Korrekturen der schwachen Wechselwirkung zur hadronischen Topquark-Paarproduktion
This thesis presents the calculation of the Standard Model weak-interaction corrections of order alpha_s^2 alpha to hadronic top-quark pair production. The one-loop weak corrections to top antitop production due to gluon fusion and uark antiquark annihilation are computed. Also the order alpha_s^2 alpha corrections to top antitop production due to quark gluon and antiquark gluon scattering in the Standard Model are calculated. In this complete weak-corrections of order alpha_s^2 alpha to g g, q qbar, g q, and g qbar induced hadronic t tbar production the top and antitop polarizations and spin-correlations are fully taken into account. For the Tevatron and the LHC the weak contributions to the cross section, to the transverse top-momentum (pT) distributions, and to the top antitop invariant mass (Mtt) distributions are analyzed. At the LHC the corrections to the distributions can be of the order of -10 percent compared with the leading-order results, for pT>1500 GeV and Mtt>3000 GeV, respectively. At the Tevatron the corrections are -4 percent for pT>600 GeV and Mtt>1000 GeV. This thesis also considers parity-even top antitop spin correlations of the form d sigma(++)+d sigma(--)-d sigma(+-)-d sigma(-+), where the first and second argument denotes the top and antitop spin projection onto a given reference axis. This spin asymmetries are computed as a function of Mtt. At the LHC the weak corrections are of order of -10 percent for Mtt>1000 GeV for all analyzed reference axes. At the Tevatron the corrections are in the range of 5 percent at threshold and -5 percent for Mtt>1000 GeV. Apart from parity-even spin asymmetries also the Standard Model predictions for parity violating effects in topquark pair production are calculated. This thesis analyzes parity-violating double and single spin asymmetries, and shows how they are related if CP invariance holds. For top and antitop quarks which decay semileptonically, a resulting charged-lepton forward-backward asymmetry APV with respect to the top (antitop) direction is computed. At the LHC APV is of the order of one percent if suitable invariant-mass cuts are applied.
info:eu-repo/classification/ddc/530, Schwache Wechselwirkung, Elementarteilchenphysik, t-Quark, Paarerzeugung, Quantenchromodynamik, Physik, pairproduction, weak interaction, top quark, qcd
Networked Digital Library of Theses and Dissertations
Publikationsserver der RWTH Aachen University