experiment - university of houston

1

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ExperimentalHighEnergy

Physics(HEP)

YongshengGao

SouthernMethodistUniv.

June12,2002atQuarkNetatSMU

WhyisHEPinteresting?

WhatquestionsHEPaddresses?

CurrentfocusofExperimentalHEP

CESR/CLEOandselectedresults

FutureOutlook

TalkatQuarkNetonJune12,2002

YongshengGao,SouthernMethodistUniv.

2

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ASimpli�edPictureofHighEnergyPhysics

Inourendeavortounderstandrealitywearesomewhatlike

amantryingtounderstandthemechanismofaclosedwatch.

Heseesthefaceandthemovinghands,evenhearsitsticking,

buthehasnowayofopeningthecase.

Ifheisingenius,hemayformsomepictureofamechanism

whichcouldberesponsibleforallthethingsheobserves,

buthemayneverbequitesurehispictureis

theonlyonewhichcouldexplainhisobservations.

|AlbertEinsteinin1938



3'&

$%

Building blocks of matter

Anaximenes (� 500 BC):

Air

Water Fire Earth

Mendeleev (� 1869): The Periodic Table

Our current picture: The Standard Model

0BBBB@u

d1

CCCCA ;0

BBBB@c

s1

CCCCA ;0

BBBB@t

b1

CCCCA ;0

BBBB@�e

e1

CCCCA ;0

BBBB@��

�1

CCCCA ;0

BBBB@��

�1

CCCCA ;

g, , W�, Z

Talk at QuarkNet on June 12, 2002 Yongsheng Gao , Southern Methodist Univ.

4'&

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Success of the Standard Model

� High Energy (Tevatron, LHC)

� High Luminosity (CESR, PEP-II, KEK-B)

CORNELLSTANFORD

FERMILAB CERN

DESY NOVOSIBIRSK

KEKBEIJING

II

e+ep p

I

e+e

I

e+e

I

e p

I

e+e

I

e+e Ie+e

2230498-002


5

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$%

WhySM

isnotthefullstory?

�

\Replication"problem

�

Freeparameters

�

Matter-antimatterasymmetry

PhysicsbeyondtheStandardModel:

�

Newparticlessearch

(LEP,Tevatron,LHC)

�

Neutrinophysics

(Super-K,Minosetc)

�

CPviolationstudy

(B-factoriesetc)



6

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WhatisCP

Violation?

�

C:Chargeconjugation

�

P:Parityre ection

CPViolation!di�erencebetween:

�

Matterinuniverse

�

Antimatter,mirroruniverse

�

Matter-AntimatterasymmetryintheUniverse

ObservationofCPviolation:

�

ObservationofCPviolationinKaonsystem(1964)

�

ObservedCPviolationinBmesonsystem(2001)



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Test the SM and Search for New Physics

0BBBBBBBBB@Vud Vus Vub

Vcd Vcs Vcb

Vtd Vts Vtb1

CCCCCCCCCA'

0BBBBBBBBB@

1� �22

� A�3(�� i�)

�� 1� �22

A�2

A�3(1� �� i�) �A�2 1

1CCCCCCCCCA

α

γ β

VudVub

VcdVcb

Vtd V

tb

*

*

*b c l

Kν

B J/ΨKB π πB πB D Kcp

o

BB π π

b u l ν

s

Bo

_B

omixing

B ρ γ

π, K ππ

πρ

B Φ


8'&

$%

Cornell Electron Storage Ring

CESR: e+e� atp

s ' 10 GeV.

� On �(4s) resonance:

Æ e+e� ! �(4s)! B �B, e+e� ! Continuum

Æ B( �B) momentum ' 350 MeV/c (at rest!)

� Continuum: e+e� ! e+e�; �+��; �+��; u�u; d �d; s�s; c�c

9.44 9.46

Mass (GeV/c2)

0

5

10

15

20

25

σ (e+ e- →

Hadro

ns)(nb

) ϒ(1S)

10.00 10.020

5

10

15

20

25

ϒ(2S)

10.34 10.370

5

10

15

20

25

ϒ(3S)

10.54 10.58 10.620

5

10

15

20

25

ϒ(4S)


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CLEO Collaboration

�� 22 institutions and � 150 physicists

CORNELL

2231298-006CAL TECHUC-SAN DIEGO

UC-SANTA BARBARACARLETON

COLORADO

FLORIDA HARVARD

HAWAI

I

ILLINOIS

ITHACA COLLEGE

KANSASMCGILL

MINNESOTAOHIO STATE

OKLAHOMA

PURDUEROCHESTER

SLAC

SOUTHERN-METHODIST

SUNY

-ALB

ANY

SYRACUSE VANDERBILT

VIRGINIA TECHWAYNE STATE


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CLEO Detector

� �

Helium Reservoir

Muon Chambers

Magnet Yoke

Superconducting CoilBarrel Shower DetectorDrift Chamber

Micro-Beta QuadrupoleVertex DetectorEnd Cap Time of FlightPole Tip Shower DetectorTime of Flight Scintillators

SVX Detector

0 1 2 3 4

Meters

raf

CLEO II

� Oct.'89 { Apr.'95

� N(BB )= 3:3� 106

� 6-layer straw tube

CLEO II.V

� Nov.'95 { Feb.'99

� N(BB )= 6:4� 106

� 3-layer Si vertex detector

CLEO III

� 2000 { 2001

� New SVX, DR and RICH


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Experimental challenges in HEP/CLEO

� How to identify � 30 signal events from:

Æ 40,000,000 continuum events

Æ 10,000,000 generic B events

Æ Other signal-like events (Physics Backgrounds)

3600398-004


12

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PowerofHSPinHEP

�

MB

=r

E2bea

m

�

p2can

d

(�M

�

2:5�

3:4MeV=c2)

�

�E=Ecand�

Ebeam

(��

20�

60MeV)



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Selected CLEO Results: Rare B Decays

u

d, su

u, d

Wb

u, d

( a )

B+, B0 B+, B0

b

u, d

t, c, u

Wd, sq

qu, d

g

( b )

b

u, d

uu

d, s

W

u, d

( c )

I

I II I

II

I I

I

I

I

I

I

I

W

( d )

t, c, u

I I I

Z,

q

q

I

u, d

d, s

II

b

I

u, d B+, B0

3460997-007

B+, B0

� Unitarity triangle (angles � and , CKM elements Vub, ......)

� Sensitive to physics beyond the Standard Model


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B ! ��, K� and KK Results

N

NK

12

3

4

5( a )

( e )

( d )

( b )

( f )

+30

0

4 8

0

20

16012080400

20

40

60

80 1.00

0.2005.305.255.20

0.90

0.95

0.50 1.00

0

2861199-013

R sig

R

Even

ts / B

in

M (GeV) E (GeV)

+IK+I

( c )+IK

+I

+ I + I

0.20I0

0

24

16

8 10


15

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B!

��,K�andKK

Results

Mode

Nsig

Sig.

EÆciency

BR�

106

�+��

20:0+7:6

�6:5

4:2�

48%

4:3+1:6

�1:4�

0:5

��0

21:3+9:7

�8:5

3:2�

39%

<12:7(90%C:L:)

�0�0

6:2+4:8

�3:7

2:0�

29%

<5:7(90%C:L:)

K��

80:2+11:8

�11:0

11:7�

48%

17:2+2:5

�2:4�

1:2

K��0

42:1+10:9

�9:9

6:1�

38%

11:6+3:0

�2:7+1:4

�1:3

K0��

25:2+6:4

�5:6

7:6�

14%

18:2+4:6

�4:0�

1:6

K0�0

16:1+5:9

�5:0

4:9�

11%

14:6+5:9

�5:1+2:4

�3:3

K+K�

0:7+3:4

�0:7

0:0�

48%

<1:9(90%C:L:)

K�K0

1:4+2:4

�1:3

1:1�

14%

<5:1(90%C:L:)

K0�K0

0

0:0�

5%

<17(90%C:L:)

�

PublishedinPhys.Rev.Lett.85,515(2000)

�

hep-ex/0103040,CLNS01/1718,submittedtoPRL



16

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B!

PVandVVResults

DecayMode

BR�

106

TheoreticalPrediction�

106

��0

10:4+3:3

�3:4�

2:1

0.4�

13.0

��

27:6+8:4

�7:4�

4:2

12�

93

�0�0

<5.5

0.0�

2.5

K��0

<17

0.0�

6.1

��K�0

<16

3.4�

13.0

K�K�0

<5.3

0.2�

1.0

�0�0

<4.6(5.9)

0.54�

2.5

K�0�0

<13(19)

0.7�

6.2

K�0

�K�0

<8.7(10)

0.28�

0.96

�


�

hep-ex/0101029,CLNS00/1705,submittedtoPRL



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Observation of B ! �K(�)

B

b

W

t

g

s

s

sK(*)

d,u

I I

I

d,u

I I

6

4

2

0

5

05.20 5.25 5.30 0.2 0.20I

mB (GeV) E (GeV)

( a )

( c )

1631200-007

( b )

( d )

8

4

0

8

4

0

12

Num

ber o

f Eve

nts

/ Bin

� Clean signature for gluonic penguin

� Sensitive to Vts


18

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ObservationofB!

�K(�)

Mode

Nsig

Sig.EÆcienty

BR

�

106

�K�

14:2+5:5

�

4:5

5:4�

54%

5:5+2:1

�

1:8�

0:6

�K0

4:2+2:9

�

2:1

2:9�

48%

<

12:3(90%C:L:)

�KCombined

6:1�

5:5+1:8

�

1:5�

0:7

�K�0(K��+)

12:1+5:3

�

4:3

4:5�

38%

9:9+4:3

�

3:5�

1:6

�K�0(K0�0)

5:1+3:9

�

2:8

2:7�

20%

46:3+35:7+5:9

�

26:0�

6:6

�K�0Combined

5:1�

11:5+4:5+1:8

�

3:7�

1:7

�K��(K��0)

3:8+4:1

�

2:8

1:5�

25%

9:3+10:1+1:7

�

7:0�

1:5

�K��(K0��)

4:0+3:1

�

2:2

2:7�

32%

11:4+9:0

�

6:3�

1:8

�K��

Combined

3:1�

10:6+6:4+1:8

�

4:9�

1:6

�K�Combined

5:9�

11:2+3:6+1:8

�

3:1�

1:7

�

hep-ex/0101032,tobepublishedbyPRL



19

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b!

s

�

EW

penguin

V�ts V

tb

�

SM

prediction:

B(b

!

s )=

(3.28�

0.33)

�

10�4

�

Sensitive

to

New

PhysicsbeyondSM



20

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Experimentalchallengeinmeasuringb!

s

��

��

��

��

��

��

��

��



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AnalysisStrategyinmeasuringb!

s

�

Selectphotoncandidate:

2.0GeV<E

<2.7GeV

�

SuppressionofContinuum

background:

Æ

\pseudoreconstruction"

Æ

\leptontag"

Æ

Eventshapevariables(neuralnet)

�

Subtractbackgroundsfrom

�0,�,andotherBdecays



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b ! s Results

On - Off Subtracted data

BB MC

Spectator Model

On - Off - BB Subtracted Data

Eγ (GeV)2 3 4 5

2 3 4 50

200W

eight

s per

0.1 G

eV

0

50

� B(b! s ) = (3.21 � 0.43 +0:32

�0:29) � 10�4

� SM prediction: B(b ! s ) = (3.28 � 0.33) � 10�4


23

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ExclusiveFCNCProcesses:B!

l +l�

K(�)

�

SuppressedinSM:

BR�

(10�6to10�7)

�

SensitivetoPhysicsbeyondSM:

SUSYetc

StrategyinSearchingforFCNCProcesses

�

SelectLeptoncandidates

�

SelectKaoncandidatefrom

pionbackgrounds

�

SuppressPhysicsBackgrounds:

Æ

B!

J= K(�)whereJ= !

e+e�

or�+��

Æ

B!

(2S)K(�)where (2S)!

e+e�

or�+��

�

SuppressContinuum

andotherBbackgrounds:

Æ

EventShapevariable,

MissingEnergy,etc



24

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CLEOExclusiveFCNCResults

DecayMode

EÆciency

EvtsObsved

BRUL(90%

CL)

B!

K0e+e�

4.8%

1

<8.5�10�6

B!

K0�+��

3.3%

0

<7.2�10�6

B!

K�e+e�

15.6%

1

<2.4�10�6

B!

K��+��

8.4%

1

<4.5�10�6

B!

Kl +l�

32.2%

3

<1.9�10�6

B!

K��(K0��)e+e�

2.0%

0

<11.9�10�6

B!

K��(K0��)�+��

1.2%

0

<20.1�10�6

B!

K��(K��0)e+e�

1.4%

3

<46.4�10�6

B!

K��(K��0)�+��

0.7%

0

<34.2�10�6

B!

K�0(K��)e+e�

8.0%

1

<4.8�10�6

B!

K�0(K��)�+��

3.9%

0

<6.2�10�6

B!

K�0(K0�0)e+e�

0.6%

0

<43.0�10�6

B!

K�0(K0�0)�+��

0.2%

0

<145.23�10�6

B!

K�l +l�

18.0%

4

<3.8�10�6



25

'&

$%

CPAsymmetriesinb!

s

�

Measuretheasymmetry:

ACP

�

�(b!s )��( �b!�s )

�(b!s )+�( �b!�s )

�

StandardModelPrediction:

ACP

<1.0%

�

NonStandardModelPrediction:

ACP

�

(10�

40)%

�

Analysisstrategy:

Æ

2.2GeV<E <2.7GeV

Æ

FlavorTagby\pseudoreconstruction"and\leptontag"

Æ

Mistakerates,On-o�subtraction,particledetectionbiases

�

ACP

=(�0.079�

0.108�

0.022)(1.0�

0.030)

�0.27<ACP

<+0.10

at90%C.L.



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CP Asymmetries in other B Decays

� Search for CP violation in self tagging decays

� Measure the asymmetry: ACP �

B( �B! �f)�B(B!f)

B( �B! �f)+B(B!f)

� Prediction: ACP � � 0.1% (Ali, Kramer, Lu, PRD 59,

014005 (1999))

K+ I

K+ 0

K +0

K+

+ 0

I1.0 1.00.50.00.5I

2861099-012

ACP


27

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CPAsymmetriesinotherBDecays

DecayMode

Nsig

ACP

Prediction

B!

K��

80+12

�

11

�0.04�

0.16

(+0.037,+0.106)

B!

K��0

42:1+10:9

�

9:9

�0.29�

0.23

(+0.026,+0.092)

B!

K0s ��

25:2+6:4

�

5:6

+0.18�

0.24

+0.015

B!

K��;

100+13

�

12

+0.03�

0.12

(+0.020,+0.061)

B!

!��

28:5+8:2

�

7:3

�0.34�

0.25

(�0.120,+0.024)

B!

J= K�

534

+0.018�

0.043

<

0.04

B!

(2S)K�

120

+0.020�

0.092

<

0.04

�


�




28

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SearchforCPViolationinD0Decay

PossibleCPviolationinCabibboSuppressedD0decays:

�

Atleasttwopaths(tree,exchange,penguin)

�

Same�nalstatewithdi�erentCP-odd,CP-evenphases

�

SensitivetoNewPhysics:

Æ

StandardModelExpection:

ACP

O(0:1%)

Æ

NewPhysicscanenterintheloops



29'&

$%

Experimental Technique

� Decay chain: D�+ ! D0�+s

� Use SLOW �+s to tag D0 avor at production

� Re�t slow pion: Q � M(D0cand�+

S ) � M(D0cand) � M�

��

��

Slow Pion

D decay vertexo

Silicon Detector

Beam Spot

Other charmedhadron

Primary Vertex

Reconstructed trackwithout refit


30'&

$%

Q resolution after re�t

D*+ → D0π+, D0 → K-π+

0

2000

CLEO II.VDATA

Events/

100 keV

13,527 ± 116 a)Events

σQ = 190 ± 2 keV

1

10

10 2

10 3

0 2.5 5 7.5 10

b)

Q (MeV)

Events/

100 keV

� Same technique we measured �(D?+) = 96� 4� 22 MeV


31

'&

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CPViolationinD0!

K+K�

,�+��

�

SelectD0!

K+K�(�+��)

�

Useslowpiontagfrom

D�+

!

D0�+S

�

FitQdistributiontoobtainyields

�

MeasureCPasymmetryACP(KK)

�

ACP(KK)=

�(D0!K+K�

)��(D0!K+K�

)

�(D0!K+K�

)+�(D0!K+K�

)



32'&

$%

CP Violation in D0 ! K+K�, �+��

Q Fits for KK CP Rates

D*+ χr2=0.85

D*- χr2=1.10

Q (MeV/c2)

0

500

-60

0

60

0

500

0 5 10 15 0 5 10 15 20

-60

0

60

Q Fits for ππ CP Rates

D*+ χr2=1.21

D*- χr2=1.16

Q (MeV/c2)

0

100

200

300

-60

0

60

0

100

200

0 5 10 15 0 5 10 15 20

-60

0

60

� 1512� 47 D0 ! K+K� events 579� 26 D0 ! �+�� events

� 1511� 47 D0 ! K+K� events 557� 26 D0 ! �+�� events


33'&

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CP Violation in D0 ! K+K�, �+��

Summary of ACP(KK)

0-10-20-30 10 20 30

ACP(KK) %

E691 (1991)

E687 (1994)

CLEO II (1995)

E791 (1998)

FOCUS (2000)

CLEO II.V (2001) prelim

CLEO II.V ACP (K+K�) = (0:1� 2:2� 0:8)%

Summary of ACP(ππ)

0-5-10-15 5

ACP(ππ) %

E791 (1998)

FOCUS (2000)

CLEO II.V (2001) prelim

CLEO II.V ACP (�+��) = (2:0� 3:2� 0:8)%


34

'&

$%

CLEOII+II.Vdata

(13.5fb�

1)

�

RareBdecays:B!

PP,PV,VV,�K(�),l +l�

K(�);b!

s

�

CPViolationinBandCharm

Decays

�

FirstObservationofB0!

D(�)0�0andB!

D��

�

FirstObservationofB!

D(�)K��

�

CPViolationinTauDecays

�

MeasurementofCKM

ElementsVubandVcb

CLEOIIIdata

(9.2fb�

1)

�

FirstpreliminaryphysicsresultsreportedatLP01



35'&

$%

The past/present/future of CESR/CLEO

2230398-001

A Brief History of CLEOCLEO Integrated Luminosities

CLEO III

CLEO II.5

CLEO II

CLEO I.5

CLEO I

CLEO Related

CESR Related

1980 1985 1990 1995 2000 2005 2010

109

108

107

106

105

104

BB

/ Ye

ar

b c

Mixingb u

b sK , K,

/

NewTracking

CsI

2cm BPSilicon

3.5cm BP

He-propane

Particle IDNew

Tracking

Microbeta7 Bunches

1 IR

Crossing Angle9X3 Bunches

SC IR QuadsSC RFI


36

'&

$%

TheCLEO-cProposal

�

ModifyCESR/CLEOforHighLumi.@3�

4GeV

�

CLEO-cWorkshop,Snowmass,ProposaltoNSF

�

ExpectedCESRperformance:

Æ

Luminosity:(1�

4)�

1032cm�

2s�

1

Æ

IntergratedLuminosity:(1�

4)fb�

1/year

�

Expecteddatasample(startearly2003):

Æ

2�

109J= /fb�

1,

107 ;;/fb�

1,

5�

105Ds Ds /fb�

1

�

Physicscanbeachieved:

Æ

Precisiondecayconstants,absoluteBR......

Æ

TestofQCD(Glueball,Hybrids)......

Æ

Mixing,CPviolationincharm,�decays......



37

'&

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FutureOutlookofExperimentalHEP

�

HEPexperimentsate+e�

Colliders:

Æ

B-factories:BABARatPEP-IIandBELLEatKEK-B

Æ

C-factories:CLEO-catCESRetc

�

HEPexperimentsatppandppColliders:

Æ

p p:CDFandD0atTevetron

Æ

pp:ATLASandCMSatLHC

�

NeutrinoExperiments:

Æ

Super-K,Minos,SNOetc



experiment - university of houston

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