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A Study of Anomalous Production of Z-Bosons with High Transverse Momentum at the Tevatron


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We present a broad search for signatures containing a high transverse  momentum Pt Z boson in 0.94 pb-1 of CDF-II data. In addition to
inclusive production of  Z's with large values of Pt, we investigate  signatures that have a  much smaller Standard Model crossection, and
hence are more sensitive to new phenomena, such as right-handed heavy quarks, technicolor particles, gauginos or squarks, or excited states resulting from  large extra dimensions. The specific channels in   which we search are of the form Z + X + anything and Z + X + Y + anything, where X and  Y can be leptons, photons, missing energy, or large total transverse energy ($H_T$). For each signature we compare the observed Pt(Z) spectra and other distributions with Standard Model expectations.  Alas, we do not see anything striking, yet.


 


Plots and Tables:

Z --> e+e-

Inclusive part.


Inv Mass & Pt(Z)  Invariant mass (left) and transverse momentum (right) for Z --> ee. The two lower plots show the difference between the numbers of expected and observed events divided by the number expected.
A mass cut of 66 < M(ee) < 116 GeV has been applied to the right-hand plot.

 PDF or GIF.
The Bayesian limit on the differential cross section for anomalous Z --> ee production at 95% CL.

PDF or GIF

Signature Part

Z+X+anything

X
Observed
Expected
+\sigma
-\sigma
Lepton
3
1.6
0.3
0.3
Photon
14
12.4
1.5
1.5
Missing Energy
97
85.4
12.3
12.3
Ht
45
36
4.9
5.8

Z+X+Y+anything


X+Y
Observed
Expected
+\sigma
-\sigma
Lepton+Photon
0
0.001
0.001
0.001
Lepton+Missing Energy
1
0.72
0.11
0.11
Lepton+Ht
0
0.16
0.04
0.04
Photon+Missing Energy 1
0.24
0.20
0.20
Photon+Ht 1
0.80
0.34
0.23
Missing Energy+Ht
6
6.6
1.0
1.0







Z --> µ+µ-


Inclusive part.


Invariant mass (left) and transverse momentum (right) for Z --> µ+µ-. The two lower plots show the difference between the numbers of expected and observed events divided by the number expected.
A mass cut of 66 < M(µµ) < 116 GeV has been applied to the right-hand plot.

 PDF or GIF.
The Bayesian limit on the differential cross section for anomalous Z --> µµ production at 95% CL.

PDF or GIF


Signature Part

Z+X+anything

X
Observed
Expected
+\sigma
-\sigma
Lepton
2
2.4
0.4
0.4
Photon
14
15.0
1.8
1.8
Missing Energy
74
55.9
9.7
5.8
Ht
53
41.3
5
5.2

Z+X+Y+anything


X+Y
Observed
Expected
+\sigma
-\sigma
Lepton+Photon
0
0.001
0.001
0.001
Lepton+Missing Energy
0
0.8
0.1
0.1
Lepton+Ht
0
0.14
0.05
0.04
Photon+Missing Energy 0
0.19
0.21
0.10
Photon+Ht 0
0.28
0.14
0.13
Missing Energy+Ht
6
3.5
0.5
0.5



Event Displays


1. Z-> ee  + Missing Energy

run 203265 run 3792931




2. Z->ee + Lepton + Missing energy

eun 196043 event 3035679


Page was last updated August 22, 2006 by Alexander Paramonov.
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