Search for Supersymmetry in Trilepton Final States with the DØ Experiment

by Jason Dhia Mansour
Doctoral thesis
Date of Examination:2014-11-19
Date of issue:2015-10-27
Advisor:Dr. Carsten Hensel
Referee:Prof. Dr. Arnulf Quadt
Referee:PD Dr. Jörn Große-Knetter
Persistent Address: http://dx.doi.org/10.53846/goediss-5332

 

 

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Abstract

English

A search for supersymmetry in the trilepton final state is performed using the full dataset of the DØ experiment. The analyzed data amounts to an integrated luminosity of ∫ℒ = 9.7 fb⁻¹ of pp̅ collisions, produced at √s = 1.96 TeV at the Fermilab Tevatron collider. The studied process is the coproduction of charginos and neutralinos, decaying into a final state of three leptons and missing transverse energy. To increase efficiency, only two identified leptons (e, µ) and one additional isolated track are required per event. The QCD multijet background is estimated from data, while other backgrounds are modeled via Monte Carlo. After a series of background-reduction cuts, a multivariate analysis is performed using boosted decision trees (BDT). In the distribution of the BDT output, no excess of data over background is seen. Limits on the cross section are set for the mSUGRA (CMSSM) model, as well as for a scenario with non-universal gaugino masses.
Keywords: Supersymmetry; Hadron collider physics; Tevatron; DZero; Particle Physics; Trileptons
 
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