? fL(K) < fL(K*) ?

[K: pure b s Penguin]

B+u

u

b

uss

W

g

*+

VtsVt

b ts

KfL 1Tree dominated

Penguin only

(BaBar/Belle)

s

ud

d

*0


63

KPolarizationKPolarization

2D(,K* helicity) ML-fit (Mbc, E, mass signal region)

fL =0.50 0.19 0.050.07 (3.1 away from fL= 1 )

B = (6.6 2.2 0.8 ) x 10-6

bkg (fixed)

K(fixed)

Transverse

helicity K helicity152M BB-


64

KPolarizationKPolarization　 89M BB-

Nsig = 141 2324 (>5

fL =0.79 0.08 0.04 0.02 B = (17.0 2.9 2.9 ) x 10-6

0.01.9

ACP = 0.14 0.17 0.04

[BaBar-conf-04/34]

ML fit to all distributionssimultaneously

BaBar + Belle likely fL < 1

BaBar + Belle likely fL < 1

non-resonantcontribution

1st observation


65

B K* : New Physics SearchB K* : New Physics SearchTransversity basis:Angular distribution PK*( tr, tr, K* ; A0, A//, A)

A0 : longitudinal (CP= +1)A// : transverse CP= +1A : transverse CP= 1

2 sets _(B, B)

= f= (|A|2+ |A|2)/2, = (|A|2|A|2)/2

i = Im(AAi*+AAi

*), i = Im(AAi*AAi

*)//0 = Re(AA0

*+AA0*), //0 = Re(AA0

*AA0*)

Direct CPV

Triple-prod. (T-violation)

( |A|2+ |A|2 + |A|2 =1 ) “0” NP[e.g. London, Sinha2, PRD69,114013(04)]

(i = 0, //)

(12-1 parameters)


66

97 signals

1211

46 signals

98

fL =0.51 0.06 0.04

confirm low fL

K*0

K*+

B K*


67

B K* : New Physics Search

“0” NP

Triple product (T-conserving)

Triple product (T-violating)

f/ f ~ 1

FSI

152M BB-


68

B K* : New Physics Summayarg(A/A) 2.34 0.23 0.05(-2.34) -2.21 0.22 0.05

arg(A/A) 2.47 0.25 0.05(0.67) 0.64 0.21 0.06

Belle (152M)BaBar (227M)

No indicationof NPexcept fL puzzle

“0” NP

BaBar/Belle consistent


69

’J/

X(3872) 10σ

Belle

MeV

MeVM

3.2

5.06.00.3872

at 90% C.L.

•No evidence of X X J/ 0.

6)/(/)(

7)/(/)(

6.0)/(/)/(

40.0)/(/)/(

1.1)/(/)(

89.0)/(/)(

000

2

1

JXDDX

JXDDX

JXJX

JXJX

JXX

JXX

c

c

•First Observed by Belle.

•Confirmed by CDF, D0 and BaBar

•Searh for other decay modes

M(J/) –M(J/)

X(3872)


70

Another X(3872) decay mode

M(J

/

)

BK X(3872)

• Belle observed a new decay mode of X(3872) *J/ +-0J/

(XJ/)/(X J/) = 0.8 ±0.3± 0.1

Nevt=10.0 ± 3.6Signif = 5.8


71

DsJ(2317) and DsJ(2460)

CLEO Belle

DSJ(2317)

DSJ(2460)

DSJ(2317)

DSJ(2460)

DSJ(2460)

)( 0SDM

)( 0SDM

)( 0*SDM

0SD

0*SD

SD

KKDS

0 KKDS

)( sJDM

BaBar - DsJ(2317)


72

Threshold Peaking

ppK


73

Threshold Enhacement• If it is fit with a BW:

• Significance: > 8

Belle

BKJ/MeV

MeVM

2492

113941


74

Summary• B factory experiments are very productive: – Establish mixing induced CP violation in two years – Observe direct CP violation – andextractions become feasible. – new states, B decay properties and fine measmnt.• Future focus: – Standard Model parameters; – Probe new physics, i.e. CPV on bsss, BVV – Refine measurements and search for new decays• Fierce but healthy competition between Belle and BaBar


75

CPV in B

N(total)= 163±18

A 0.77 0.27 0.08

S 1.23 0.41 0.070.08

Rule out the CP-cons. case (A,S = 0,0)at CL = 99.93%


76

CPV in B

BaBar 113fb-1 Results BaBar 113fb-1 Results N= 266±24

A C 0.19 0.19 0.05

S 0.40 0.22 0.03

B0 tagged

B0 tagged

AK 0.107 0.041 0.013( )

Documents

Experimental Overview of B Physics