A search has been performed for the trilepton decay signature from the
associated production
of the lightest chargino and the next-to-lightest neutralino in leptonic
channels with
two electrons or electron and muon within the context of minimal
Supersymmetry.
The search uses data taken with the D0 detector at the Fermilab Tevatron
ppbar
collider at a center-of-mass energy of 1.96 TeV corresponding to an
integrated luminosity of 132/pb.
No evidence for Supersymmetry has been found.
The results for both selections can be translated into 95% CL
upper limits on the cross section for associated production of charginos
and neutralinos with
decays into final states with 3 leptons.
Since both analyses cover a couple of decay channels each, the results
are
given as limits on the cross section of the process chargino+neutralino ->
3 leptons + X,
assuming equal branching fractions into the lepton flavours, which is
common as long as the
leptons are mass degenerate (for neglegible stau mixing).
They are valid for parameter combinations with comparable chargino and
neutralino mass
relations, which is true for a large part of the mSUGRA parameter space.
A detailed description is available as DØ note 4245 (restricted access; non-D0-speakers, please contact the D0 NP Convenors).
Limits on the cross section of associated neutralino-chargino
production with decays into final states with 3 leptons
depending on the chargino mass. Plotted are: the D0
RunI limit (triangles), the limit from the e+e+l analysis
(bullets) and the combined limit from the e+mu and the
e+e+l analysis (squares). LEP is excluding chargino
masses nearly up to the production limit of 103 GeV.
Distribution of the invariant diEM mass in data (points
with error
bars) and background simulation (histograms,
complemented with the QCD expectation) for events with
two tight electron candidates, one electron candidate
with pt>15 GeV.
