Heavy-flavour tagging and the supersymmetry reach of the CERN Large Hadron Collider

Abstract

The branching fraction for the decays of gluinos to third generation quarks is expected to be enhanced in classes of supersymmetric models where either third generation squarks are lighter than other squarks, or in mixed-higgsino dark matter models constructed to be in concordance with the measured density of cold dark matter. In such scenarios, gluino production events at the CERN Large Hadron Collider should be rich in top and bottom quark jets. Requiring b-jets in addition to missing transverse energy should, therefore, enhance the supersymmetry signal relative to Standard Model backgrounds from V + jet, VV and QCD backgrounds (V=W, Z). 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. We find that while the efficiency for this turns out to be too low to give an increase in reach beyond that obtained via b-tagging, top-tagging can indeed provide a confirmatory signal if gluinos are not too heavy. Finally, 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 + missing transverse energy events harder than in the Standard Model, but softer than those from the production of gluinos and heavier squarks. We find that while these events can be readily separated from SM background (for third generation squark masses ~300-500 GeV), the contamination from the much heavier gluinos and squarks remains formidable if these are also accessible.

Minor changes in the text, with addition and update of the references. To be published in the European Physical Journal C

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Cited by in corpus (6)

• Constraining the MSSM with universal gaugino masses and implication for searches at the LHC
• Exploring compressed supersymmetry with same-sign top quarks at the Large Hadron Collider
• The Reach of the High-Energy LHC for Gluinos and Top Squarks in SUSY Models with Light Higgsinos
• Signals of supersymmetry with inaccessible first two families at the Large Hadron Collider
• Post LHC7 SUSY benchmark points for ILC physics
• Prospects for Hypercharged Anomaly Mediated SUSY Breaking at the LHC