Search for
Supersymmetric Particles
Using the DELPHI Detector

Per Andersson

December 1997

Akademisk avhandling
för avläggande av
filosofie licentiatexamen
vid Stockholms Universitet.

Abstract

In this thesis a report is given on the search for supersymmetric particles that has been conducted with data collected at the DELPHI detector at the Large Electron and Positron collider at CERN. The data was collected in 1995 and 1996, with centre-of-mass energies 130-136, 161 and 172 GeV. No signal was found. This has been interpreted as model independent limits on the production cross-sections of different topologies, as well as limits on the parameter space within the MSSM with gaugino and sfermion mass unification at the GUT scale. Assuming heavy sfermions, the mass of a neutralino LSP is constrained to be greater than 24.9 GeV for $\tan\beta\ge$1.0 . 1. 1.0 0. 0.