Search for the Associated Production of Chargino and Neutralino in Trilepton Final States

The D0 Collaboration

Contact Persons: Ulla Blumenschein, Volker Buescher

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 Dě 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.

Volker Buescher
Last modified: Fri Sep 5 04:26:38 CDT 2003