<p>Beauty quarks are pair-produced by strong interactions in multi-TeV proton-proton (pp) collisions at the CERN Large Hadron Collider (LHC). Such interactions allow for a test of perturbative Quantum Chromodynamics (QCD) in a new energy regime. The primary beauty-antibeauty quark b<span style="text-decoration:overline"> b</span> pair production mechanisms in perturbative QCD are referred to as flavor creation, flavor excitation, and gluon splitting. These three mechanisms produce b<span style="text-decoration:overline">b</span> pairs with characteristic kinematic behavior, which contribute differently to the shape of the differential b<span style="text-decoration:overline"> b</span> production cross section with respect to the difference in the azimuthal angle Δ&phis; and the combined separation variable Δ<i> R</i> = [special characters omitted] between the beauty and antibeauty quarks (b and <span style="text-decoration:overline">b</span>, respectively); with Δη being the change in the pseudorapidity η = — ln (<i>tan</i> (&thetas;/2)), &thetas; being the polar angle. These Δ&phis; and Δ<sup>R</sup> variables are collectively referred to as angular correlation variables and hence forth referred to as Δ<i> A</i>. By measuring the shape and absolute normalization of the differential production cross section distributions with respect to Δ<i>A</i> a test of the predictions of perturbative QCD can be performed. </p><p> This dissertation describes a measurement of the differential production cross sections with respect to the Δ<i>A</i> between two hadronic jets arising from the hadronization and decay of b or <span style="text-decoration:overline">b</span> (referred to as <i>b</i> hence forth) produced in pp collisions at the LHC observed with the Compact Muon Solenoid (CMS) detector. Hadronic jets are identified as originating from b quarks, i.e. b-tagged, based on the presence of high impact parameter tracks with respect to the primary pp interaction point in events in which a muon is also produced. The study presented in this dissertation corresponds to an integrated luminosity of 3 pb<sup> -1</sup> collected in 2010 by the CMS experiment at a center-of-mass energy of 7 TeV. </p><p> The visible kinematic phase-space of the differential production cross sections probed in this study is given by the requirement of two b-tagged hadronic jets with [special characters omitted] > 30 GeV and ∥η<sup>jet</sup>∥ < 2.4, with an angular separation of ΔR > 0.6 between them, one of these jets has a muon within its constituents with [special characters omitted] > 8 GeV and ∥η<sup>μ</sup>∥ < 2.1. The results obtained in data are compared with predictions based on perturbative QCD calculations given by CASCADE, MADGRAPH/MADEVENT, and PYTHIA Monte Carlo event generators. The predictions of perturbative QCD are found to be in agreement the measured differential cross sections within uncertainties. </p>
| Identifer | oai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:3572589 |
| Date | 26 September 2013 |
| Creators | Dorney, Brian Lee |
| Publisher | Florida Institute of Technology |
| Source Sets | ProQuest.com |
| Language | English |
| Detected Language | English |
| Type | thesis |
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