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Discovery Potential for Quantum Black Holes in the Di-Top Quark Final State at the Large Hadron Collider

  • Author / Creator
    Sina Safarabadi Farahani
  • Models postulating large extra dimensions or a warped extra dimension allow the reduction of the Planck scale to the order of a few TeV. These energies may be accessible by the Large Hadron Collider particle accelerator. Quantum black holes are predicted to be produced from particle collisions with energies near the Planck scale. Quantum black holes decay into few-particle final states. This thesis looks into the simulation of such objects and their decay to the t t final state in the fully-hadronic and semi-hadronic topologies with a centre-of-mass energy of 13 TeV. Quantum chromodynamic processes dominate the background in both topologies. The ADD model (Arkani-Hamed, Dimopoulos, and Dvali) postulating n = {2, 4, 6} large extra dimensions and the RS1 (Randall-Sundrum type I) model are studied. The discovery of quantum black holes with production mass threshold below {9.1, 8.9, 8.5} TeV and {10.0, 9.8, 9.4} TeV using 150 fb^{-1} and 3000 fb^{-1} , respectively, for the ADD model with n = {2, 4, 6} could be possible. Quantum black holes in the RS1 model could be found with a production threshold mass below 6.2 TeV and 7.3 TeV, respectively. Also, using 37.4 fb^{-1} of ATLAS data, upper limits at the 95% confidence level on the quantum black hole production cross-section times branching ratio to the t t final state times acceptance times efficiency versus threshold production mass are calculated. The limits are found to be 5.9 fb at 4.0 TeV and 0.11 fb at 8.0 TeV. There are no data for masses above 8.3 TeV which sets the limit to 0.08 fb for higher masses. Using the above models, the result excludes the production of ADD quantum black holes with threshold mass less than {7.6, 7.2, 6.2} TeV in the t t channel. Due to the lower cross-section of quantum black holes in the RS1 model, no exclusion limit could be set for quantum black holes decaying to tt in the RS1 model.

  • Subjects / Keywords
  • Graduation date
    Fall 2019
  • Type of Item
    Thesis
  • Degree
    Master of Science
  • DOI
    https://doi.org/10.7939/r3-jax6-8337
  • License
    Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.