Topics in supersymmetry phenomenology at the large hadron collider

Abstract

This dissertation focuses on phenomenological studies for possible signals for supersymmetric events at the Large Hadron Collider (LHC). We have divided our endeavours into three separate projects. First, considering that the branching fraction for the decays of gluinos to third generation squarks is expected to be enhanced in classes of supersymmetric models where either third generation fermions are lighter than other squarks, or models of mixed higgsino dark matter which are constructed in agreement with the measured density of cold dark matter(CDM), the gluino production in such scenarios at the LHC should be rich in top and bottom quark jets. Requiring b-jets in addition to missing energy Emiss T should, therefore, enhance the supersymmetry signal relative to Standard Model backgrounds. We quantify the increase in the supersymmetry reach of the LHC from b-tagging in a variety of well-motivated models of supersymmetry. We also explore top-tagging at the LHC. Second, we explore the prospects for detecting the direct production of third generation squarks in models with an inverted squark mass hierarchy. This is signalled by b-jets + Emiss T events harder than in the Standard Model, but softer than those from the production of gluinos and heavier squarks. We find that these events can be readily separated from SM background (for third generation squark masses in the 200-400 GeV range), and the contamination from the much heavier gluinos and squarks although formidable can effectively be suppressed. Third, we attempt to extract model-independent information about neutralino properties from LHC data, assuming only the particle content of the MSSM and that all two-body neutralino