Boson Pair Production + Triple Gauge Couplings

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.


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


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


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


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


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. ...


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.


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


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


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


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


(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


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


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

( )

( )


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


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)


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. .


(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


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.


2233

ZZ Candidate from CDF

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

Expected 0.1 event. Backgrounds?


2244

WZ Candidate from CDF

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

Transverse energy. Backgrounds?


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


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.


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


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}


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

Boson Pair Production + Triple Gauge Couplings

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