11 February 24, 1February 24, 1997997

Boson Pair Production + Triple Gauge CouplingsBoson Pair Production + Triple Gauge Couplings

Results from the Tevatron

San Miniato - April, 1997

WW/WWZ Couplings

W Production

WW/WZ Production

ZZ/Z Couplings

Z Production

Prospects for Run II

Summary Tom Diehl for the D0 and CDF Collaborations

February 24, 1February 24, 1997997

22

Standard Model Gauge Boson Interactions

Self-interactions are direct consequence of the non-abelian SU(2)L x U(1)Y gauge symmetry.

SM makes specific predictions. Cancellation of t and u -channel by s-channel

amplitude removes tree-level unitarity violation.

February 24, 1February 24, 1997997

33

Characterized by effective Lagrangian

CP Conserving SM Parameters:

g

Static Properties

Non-SM WWZ/WW Interaction

QeW =e/2 M2

W ()

W=e/2 MW

L W W V W V W

W W V

W W V

WWV WWV V†

V

V†

/ ( )

/

†

†

g g

MW

1

2

February 24, 1February 24, 1997997

44

Effect of non-SM Couplings

Cross section increases especially for High ET bosons (W/Z/).

Unitarity Violation avoided. e.g.:

WW Production

( )( / )

ss n

1 2

n 2 for WW ,WWZ

is a form factor

scale

PT(W)(WW)

n ZZ Z3 4, for and

February 24, 1February 24, 1997997

55

W Selection @ CDF + DO

CDF (67pb-1)

|e|<1.1 ||<0.6

||<1.1

GeV

D0 (93 pb-1)

|e|<1.1 ||<1.0

1.5<|e|<2.5

Same || as electron

Lepton ID

E T 20 E T 25E T 25

R l 0 7.

Photon ID

E T 15PT15

E T 7 E T10

E T 20 PT 20

GeV

February 24, 1February 24, 1997997

66

W Production

109 Candidates (75 e 34 )

Background: (W+jets,Z,W->) =

Signal vs. SM SM Signal = Candidates-Backgd

= 82.6 events

Anomalous Coupling

Limits: =1.5 TeV

@95% C.L.

CDF

26 4

2 7

.

.

753 8 0. .

18 2 0 0

0 7 0 7 0

. . ( )

. . ( )

Preliminary

February 24, 1February 24, 1997997

77

W Radiation Zero SM has “amplitude zero” at

where is angle between incoming quark and photon in the W rest frame (W polarization -> 73% correct rest frame).

Radiative events are background so increase R cut.

CDFcos( )*

1

3 *

Data subsample.

February 24,19February 24,199797

88

W Production

= 1.5 TeV

D0 127 Candidates (57 e 70 )

Background: (W+jets, Z) = events.

Signal vs. SM SM: xBR = pb D0: xBR = pb.

43 5

12 5 10. .113 151 5

1 7. ...

February 24, 1February 24, 1997997

99

WW A.C. LimitsD0

Tightest WWg Coupling Limits available. 95% CL.

U(1)EM point excluded.

0 93 0 94

0 31 0

. . (

. .

= 0)

29 ( = 0)

= 1.5 TeV

Combined limits: together with

an earlier 14 pb-1 publicationPRL 75, 1034

(1995)

Require 3-body Transverse Mass

> 90 GeV/c2

for PT fit.

February 24, 1February 24, 1997997

1100

WW->dileptons @ D0 and CDF

CDF (108pb-1)

|e|<1.1 ||<0.6

75<Mee or <105 GeV/c2

Veto events w/ jet of ET > 10 GeV

D0 (79pb-1)

|e|<1.1 1.5<|e|<2.5

ee:

e:

eR(,e)>0.5 |Mee-MZ| <15 GeV/c2

|ETrecoil|<40 GeV

E T 25 E Tl 20 E T 25E T

e 25 20,

Event ID

if GeV E T 50

PT15

|<1

E Te 25

E Tcal 25

PT 25 20, E T

30

E T 20Nearest Lepton

( , ) E lT 20 160 > ( , )E lT 20

e eee

February 24, 1February 24, 1997997

1111

WW-> dilepton Results

3 e, 2 ee, 0

Drell-Yan, fake leptons

events

“Evidence for WW

Production”

=1000 GeV

2 e, 1 ee, 1

Drell-Yan, W,t-tbar, fake leptons

events

“Cross Section consistent w/ SM”

12 0 3. .

Background

D0CDF

2 6 0 4. .

( ) . ...WW

10 2 165 16 5 pb

Candidates

Results

11 13

0 8 0 9

. .

. .

@95% C.L.

| | .

| |

12

1.0

=1000 GeV

( )WW X 43 pb (95%CL)

Preliminary

Fermilab-Pub-96/311-E To be published in PRL

February 24, 1February 24, 1997997

1122

WW/WZ Semi Leptonic Decay Modes @ CDF + D0

CDF (110pb-1)

|e|<1.1 ||<0.6

MT(e)>40 GeV/c2

2+ Jets 0.4 cone

GeV 60<Mjj<110 GeV/c2

ET(jj)>200 GeV

D0 (96pb-1)

|e|<1.1 1.5<|e|<2.5

MT(e)>40 GeV/c2

2+ Jets 0.5 cone

GeV 50<Mjj<110 GeV/c2

|ET(jj)-ET(e)| < 40 GeV

E T 20 E Tl 20 E T 25 E

T

e 25

Lepton ID

Jet Selection

E Tj 20E T

j 25

February 24, 1February 24, 1997997

1133

WW/WZ Production

Effect of PT(W) Cut: Reduced Acceptance. Reduced Sensitivity

M(WW)>450 GeV/c2

CDF

95% CL Limits

=1000 GeV

Z

Z

0 49 0

0 35 0 32

. .

. .

54

=2000 GeV

0 67 0

051 051

. .

. .

85

Preliminary

February 24,19February 24,199797

(Updated From Greg Landsbe(Updated From Greg Landsberg's Wine&Cheese Talk - 9/6/rg's Wine&Cheese Talk - 9/6/96, Fermilab)96, Fermilab)

1144

WW/WZ -> ejj Production

Run Ib, 82.3 pb

SM(WW) = 9.5 1.0 pb (BR = 1.4 pb)

SM(WZ) = 2.5 0.3 pb (BR = 0.2 pb)

D0

399 Candidates Background Source:

W+2 or more jets, t-tbar

= 387+-38 events

SM Pred = 18+-3 (WW+WZ) events

Preliminary

February 24, 1February 24, 1997997

1155

WW/WZ->ejj Production

Limits from fit to PT(e)

033 036

043 059

. .

. .

Z

Z

Limits will superceed results of Run Iaanalysis [PRL 77, 3303 (1996)]

Another contour indicates W couples to Z

=2 TeV

D0

February 24, 1February 24, 1997997

1166

ZZ/Z Interaction In SM all are couplings equal to zero Non-SM Characterized by an

effective Lagrangian w/ 8 coupling parameters.

CP Violating h1V and h2

V

CP Conserving h3V and h4

V

Transition Moments

de k

Mh h

e k

Mh h

ZZ

Z Z

ZZ

Z Z

T

T

2

2

2

3 30 40

2

3 10 20

( )

( )

February 24, 1February 24, 1997997

1177

Z Selection @ CDF + DO

CDF (67pb-1)

|e1|<1.1 ||<0.6

|e2|<4.2 ||<1.2

Same || as Wg

DO (96,87,14) pb-1

(ee,, |e| as before,

|| <1, || < 1,2.4

Neutrino Channel

No Jets (ET>15 GeV)

Same || as Wg

Lepton ID

ETe 25

Photon ID

R l 0 7.ET 7 GeV ET

10 40, GeV

E Te1 20 PT 20

E Te2 20 15 10 , ,

P

P

T

T

GeV / c

GeV / c

15 10

15 2

,

,

ET 40 GeV

ee and ee and

tight

loose

February 24, 1February 24, 1997997

1188

Zg ResultsZg Results 31 Candidates (18 ee, 13 )

Background (Z+jets) = events Signal vs. SM

SM signal = 24.9 events expected Candidates-Background = 29.6 events

A.C. Limits:

assuming only one

coupling at a time is non-zero

16 16

0 4 0 4

30 10

40 20

. ( ) .

. ( ) .

h h

h h

Z Z

Z Z

14 0 3. .

hn0 similar

CDF

500 GeV

Preliminary

October 8, 199October 8, 19966

1199

Z(ee,) Candidates vs. SM

29 Candidates (14 ee, 15 )

Background (Z+jets, W channel only)

Signal vs. SM SM signal = 29.1 Z events expected. Candidates-Background = 23.6 events.

D0

Preliminary

54 10. . events

E eeT ( )

M(ee)

M(ee)

February 24,19February 24,199797

2200

Z Candidates vs. SM

4 Candidates Background (W->e, Brems.)

SM signal = events expected.

Fermilab-Pub-97/047-E accepted by PRL Fermilab-Pub-97/088-E submitted to PRD

58 10. . events

D0

18 0 2. .

February 24, 9February 24, 99797

(From Greg Landsberg's Wine(From Greg Landsberg's Wine&Cheese Talk - 9/6/96, Fermil&Cheese Talk - 9/6/96, Fermilab)ab)

2211

Limits on Anomalous ZV Couplings

Run Ia (ee,,):

Run Ib (ee,):

| ( )| . | ( )| .h h h hZ Z Z Z30 10 40 20136 0 26

500 GeV

750 GeV 500 GeV

| ( )| .

| ( )| .

h h

h h

Z Z

Z Z

30 10

40 20

0 78

019

| ( )| .

| ( )| .

h h

h h

Z Z

Z Z

30 10

40 20

0 44

0 06

D0

hn0 similar

95% CL Limits

Tightest ZV Limits Available

February 24, 1February 24, 1997997

2222

Prospects for Run 2

Tevatron and detector upgrades provide 2 fb-1 data samples.

Quantitative Expectations Factor of 20X in luminosity provides ~ 2.5X

improvement in A.C. limit. (at fixed form factor scale). Numbers of events (CDF + D0) estimate.

W _> l ~ 3000

Z _> ee( ~ 700

WW _> ll ~ 100

WZ _> lll ~ 30

ZZ_> e’s and ’s a few

Qualitative Expectations Wg and WZ radiation zero. Tevatron Studies probe theoretical

expectations for A.C.’s.

February 24, 1February 24, 1997997

2233

ZZ Candidate from CDF

Three Central Muons. One muon inferred from a high-PT track.

Expected 0.1 event. Backgrounds?

February 24, 1February 24, 1997997

2244

WZ Candidate from CDF

Approx. 1 such event expected. Three high ET electrons and Missing

Transverse energy. Backgrounds?

February 24, 1February 24, 1997997

2255

SummarySummary D0 + CDF study W,WW,WZ, and Z

diboson final states with a rich variety of techniques.

WW, WWZ, ZZ, Z interactions appear to be those of Standard Model. WWg and WWZ vertices observed. Hint of Radiation Zero in Wg (CDF). (CDF). Limits on anomalous WWV and ZVg

Couplings. Tightest Are:ZV: =750 GeV limits from D0.

WWV: =2000 GeV limits from D0 and CDF (comparable).

Run II Detector and Lum. Upgrades.

( ) . ...WW

10 2 165 16 5 pb

February 24, 1February 24, 1997997

2266

LEP vs TevatronLEP vs Tevatron

LEP experiments use 3 variables to parameterize WWV anomalous couplings.

g

g

ZW

WZ

W

W Z

12

12

cos

cos

LEP sensitivity highest to W. Limits on W correspond to limits on .

Limits on W correspond to limits on

if B and W are fixed to zero.

February 24,19February 24,199797

2277

Z Candidate from D0

Run: 58766Run: 58766Event: 10750Event: 10750Recorded: 01/09/93Recorded: 01/09/93ET

= 67.9 GeVET = 56.6 GeV

October 8, 199October 8, 19966

2288

Z(ee) Candidate from D0

Run 79096, Event 15782, recorded 05/22/94Run 79096, Event 15782, recorded 05/22/94

ET = 73.3 GeV, Mee = 89.4 GeV,

Mee = 200.3 GeV

ee11

ee22

ee11

February 24, 1February 24, 1997997

2299

Storage

Analysis (pb-1) Scale Limits

D0 WW(dilepton)

73 1.0 -2.6<<2.6-2.1<<2.1

D0 WW(ejetjet)

96 2.0 -2.6<<2.6-2.1<<2.1

D0 W 96 1.5 -2.6<<2.6-2.1<<2.1

Z():

| | . ,| | .,

,

,

,

30 10 40 200 8 0 2

Z Z

h h Z(ee):

| | . ,| | .,

,

,

,

30 10 40 200 9 0 2

Z Z

h h

@ 95% CL}

February 24, 1February 24, 1997997

3300

Z Selection @ CDF + DO

CDF (67pb-1)

|e1|<1.1 ||<0.6

|e2|<4.2 ||<1.2

||<1.1

GeV

DO (73 pb-1)

|e|<1.1

1.5<|e|<2.5

Same || as electron

Lepton ID

E T 25

R l 0 7.

Photon ID

E T 7 E T10

E Te1 20 PT 20

E Te2 20 15 10 , ,

Channel

in progress

GeV