Searches for supersymmetry and Higgs particles with D-Zero Page: 4 of 6
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Left Up Squark Mass Contours
Figure 1: The 95% CL limit in the mr - m, pz plane su-
perimposed on contours of constant gluino mass for A =0,
tan(3)=2 and negative A
Monte Carlo at various points in the 2-dimensional
m0 - m1/2 plane using (ISAJET 7.13)2. The three
other SUGRA parameters A0, tan(Q), sign( )
were fixed at 0, 2 and negative respectively and the
top mass was assumed to be 180 GeV. All sparticle
( gluino, squark, chargino and neutralino) produc-
tion was included in our simulated samples. The
response of the DO detector was determined us-
ing a detailed detector and trigger simulation. We
then estimated the signal efficiency at each point.
Using the signal efficiencies, background expecta-
tions and the two observed events, we have de-
termined the 95% CL upper limit on the SUSY
cross section, as a function of mn and mi1/2 us-
ing a Bayesian calculation. From these cross sec-
tion limits and the leading order estimated cross
sections, we determine the 95% CL exclusion con-
tours shown in figures 1 and 2. The excluded re-
gion is the area below the solid line. Figure 1
shows the exclusion contour superimposed on a
plot of gluino mass contours; Figure 2 shows the
same exclusion contour superimposed on the mass
contour for the left up squark. The "dip" in the
exclusion contour around m = 70 GeV is due to
the fact that inthis region is lighter than Z2
and the decay Z2 - vu replaces Z2 - eeZ1 as
the dominant decay mode.
Figure 2: The 95% CL limit in the m0 - m1/2 plane super-
imposed on contours of constant up squark mass for A0 =0.
tan(3)=2 and negative p
3 Search for charginos and neutralinos in
the trilepton channel
An established technique of searching for SUSY
at Tevatron collider is to look for trileptonic final
states from decays of the lightest chargino, W1,
and second lightest neutralino, Z2, produced in
For this analysis, we have looked for the following
four trileptonic final states: eee, eep, e , .
Various combinations of single lepton ( e or ) and
dilepton triggers were used for selecting these fi-
nal states. These triggers included: a single muon
with p! > 15 GeV/c; two muons with p4 > 3
GeV/c; one muon with p > 8 GeV/c plus one
electromagnetic cluster with ET > 7 GeV; one
electromagnetic cluster with ET > 20 GeV and
missing transverse energy, $4, > 15 GeV; and two
electromagnetic clusters with ET' > 12 GeV, E42
> 7 GeV, and $4> 7 GeV.
In addition, to reduce trigger bias, during offline
analysis the first or first two leading leptons ( de-
pending on trigger) are required to have their pr at
least 2 GeV above trigger threshold. For the chan-
nels involving muons, we rejected back to back
muons within 0.1 rad to reduce cosmic ray back-
ground and also rejected events where the $ is
either back to back to the leading muon or par-
allel to any muon within 0.1 rad. The last one is
to reduce the effect of mismeasured muon momen-
tum. We further required that any lepton in the
Gluino Mass Contours
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Mondai, N. K. Searches for supersymmetry and Higgs particles with D-Zero, article, November 1, 1996; Batavia, Illinois. (digital.library.unt.edu/ark:/67531/metadc683494/m1/4/: accessed May 25, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.