First Observation of WZ Production and Search for ZZ

First Observation of W^±Z⁰ Production and Search for Z⁰Z⁰ in 1.1 fb^-1 of ppbar Collisions at √s=1.96 TeV

Authors:
Blessed: October 25, 2006
Data: Run II, 1.1/fb
Note: Description with more details

Introduction

We describe searches for W^±Z⁰ and Z⁰Z⁰ production using 1.1 fb^-1 of integrated luminosity. The W^±Z⁰ search is for a final state with 3 e,&mu leptons and missing tranverse energy (MET) from the unobserved neutrino in lepton decay of the W^± boson. The Z⁰Z⁰ search is for four final state e,&mu leptons from leptonic decay of each Z⁰ boson. At tree level, the W^±Z⁰ final state has the s-channel (left) and t-channel (right) contributions shown in these diagrams:

The s-channel diagram provides sensitivity to the WWZ vertex coupling. The W^±Z⁰ final state is unique among the triple gauge coupling (TGC) final states, providing access to this coupling separately from the WW&gamma coupling. The Z⁰Z⁰ final state involves ZZ&gamma and ZZZ TGCs which are absent in the Standard Model. Both W^±Z⁰ and Z⁰Z⁰ final states in fully leptonic decay are rare but clean experimental signatures that are sensitve to new physics contributions.

Summary of Results

W^±Z⁰ Search Analysis

TEX or GIF Signal and background expectations and observed events in the signal region for the W^±Z⁰ search analysis.

We measure:

consistent with the NLO cross section value of 3.7 ± 0.3 pb.

Z⁰Z⁰ Search Analysis

TEX or GIF Signal and background expectations and observed events in the signal region for the Z⁰Z⁰ search analysis.

We measure:

consistent with the NLO cross section value of 1.4 ± 0.1 pb.

EPS or JPG Summary of single boson and diboson cross section measurements at the Tevatron at the time of WZ/ZZ blessing, including our results.

Analysis Methods

Selection

Signal and Control Regions

EPS or JPG MET vs. Dilepton Mass showing signal and control regions. Box plot of expected signal and backgrounds also shown.

Tables and Plots for Regions in W^±Z⁰ Search Analysis

Summary of Control Region Results

EPS or GIF Summary of Dilepton and Trilepton Control Regions

N-1 Dilepton Invariant Mass Distributions


JPG or EPS MET distribution in Z mass	JPG or EPS MET distribution (log scale) in Z mass

N-1 Missing Transverse Energy (MET) for Signal and Low MET Regions


JPG or EPS MET distribution in Z mass	JPG or EPS MET distribution (log scale) in Z mass

Low MET Region

TEX or GIF Expectations and observed events in the Low MET region for the W^±Z⁰ search analysis.


JPG or EPS Trilepton flavor types for the Low MET region	JPG or EPS Transverse mass of non-Z lepton and MET for the Low MET region

JPG or EPS Trilepton mass for the Low MET region	JPG or EPS Angle between MET and nearest lepton or jet for the Low MET region

JPG or EPS Leading lepton transverse momentum for the Low MET region	JPG or EPS Sub-leading lepton transverse momentum for the Low MET region

JPG or EPS Sub-Sub-Leading lepton transverse momentum for the Low MET region	JPG or EPS Z transverse momentum for the Low MET region

Z Veto Region

TEX or GIF Expectations and observed events in the Z veto region for the W^±Z⁰ search analysis.


JPG or EPS Trilepton flavor types for the Z veto region	JPG or EPS Transverse mass of non-Z lepton and MET for the Z veto region

JPG or EPS Trilepton mass for the Z veto region	JPG or EPS Angle between MET and nearest lepton or jet for the Z veto region

JPG or EPS Leading lepton transverse momentum for the Z veto region	JPG or EPS Sub-leading lepton transverse momentum for the Z veto region

JPG or EPS Sub-Sub-Leading lepton transverse momentum for the Z veto region	JPG or EPS Z transverse momentum for the Z veto region

Signal Region

TEX or GIF Expectations and observed events in the Signal region for the W^±Z⁰ search analysis.


JPG or EPS Trilepton flavor types for the Signal region	JPG or EPS Transverse mass of non-Z lepton and MET for the Signal region

JPG or EPS Trilepton mass for the Signal region	JPG or EPS Angle between MET and nearest lepton or jet for the Signal region

JPG or EPS Leading lepton transverse momentum for the Signal region	JPG or EPS Sub-leading lepton transverse momentum for the Signal region

JPG or EPS Sub-Sub-Leading lepton transverse momentum for the Signal region	JPG or EPS Z transverse momentum for the Signal region