Search for Microscopic Black Holes in Multi-Jet Final-States using Multiple Single-Jet Triggers with ATLAS Detector with 8 TeV Proton-Proton Collisions at the Large Hadron Collider

Higher dimensional microscopic black holes may be produced in particle accelerators at high energies which will emit a high multiplicity of Standard Model (SM) particles via thermal decay. This thesis documents a search for higher dimensional microscopic black holes in multi-jet final-states using six single-jet triggers with the ATLAS detector with 8 TeV proton-proton collisions at the Large Hadron Collider. The ATLAS 2012 data corresponds to a total integrated luminosity of 20.3 fb-1. The background topology in this search consists of all multi-jet final-states from all SM processes. Quantum Chromodynamics (QCD) processes contribute maximally to the SM multi-jet final-states and dominate this background topology. The invariant mass (M) and scalar sum of transverse momenta of all jets (HT) in events are used as analysis variables. The M and HT distributions for ATLAS data are consistent with QCD predictions of two well known hadronization models (PYTHIA8 and HERWIG++) for each single-jet trigger. Counting experiments are performed to set model-independent upper limits (at 95% confidence level) on the production cross section times acceptance times efficiency of new physics in multi-jet events. The model-independent upper limit on the production cross section times acceptance times efficiency is 0.15 fb for the threshold mass Mth > 4.5 TeV. Model-dependent production cross section limits (at 95% confidence level) are also calculated versus Mth and fundamental Planck mass MD for non-rotating and rotating black holes for two, four and six large extra dimensions.