# Presentation: 672176

## Boson Pair Production +  Triple Gauge Couplings

- <footer>

- <date/time>

- 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

## 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, 1997

## Characterized by effective Lagrangian

CP Conserving SM  Parameters:                                           
    g
Static Properties  

- CP Conserving SM  Parameters:                                           
-     g
- Static Properties

- Non-SM WWZ/WW Interaction

- QeW =e/2  M2W ()

- W=e/2  MW

- February 24, 1997

## Effect of non-SM Couplings

- Cross section increases especially for High ET bosons (W/Z/).
- Unitarity Violation avoided. e.g.:

- WW Production

-  is a form factor scale

- PT(W)

- (WW)

- February 24, 1997

## 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

- Photon ID

- GeV

- February 24, 1997

## 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**

- Preliminary

- February 24, 1997

-    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.

**CDF**

- Data subsample.

- February 24, 1997

## 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.

- February 24,1997

##  WW A.C. Limits

**D0**

- Tightest WWg Coupling Limits available.  95% CL.
- U(1)EM point excluded.

***Combined limits: together with***
***an earlier 14 pb******-1****** ******publication***
- PRL **75**, 1034 (1995)

- Require 3-body Transverse Mass > 90 GeV/c2
- for PT fit.

- February 24, 1997

## 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:
- 
- eR(,e)>0.5
- |Mee-MZ|  <15 GeV/c2
- |ETrecoil|<40 GeV

- Event ID

- |<1

- Nearest Lepton

- e

- eee

- 

- February 24, 1997

## 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”

- _Background_

**D0**

**CDF**

- _Candidates_

- _Results_

- @95% C.L.

- =1000 GeV

- Preliminary

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

- February 24, 1997

## 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

- Lepton ID

- Jet Selection

- February 24, 1997

##           WW/WZ Production 

- Effect of PT(W) Cut:
- Reduced Acceptance.
- Reduced Sensitivity            M(WW)>450 GeV/c2

**CDF**

- 95% CL  Limits

- =1000 GeV

- Preliminary

- February 24, 1997

## WW/WZ  -> ejj 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

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

- February 24,1997

## WW/WZ->ejj Production

**Limits from  fit to P****T****(e********)**

***Limits will superceed results of Run Ia***
***analysis ****[PRL**** 77****, 3303 (1996)]*

**Another   contour indicates W couples to Z**

******=2 TeV**

**D0**

- February 24, 1997

## 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 h2V
-    CP Conserving h3V and  h4V
- Transition Moments

- February 24, 1997

## 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

- Photon ID

- ee and 

- 

- ee and 

- tight

- loose

- February 24, 1997

## Zg 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

**CDF**

- Preliminary

- February 24, 1997

## 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

- M(ee)

- M(ee)

- October 8, 1996

## 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

**D0**

- February 24,1997

## Limits on Anomalous ZV Couplings

**Run Ia (ee,********,********):**

**Run Ib (ee,********):**

**D0**

- 95% CL  Limits

- Tightest ZV Limits Available

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

- February 24, 997

## 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, 1997

## ZZ Candidate from CDF

- Three Central Muons. One muon inferred from a high-PT track.
- Expected 0.1 event.
- Backgrounds?

- February 24, 1997

## WZ Candidate from CDF

- Approx. 1 such event expected.
- Three high ET electrons and Missing Transverse energy.
- Backgrounds?

- February 24, 1997

## Summary

- 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.

- February 24, 1997

## LEP vs Tevatron

- LEP experiments use 3 variables to parameterize WWV anomalous couplings.

- 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, 1997

## Z Candidate from D0

- 

- 

- 

- 

- 

- Run: 58766
- Event: 10750
- Recorded: 01/09/93
**E****T******** = 67.9 GeV**
**E****T****  = 56.6 GeV**
************

- February 24,1997

## Z(ee) Candidate from D0

- Run 79096, Event 15782, recorded 05/22/94
**E****T******** = 73.3 GeV, M****ee**** = 89.4 GeV, **
**M****ee******** = 200.3 GeV**

- 

- e1

- e2

- 

- e1

- October 8, 1996

- Storage

- February 24, 1997

## 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

- Photon ID

- Channel
- in progress

- GeV

- February 24, 1997