Run 2 at CDF: results from top quark and electroweak ...mkruse/talks/users_meeting_2004.pdf ·...

Run 2 at CDF:results from top quark and

electroweak measurements, andnew physics searches

Mark KruseDuke University

For the CDF Collaboration

FNAL 2004 Users’ Annual Meeting

2 June 2004

FNAL Users’ Annual Meeting 2004

Outline

� Introduction

� CDF detector and performance in Run II

� W’s, Z’s, and other Electroweak measurements

� Top quark studies

� Higgs and new physics searches

� Summary

Mark Kruse, Duke University, 2 June 2004 1


Introduction

10-14

10-13

10-12

10-11

10-10

10-9

10-8

100 120 140 160 180 200

Higgs mass (GeV/c2)

Cro

ss s

ectio

n (b

arns

)

tt

W l ν

Z ll

Events Producedper 100 pb

−1

WW

250,000

25,000

WZ

1300700

200

20 (for M = 120)

ZH + WH

Many new physics possibilities

single t 300

High-PT physics at CDF now in high gear � exciting next few years

� W’s, Z’s: Large cross sections

� high statistics

� precision measurements

� Top: Cross section � 7 pb

� now entering phase ofhighly anticipated precisionmeasurements

� Dibosons: σ’s � few pb

� beginning program ofimportant SM tests

� Higgs, new physics:foundations built from theabove analyses crucial foroptimal searches


FN

AL

Use

rs’A

nnua

lMee

ting

2004

The

CD

FRu

nII

Det

ecto

r ��

SV

XII

+ IS

L

HA

D c

al

Mu

on

ch

amb

ers/

scin

tilla

tors

EM

cal

CO

T

�

De

tec

torp

erfo

rmin

gw

ell

�

Da

tata

king

effi

cie

ncy

�

80%

�

Rec

ent

CD

Fa

naly

ses

ba

sed

on

�

200

pb

�

1(M

ar/

02-A

ug/0

3)

��

60pb

�

1o

nta

pe

sinc

e

�

Exp

ec

tano

the

r

�

400

pb�

1

with

inne

xtye

ar

�

Ne

win

Run

II:

�

Fro

nt-e

ndD

AQ

,Trig

ge

rsys

tem

(L1

trac

k,L2

disp

lac

ed

trac

k)

�

Tra

cki

ngsy

ste

m(8

laye

rso

fSio

utto

�η��

2�

0,C

OT)

�

Forw

ard

ca

lorim

ete

rs(1�

0 �

�η

��

3�

6)

�

Exte

nde

dm

uon

cov

era

ge

(out

to

�η

��

1�

5)

�

Run

2up

gra

de

sg

rea

tlye

xte

ndp

hysic

sre

ac

h

Ma

rkKr

use

,Duk

eU

nive

rsity

,2Ju

ne20

043


W and Z cross-sections

)2 (GeV/cµµM40 50 60 70 80 90 100 110 120 130

2E

vts

/ GeV

/c

0

20

40

60

80

100

120

140

160

180

)2 (GeV/cµµM40 50 60 70 80 90 100 110 120 130

2E

vts

/ GeV

/c

0

20

40

60

80

100

120

140

160

180Central-Central

DATA (1371)µµ→Z

MCµµ→Z CDF Run II Preliminary

-1 L dt = 72.0 pb∫

� Precision measurements done using W and Z leptonic decays

� Yardstick for validation of all high-PT lepton analyses

� Important for calibration of energy/momentum scales

CDF Run 2 measurement (pb) SM value

σ � BR � W � � ν � 2777 � 10 � stat � � 52 � syst � � 167 � lum � 2690 � 50

σ � BR � Z � � � � 254 � 3 � 3 � 3 � stat � � 4 � 3 � syst � � 15 � 3 � lum � 252 � 5



W and Z cross-sections (cont.)

10-1

1

0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2Ecm (TeV)

σ ×

Br

(nb)

σ×Br(W→lν)

σ×Br(Z→l+l-)CDF II (plug e)

CDF II (e+µ)

CDF I (e)

DO I (e)

CDF (630)

UA1 (µ)

UA2 (e)

NLO theory curves:Martin, Roberts, Stirling, Thorne

� W/Z cross-sections, and related quantities, consistent withcalculations

� Full updates with all available data coming soon



Diboson Production

q’

q

/Z*γ

-W

+W

q’

q

-W

+W

q’

q

W

Z

W

q’

q

Z

W

q’

q

/Z*γ

Z

Z

q’

q

Z

Z

� Direct test of triple gauge boson couplings

� Enhanced W/Z and lepton PT spectra � Anomalouscouplings

� We have measured production cross-sections for:Wγ, Zγ, WW , WZ, ZZ

using the leptonic decays of the W and Z

� Studies of anomalous couplings now in progress

� Provides an important foundation for Higgs searches



Diboson Results: W � Z γ

(GeV)γTE

0 10 20 30 40 50 60 70

Nu

mb

er o

f E

ven

ts /

(7 G

eV)

10-1

1

10

102

(GeV)γTE

0 10 20 30 40 50 60 70

Nu

mb

er o

f E

ven

ts /

(7 G

eV)

10-1

1

10

102 CDF Data

γν l→γWW + jet

γZγντ

0 10 20 30 40 50 60 70

10-1

1

10

CDF Data

γ ll →γZ

Z + jet

(GeV)γTE

Nu

mb

er o

f E

ven

ts/(

7GeV

)

0 10 20 30 40 50 60 70

10-1

1

10

� Data well described over large range of photon ET ’s

Run 2 measurement (EγT � 7 GeV) (pb) SM value

σ � W γ �� BR � W � � ν � 19� 7 � 1� 7 stat � 2� 0 syst � 1� 1 lum 19� 3 � 1� 4

σ � Zγ �� BR � Z � � � � 5� 3 � 0� 6 stat � 0� 3 syst � 0� 3 lum 5� 4 � 0� 3

� Next, with more data, and with WW , test SM couplings



Diboson Results: WW , WZ, ZZ

� Use leptonic decays of the vector bosons � high-PT e � µ’s, missing ET

σ (pb) Observe Background Measured σ (pb)

WW 12.5 17 (TT) 4.8 � 0.7 14 � 3 � 5� 6

� 4� 9 � stat � � 1 � 6 � syst � � 0 � 9 � lum �

39 (TL) 16 � 1 19 � 4 � 5 � 1 � stat � � 3 � 5 � syst � � 1 � 2

WZ + ZZ 3.8 + 1.4 4 2.3 � 0.4 � 13 � 9 at 95% CL

� Evidence for WW in Run 1 nowconfirmed in Run 2

� WZ and ZZ not yet observed,but some interesting events.....

� next; better optimize, useadditional decay channels(including Z � bb̄)



WW eνµν candidate

η

-4-3

-2-1

01

23

4

φ

0100

200300

TE

050

100150

��

! " � #%$ & &'( )* + , -. / ! " � # $ 0 )( 1* + , -. /2 � � $ & 3 0( 3* + ,

45! $ 6 3( 6* + , /7 " 45! # $ &( 3

87 " 45! 9: + ;<= > # $ &( ' / 87 " � 9 � # $ '( ? /@ ; + >A > BDC E > B : + " � � 9 �� #$ &F G



W eν charge asymmetry

|η| 0 0.5 1 1.5 2 2.5

Co

rrec

ted

Asy

mm

etry

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3-1CDF-II Preliminary, 170 pb

25 < E < 35 GeV e

T

RESBOS CTEQ6.1M(F. Landry, R. Brock, P.M. Nadolsky, C.P. Yuan,

Phys.Rev.D67:073016,2003)40 extreme pdfsets

|η|0 0.5 1 1.5 2 2.5

Co

rrec

ted

Asy

mm

etry

-0.3

-0.2

-0.1

0

0.1

0.2

0.3 -1CDF-II Preliminary, 170 pb

35 < E < 45 GeV e

T

RESBOS CTEQ6.1M(F. Landry, R. Brock, P.M. Nadolsky, C.P. Yuan,

Phys.Rev.D67:073016,2003)

40 extreme pdfsets

� Provides important constraints to PDF’s

� Higher u momentum � W � boosted in p directionW � boosted in p̄ direction

� Forward electron identification crucial � use Silicon

� Indication of higher PT data having more PDF discriminationthan prediction (CTEQ6.1 with RESBOS NLO)



Lots of other electroweak activity.....

102

FB

A

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

102

FB

A

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

40 60 100 200 300 600

MC-e+ e→* γZ/band includes

several theoreticalcalculations

StatisticalTotal

(GeV)eeM

corrected assuming SMFBA couplings fitsFBand using A

� Measurement of forward-backward asymmetry of Z � γ � � e � e �

� Direct probe of Z, γ couplings

� Deviations could signifyinterference from new physics

� � 2σ effect seen in Run 1

� High mass reach uniqueto Tevatron

� In Run 2 (72pb

� 1)see agreement with SM

� W/Z cross-sections using tau leptons

� σ � W � � BR � W � τν �� 2 � 62 � 0 � 07 � stat � � 0 � 21 � syst � � 0 � 16 � lum � (72pb � 1)

� Provides baseline for all analyses using tau’s

� W mass: Requires meticulous understanding of detector responses,resolutions, and backgrounds. Preliminary results ready � August



Measuring the Top Quark

� The top quark remains themost intriguing particle wehave discovered

� Large Mass � intimate con-nection with EWSB ?

� Everything we know abouttop is based on � 100 events

� Main Run 2 priority to mea-sure as many top quarkproperties, in as many ways,and as best we can, not onlyas a test of the SM, but to ex-ploit the top quark potentialto lead us to new physics

tb

q’

l+

l-

q’

p

tX

b

W

W

νq

q

ν

p

+

-

,

,

SM

Decay modes

Branching ratios

CKM matrix element Vtb| |

Rare decayst -> Zc / c , t -> WZb , ...γ

+Non-SM decays~

W helicity

-t -> H , t -> t , ...

Top Mass

Top spin polarization

Production Cross Section

Resonance production ?

Production kinematics

New Physics ?

� The Tevatron is the only place to do this for several more years



Top Quark ProductionTop quarks can be produced:

In pairs via the stronginteraction

singly via the electroweakinteraction

t

t

q

q

t

t

g

g

t

t

g

g

t

t

g

g

��

��

�

� � � �

��

�

��

σ � 7 pb (30% increase over Run 1)Many Run 2 measurements

σ � 3 pbNot (yet) observed



Top Decays

t

t–

q

q–

b

b–

W+

W-

l+ , q–

νl , q,

l- , q,

ν–

l , q–

BR(W � � ν) = 3 / 9BR(W � qq̄� ) = 6 / 9

Measurements are made using distinct decay channels:

� Dilepton: 2 high-PT e’s or µ’s, 2 high-ET jets, large Missing ET

BR = 5%

� Tau-dilepton: 1 e or µ, 1 hadronic τ, 2 high-ET jets, large Missing ET

BR = 5%

� Lepton + Jets: 1 high-PT e or µ, 4 jets (2 b’s), large Missing ET

BR = 30%

� All-hadronic: 6 jets (2 b’s): BR = 44%



Top expectations in Run 2

σ (pb) @ 2 TeV Events produced per 200 pb � 1

qq̄ � tt̄ (90%) 70 (dilepton)

6� 7 � 0� 3 400 (lepton + jets)

gg � tt̄ (10%) 600 (all-hadronic)

qq̄ � W � � tb (30%)

2� 9 � 0� 3 130 (lepton + jets)

qb � q� t (70%)

� Detection efficiencies �

Observe 10 - 20% of events produced

� 10x current luminosity will make a huge difference



Heavy Flavour tagging

prompt tracks z

y

x

xyL

tracksdisplaced

Primary vertex

vertex

0d

Secondary

b

µe or in jet

� Lepton + jets and all-hadronic decay channels rely heavily onidentification of B hadron decays to reduce backgrounds

Measure secondary vertex:B’s travel � 3mm before decay

Identify low-PT muon in jet:BR(b � � νc) � 20%

Top event tag efficiency � 55%

False tag rate � 0 � 5%

Relies on excellent Si performance

Top event tag efficiency � 15%

False tag rate � 4%



Run 2 Top Cross-sections

Missing Transverse Energy (GeV)0 20 40 60 80 100 120 140

, nea

rest

l o

r je

t) (

deg

)T

E (φ∆

0

20

40

60

80

100

120

140

160

180 Monte Carlott

)-1

CDF II ee data (197 pb

)-1

data (197 pbµµCDF II

)-1

data (197 pbµCDF II e

� Many different avenues taken

� All sensitive to, and test, different as-pects of top production

� E.g. ee � eµ � µµ: cleanest channelmild eµ anomaly seen in Run 1Run 2: expect 4 ee � µµ, 4.5 eµ

Observe:1 ee

3 µµ

9 eµ

� Combine results for best precision

� goal to achieve 10% result after 2 fb

� 1 (also expect � 100 tt̄ � dileptons !)



Top Mass in Run 2

)2 (GeV/cTopMaximum Likelihood M130 140 150 160 170 180 190 200 210 220

)2

Eve

nts

/(10

Gev

/c

0

1

2

3

4

5

6

7MC PredictionSignal ttbar(MC)Backgroud(MC)Data 22 events

)-1CDF Run II Preliminary (162 pb2 = 175GeV/ctopSignal MC : M

Maximum Likelihood Mass

80.2

80.3

80.4

80.5

80.6

130 150 170 190 210

mH [GeV]114 300 1000

mt [GeV]

mW

[G

eV]

Preliminary

68% CL

∆α

LEP1, SLD Data

LEP2, pp− Data

� Precision measurement constrains Higgs sector:

� 1 GeV in Mtop � � 5 GeV in best fit Mhiggs

� Different methods use different assumptionsand event information

� Using b-tagged lepton + jets events

Dynamical Likelihood: Mtop� 177 � 8 � 4� 5

� 5� 0 � stat � � 6 � 2 � syst � GeV � c2

[ Template: Mtop� 174 � 9� 7� 1� 7� 7� 6 � 5GeV � c2 Multivariate: Mtop� 179 � 6� 6� 4� 6� 3� 6 � 8GeV � c2 ]

� From dilepton events: Mtop� 175 � 17 � stat � � 8 � syst � GeV � c2 (126pb � 1)

� c.f. Run 1 CDF + DØ world average:178 � 0 � 4 � 3 GeV � c2

� Near future improvements in simulation,jet energy scale, and finally combiningall information, will give significantimprovements. Longer term goal toachieve ∆Mtop � 3 GeV. Please stand by.....



Top Physics Outlook

80.2

80.3

80.4

80.5

80.6

130 150 170 190 210

mH [GeV]114 300 1000

mt [GeV]

mW

[G

eV]

Preliminary

68% CL

∆α

LEP1, SLD Data

LEP2, pp− Data

� Many other measurements with initial results and in progress:

� Searches for single top: Cross-section a direct test of the Wtb

coupling: Current Run 2 result: � 13 � 7 pb @ 95% CL (combined)

� W helicity

� Measurements of BR’s

� Tau-dilepton channel

� Search for high mass particles decaying to tt̄

� Search for rare decays

� Top quark spin

� We are now entering the first period of precision topmeasurements:anomalies, surprises, could be important clues to massgeneration in the universe, and/or other new physics



Searches for the Higgs

� The Higgs boson is crucial to our understanding of EWSB

� The Standard Model Higgs is used as a benchmark for ourdiscovery potential. Currently:

� MH� 114GeV � c2 (95% CL) (from direct LEP searches)

� MH� 251GeV � c2 (95% CL) (from fit to electroweak data)

� With 5 fb � 1 � can exclude SM Higgs up to � 130GeV � c2

� possibly achieve a 3σ result for MH � 115GeV � c2

� However, there exist many additional Higgs bosons in a varietyof other models, some of which we are more sensitive to

� Many analyses underway at CDF:

� Deep understanding of backgrounds and signal required

� Rely heavily on tools and experience from related analyses

� Some promising ideas emerging to increase sensitivity



SM Higgs Overview

1.0

0.1

100 120 140 160 180 200

gg→H

WH

ZH

Higgs Mass (GeV/c2)

Cro

ss S

ect

ion

(p

b)

s = 1.96 TeVEXCLUDED bb WW

� Production � Decay

� Low mass Higgs searches require associated vector bosonproduction for sensitivity

� For MH� 140 GeV/c2 WW decay mode predominant

� significant gain from gg � H

� E.g. MH � 115: 7 qq̄� � WH � � νbb̄ events produced in 200 pb � 1

MH � 180: 40 gg � H � WW � , 2� 0 with WW � � ν � ν



Run 2 Higgs search using WH � νbb̄

0 50 100 150 200 250 300 350 400 450 5000

2

4

6

8

10

12

0 50 100 150 200 250 300 350 400 450 5000

2

4

6

8

10

12

CDF Run II Preliminary (162 pb-1)

Dijet Mass (GeV/c2)

Ev

en

ts /

10

Ge

V/c

2

mean = 107.85 + 0.25 GeV/c2

width = 18.69 + 0.25 GeV/c2{

W+2jets (Data)WH (m

H=115GeV/c

2)

W+jets and non-WTop, Diboson and Z

0 τ

+

τ−

100×WH

� Utilizes many of the tools and experience from the t t̄

“lepton + jets” analyses

� Select events with:

� 1 high-PT lepton

� Large missing ET

� 2 jets ( � 1 b-tag)

� For MH � 115GeV � c2, expect:

� 0.7 WH � � νbb̄ events

� 60 Background (40% W � h f )

� Observe 62 events

� Use shape of resulting dijet mass distribution to set limits

� Dijet mass resolution and b-tagging efficiency important features



Run 2 Higgs search using H WW �

� ν � ν

llΦ∆0 0.5 1 1.5 2 2.5 3

ll

Φ/d

evt

dN

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5 data

WW →H× 10 WW fakes DY ee

µµ DY ττ DY

WZ ZZ

t t

= 180 GeVHM

-1 = 184 pbintCDF Run II Preliminary, L

� Small branching ratio but extremely clean signal

� Borrows extensively from WW analysis, but with:

� M � � � MH � 2

� ∆φ � � � � � good discriminatorfrom backgrounds � usedistribution to set limits

� For MH � 180GeV � c2, expect:

� 0.2 H � WW events

� 8.9 Background (75% WW)

� Observe 8 events

� Progress being made on ways to extend our sensitivityand include other production and decay mechanisms



Run 2 SM Higgs results

� No evidence for any Higgs yet !

� Limits now better than in Run 1 (H � WW new to Run 2)

� But this is just the beginning....

� Improvements in jet energy resolution and b-tagging

� Combine with searches underway in other decay channels



Search for doubly-charged Higgs

80 90 100 110 120 130 140 1500

0.02

0.04

0.06

0.08

0.1

0.12

0.14

80 90 100 110 120 130 140 1500

0.02

0.04

0.06

0.08

0.1

0.12

0.14

CDF Run 2 Preliminary-1L ~ 240 pb

ee

Theory (R)

Theory (L)µe

µµ

)2 Mass (GeV/c±±H

BR

(p

b)

×C

ross

sec

tio

n

q

q

*γ/0*Z

++H

--H

� Beyond SM, low mass H� � (� 1 TeV)predicted by some models

� H� � decay to same-sign leptons � backgrounds very small

� For MH � � � 120GeV � c2, expect:

� 5 H � �

L � e � e � , µ � µ � events2.5 H � �

L � e � µ � events

� 1.0 background evt (50% ee)

� 0 events observed

� Obtain limits (at 95% CL) of:

� MH � � � 136GeV � c2 (H � �

L � µ � µ � )

� MH � � � 133GeV � c2 (H � �

L � e � e � )

� MH � � � 115GeV � c2 (H � �

L � e � µ � )

� One of several interesting Higgs searches outside the SM



Many other Higgs analyses in progress...

� Other WH and ZH decay channels for low mass Higgs

� WH � WWW , ZH � ZWW with many decay channels

� Charged Higgs searches in SUSY models

� Searches involving tau decays: H � τ � τ � , H� � τ� ν

� Quasi-stable doubly charged Higgs

� Leaving no stone unturned !

� Entering a very interesting phase in Higgs physics(more data) + (more searches) + (more experience) = ???



Many more Run 2 Exotic Physicssearches...

� A myriad of searches underway, many with results from 200pb

� 1,covering a large spectrum of new physics ideas

� Magnetic monopoles

� many SUSY searches

� GMSB: diphoton + Missing Energy

� Z’

� Leptoquarks

� excited leptons

� signatures of extra dimensions

� If it’s there, we should find it !!



Summary

� Run 2 is leading us into a fascinating next few years

Precision measurements from W’s and Z’s

�

Testing the SM with Top and Dibosons

�

Direct and indirect searches for the Higgs and new physics

� A flurry of activity in many areas – already several Run 2 high-PT

analyses either submitted for publication or close to it

� We are exploring what the universe looked like after � 10 � 12s !(and when its temperature was � 1016K)This is largely unknown territory; who knows what we might find...



Backup slides



COT aging

probably need to have some more details ready ??


Run 2 at CDF: results from top quark and electroweak ...mkruse/talks/users_meeting_2004.pdf ·...

Documents

Transcript of Run 2 at CDF: results from top quark and electroweak ...mkruse/talks/users_meeting_2004.pdf ·...