6/4/2004 1

Particle Physics 2004Birmingham5th-7th April

Adrian Bevan

Physics at the B-factories

6/4/2004 2

• Current generation of B-factories

• CP Violation Studies: , ,

• Rare Decays

• New Particle Searches

• Physics

• Conclusions

Talk Outline

6/4/2004 3

The B-factories• PEP-II and KEK-B at SLAC and KEK, respectively• Collide e+ and e- with a 10.58 GeV CM energy• Detectors: BaBar and Belle• Started data taking in 1999

•9GeV e- on 3.1GeV e+ (4S) boost: =0.56

6/4/2004 4

)MeV(ME )S4(CM (4S) decays into B+B- or B0B0

•Cross Sections at (4S): 1.1

1.3

, 0.3

1.4

bb nb

cc nb

dd ss nb

uu nb

“continuum background”

thresholdBB

(4S)

off-peak

0 0

( (4 ) )1.04 0.07 ( 2003)

( (4 ) )

BF S B BPDG

BF S B B

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BaBar

SVT

DCH

DIRC

EMCIFR

SOLENOID

e+

e-

Belle

The Detectors

Differences between BaBarand Belle are small

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Peak Lumi: 8.16×1033 cm-2 sec-1

Number of B pairs approx: 200×106

run

1

run

2

run

3

run

4

Peak Lumi: 12×1033 cm-2 sec-1

Number of B pairs approx: 220×106

Data Samples

6/4/2004 7

Why is CP Violation so important?• Matter/anti-matter asymmetry in the universe requires CP Violation

known level of CPV is 109 times too small for cosmology

• Standard Model describes all CPV with a single complex phase

need to test

• Flavour physics BSM has many parameterscan search indirectly for new physics and try to

(further) constrain models before the LHC

CP Violation Studies:

6/4/2004 8

The couplings, Vij, form a 3×3 matrix: The CKM Matrix;

CP Violation in meson decay

32

2 2

23

4

(1 / 2 )

(1 1)

1 / 2 ( )

A i

i

V A

AA

O

Understanding Standard Model CP Violationmeans accurate measurements of and

V , ,iq u c t

, ,jq d s b

W

ijV

~ 0.22

~ 0.8

~ 0.2 0.27

~ 0.28 0.37

A

Wolfenstein Parameterisation:

6/4/2004 9

| |

| |

itd td

iub ub

V V e

V V e

mixing0 0B B

* * * 0ud cd cub tdb tbV V V VV V

(1,0)(0,0)

(,) *

*td tb

tcd cb

V VR

V V*

*ub ud

bcd cb

V VR

V V

* , ,

,...

B D DK

K

, ,B

0

* *

/ ,

, ,...

SB J K

D D K

The Unitarity Triangle

SM Predicts a closed triangle withtwo independent phase angles: &

6/4/2004 10

• Three observable interference effects:

– CP violation in mixing:

– (direct) CP violation in decay

– CP violation in interference of mixing and decay (Im ≠ 0)

0 0 0 0Pr( ) Pr( )B B B B time dependent effect

time dependent effect – relevant formeasuring CKM angles!

CP violation at the (4S)

0 0Pr( ) Pr( )B f B f time integrated effect – number counting

0B

0B

f

6/4/2004 11

00

0 0

( ( ) ) ( ( ) )( )

( ( ) ) ( ( ) )

sin( ) cos( )

physphysCP

phys phys

B t f B t fA t

B t

S m t C m

B f

t

f t

Analyse time evolution of BB system (assume ):

Indirect CP violation S ≠ 0

Direct CP violation C ≠ 0

00

4

( / / , )

1 sin( ) cos( )

phys

td d

f B B f f t

e n m t nCS m t

0 01( 1) for ( )n B B

6/4/2004 12

(1,0)(0,0)

(,)

* , ...B D DK

,B

0

0 0 0

/ ,

, ...

S

S

B J K

K f K

Measurements Related to the angles of the Unitarity Triangle

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The CKM Angle :

Precision measurement of from bccs Perfect agreement with the SM Prediction

Alternate measurements of probe NP at TeV

scale

sin 2 0.736 0.049 (Belle & BaBar)

6/4/2004 14

B0 K0The CKM Angle :

• Rare Decay

• loop or “pure penguin”

• sensitive to new physics

• measured in this mode should agree with

• So in SM:

0( / )Sb ccs J K

sin 2 , 0s sK KS C

[sin 2 ( ) 0.736 0.049]b ccs

6/4/2004 15

( )b sss

106 candidates

(from 152×106 B pairs)PRL. 91 (2003) 261602

B0 K0S

0.96 0.50 0.10

0.15 0.29 0.07

S

C

3.5 deviation for S in KS

Belle Claim “evidence for new physics”

SM=+0.74

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B0 → K0

120 M BB

BaBar Result consistent with SM

Preliminary

hep-ex/0403026, submitted to PRL

B0 → KL

B0 → KS

0.320.360.47 ( ) 0.06( )

0.01 0.33( ) 0.10( )K

K

S stat syst

C stat syst

6/4/2004 17

The CKM Angle :

ccs

new hep-ex

new result

new result

6/4/2004 18

The CKM Angle :

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CP Violation in B→hhh

0

sin(2 )

C

S

Tree Level: +Loops (penguins)

u,c,t

W

2eff

sin( )

1 sin(2 )

C

S C

measure eff

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

:tdV

* :tdV

:ubV

6/4/2004 20

0.40 0.22 0.03

0.19 0.19 0.05

0.107 0.041 0.013K

S

C

A

Presented at LP ‘03 results for S and C124×106 B pairs

0B

0B

266 signal events

-A= -0.58 0.15 0.07 = CS= 1.00 0.21 0.07

LR

0B0B

Observation of CPVEvidence for DCPV

152×106 B pairs372 signal events

preliminaryhep-ex/0401029

6/4/2004 21

Isospin Analysis: need B+-, +0 and 00 limiting factor is B→

• Small signal BR• qq and background

Significance including

systematic errors = 4.2

0 0

1413

0 0 0 6

46 3

( ) (2.1 0.6 0.3) 10

N

BR B

PRL 91 (2003) 241801

124×106 B pairs

0| | 48

(90% . .)

eff

C L

Can’t do Isospin analysis in without a super B factory

Stuck with model dep. interpretation in

6/4/2004 22

B

0

6

(30 4 5) 10

(BaBar)

0.99 0.03 0.04L

B

BF

f

run 1+2

0 0

6

0.050.07

(26.4 6.4) 10

(Belle & B

0.96

aBar)

L

B

BF

f

0 0 0

6

(Ba

2.1 10 (90% . .

r)

)

BaB

BF C L

| | 13 (68% )eff CL Penguins are small in B

No observation published prior to last year now have measurements of all modes

6/4/2004 23

Preliminary Result

96 10 4 13stat syst theory

Isospin analysis gives:

0.19 0.33 0.11

0.23 0.24 0.14

long stat syst

long stat syst

S

C

run 1+2+3B

0B

0B

• ~113/fb• 314 signal events

6/4/2004 24

The CKM Angle :

2 of many methods under study: Full & Partial reconstruction of BD(*): sin(2+)

5207 ± 87 signal

4746 ± 78 signal

Full Reconstruction

82/fb

using 78/fbOnly consider D* with l or K in other B

O(50%) purityuse hard pion from B decay and soft pion from D* decay.No low efficiency from D0 reconstruction

hep-ex/0308048 & hep-ex/0310037 (BaBar)hep-ex/0308048 (Belle)

Partial Reconstruction

High Purity Lower Statistics

lepton kaon

6400 signal 25160 signal

Preliminary

6/4/2004 25

sin(2+) > 0.87 (68% CL)

sin(2+) > 0.58 (95% CL)

Combining results of both BaBar methods

Preliminary

6/4/2004 26

Direct CP Violation• Interference of diagrams with different strong and weak phases• ’ in kaon system only observed manifestation

Only hint from Belle’s +-

Need More Data

( ) ( )

( ) ( )CP

Br B f Br B fA

Br B f Br B f

6/4/2004 27

Measurements Related toSides of the Unitarity Triangle

(1,0)(0,0)

(,) *

*tb

tc

td

cd bV

VVR

V*

*ud

bc

ub

cd bV

VVR

V

b s

semi-leptonic B decays

6/4/2004 28

Use model from Gambino and UraltsevMeasurement of Vcb from semileptonic B decays

8 parameter fit includes: |Vcb|, BR(XCe), mb and mc

GeVGeVm

GeVGeVm

eXBBr

V

c

b

c

cb s

)02.006.007.018.1()1(

)02.004.005.061.4()1(

)%06.016.061.10()(

10)6.02.04.04.04.41(||

s

s

SL

HQEexp

HQEexp

HQEexp

3HQEexp

B(B→Xclν), |Vcb| and mb determined with

precision of 2% or better!

hep-ex/0403031, hep-ex/0403030Thanks to Henning Flaecher Preliminary

6/4/2004 29

B → K*• Acp ≤1% in SM.

• SUSY can enhance to ~20%

Reconstruct ~1150 signal in: ss KKKKK ,,, 00

88×106 B pairs

*K K CPA

preliminary

e.g. MSSM constrainthep-ph/0303043

(Ellis et al)

*B K WMAP

excluded by th.

Preliminary

6/4/2004 30

Non CP/UT physics from BaBar

Too much physics activity to do justice to all areas: We have work published/under study in many areas including:

• New Particle Searches• Rare B decays• Direct CP Violation Searches • physics

lots more areas under study that I don’t have time to discuss.

6/4/2004 31

New Particle Searches• Last Spring from BaBar:

discovery of cs state: DsJ(2317)evidence for Ds(2458)

• Ongoing work searching for Pentaquarks

revitalised charm meson spectroscopyBelle and CLEO confirmed this discovery

led to improvement in theoretical models State was found below DK threshold (previously assumed to be above threshold)

Now have many BDsJX branching fractions

See: 2317: Phys.Rev.Lett. 90 (2003) 242001  105 citations! 2458: Phys.Rev. D69 (2004) 031101

0SD K K

SD K K

data favour JP=0+

6/4/2004 32

Belle Observe BXSll, XS=K, KSfrom Iwasaki’s talk at

http://moriond.in2p3.fr/EW/2004/

• 72 Signal Events• 6.2 significance• 140/fb, 152×106 B pairs

*B K llAlso study where BF~7×10-7

• Rare Decay (FCNC)• Sensitive to NP

(results available from both expts)

6/4/2004 33

Physics: Overview

= 290.8 ± 1.5stat ± 1.6syst fs lifetime: 30/fb

LFV decay searches: 91.5/fb

6( ) 2.0 10 (90% C.L.)BF

Rare decays

6(56 10 pairs)

signalbox

Preliminary

6/4/2004 34

• BaBar has first measurement of from B

• Belle Observes CPV in B & sees hint of Direct CPV

• Starting to test closure of the Unitarity triangle

• Everything measured so far consistent with SM

• Searching for New Physics at higher order: looking closely at bs penguins: new measurements of

• Will have ~200-250/fb per experiment for ICHEP ’04 (approx ×2-3 increase in stats over results shown)

Conclusions

6/4/2004 35

sin(2 )

cos(2 )

sin(2 )

Knowledge of , from direct measurementssin(2 )

B b ccs

(*)B D

/ *B J K

Constraints from:

CPV from B system is consistent with SM

6/4/2004 36

Additional Material:

6/4/2004 37

B0 → f0 K0 (CP even decay)0B

0B

6/4/2004 38

/ * (cos 2 )B J K

/ * is a VV decay - has both CP even and CP odd partsB J K• cos(2) comes from interference between helicity states

104 tagged events (KS0)

0.760.96cos 2 3.32 ( ) 0.27( )

sin 2 0.10 0.57

stat syst

0.500.79

With WA sin 2

cos 2 2.72 0.27

6/4/2004 39

b lsl• Rare Decay (FCNC)• Sensitive to NP

SM BF~7(1)×10-6 (ee) ~4(1)×10-6 ()

Ali: PRD 66 034002 (2002)Ali: hep-ph/0210183

peaking BG component from charmonium and hadronic B decays

0 or SK K

or e e

c.f. 0.02(0.20) in SMESM

Preliminary

6/4/2004 40

Isospin Analysis

)Br()Br(2

)Br()Br()Br(cos

0

00210

| |eff

0 0 0

2

0

Bsin ( )

Beff

Br

Br

Grossman Quinn bound

Also see Charles, GLSS, Buchalla et al…

6/4/2004 41

0| |/(1 ) ( )sin ( )cosX

CPt

XB X XXXf t e SA Cm t C m tS

related to

direct CPV

K is self tagging

CK, SK, SK =0, CK =-1 •large expected:

ACP() & ACP(K)

6

1.3 61.2

( ) (22.6 1.8 2.2) 10

( ) (7.3 1.3) 10

B B

B B K

0 / : Not A CP EigenstateB K

BF From Winter ’03 (82/fb)

804.2 ±49.2signal events

doing analysis in region near Dalitz Plot analysis goal

6/4/2004 42

cos( ) sin( )C m t S m t

~123106 B pairsLP ‘03 result (113 /fb)

2.4

A

A Difficult to relate to without DP analysis

6/4/2004 43

*B K ll

6/4/2004 44

0

0

6/4/2004 45

6/4/2004 46

The whole picture for B-meson decay:

CP Violation in mixing: • so this is small

Direct CP Violation:• So far only seen in kaon decays• this can be a large effect in rare B decay

- Belle claim ‘evidence for’ in decay

Indirect CP Violation – CPV in interference• Need to measure the unitarity triangle angles

, ,

0 0

0 0

Pr( )1

Pr( )

B B

B B