Search for ZZ and ZW productions in ppbar collisions for winter 2004

 
S. Cabrera, J.Deng, A.Goshaw, C.Hays, Y,Huang, M.Kruse

[CDF ONLY : analysis details can be found in CDF-6920]


Abstract
We present a search for ZZ and ZW productions in ppbar collisions at s1/2 = 1.96 TeV through the leptonic decay channels ZZ→ llll,  ZZ→ llνν and ZW→ lllν. In a 194 pb-1 data sample collected at the collider detector at Fermilab, 3 ZZ and ZW candidates are found with an expected standard model background of 1.0 ± 0.2 events. We set a 95% confidence level upper limit of result, compared to the standard model predication of 5.0 ± 0.4 pb.

 

Event selections
Corresponding to the three decay modes ZZ→ llll,  ZZ→ llνν and ZW→ lllν, we select three types of events

  1. Four lepton events l1+, l1- , l2+, l2- (l=e, µ):
  2. Three lepton events l1+, l1-, l2+ (l=e, µ):
  3. Two lepton events l+, l- (l=e, µ):

The electrons, muons, and jets are:

  1. Electrons: ET > 20 GeV,  |η|<1.1 for electrons in central calorimeter and 1.2<|η|<2.5 for electrons in plug calorimeters.
  2. Muons:     PT > 20 GeV/c, |η| less than about 1.0
  3. Jets:          ET > 15 GeV, |η|<2.5

 

Summary of data, and expected signal and background

Source l1+, l1- , l2+, l2- l1+, l1-, l2+ l+, l- Combined
ZZ 0.06 ± 0.01 0.13 ± 0.01 0.69 ± 0.11 0.88 ± 0.13
ZW   0.78 ± 0.06 0.65 ± 0.10 1.43 ± 0.16
Total Signal 0.06 ± 0.01 0.91 ± 0.07 1.34 ± 0.21 2.31± 0.29
WW     0.40 ± 0.07 0.40 ± 0.07
Fake 0.01 ± 0.02 0.07 ± 0.06 0.21 ± 0.12 0.29 ± 0.16
Drell Yan     0.31 ± 0.17 0.31 ± 0.17
Top     0.02 ± 0.01 0.02 ± 0.01
Total Background 0.01 ± 0.02 0.07 ± 0.06 0.94 ± 0.22 1.02 ± 0.24
Expect S.+B. 0.07 ± 0.02 0.98 ± 0.09 2.28 ± 0.35 3.33 ± 0.42
Data 0 0 3 3

 


Kinematic Distributions

dR(l1,l2)
eps
lepton Eta
eps


Event Displays
Run 160533, Evt 162027 (ee)
 Run 161722, Evt 330583 (µµ)
 Run 167053, Evt 12891960 (ee)
cot.eps lego.eps 
cot.eps lego.eps 
cot.eps lego.eps 



Last Updated on February 09, 2005 by Y. Huang