TY - THES
TI - Top quark pair production at the LHC
AB - One of the most interesting and manifold processes in the Standard Model of elementary particle physics is the top quark pair production. It enabled the discovery of the top quark at the Tevatron in 1995 and the determination of many of its properties. By means of a precise measurement and calculation of the cross section of top quark pair production it is possible to extract the top quark mass. Improvements in the gluon parton distribution functions (important for the Higgs boson production) or improvements in the prediction of the Higgs mass are also closely linked with the top quark pair production. Furthermore, the production process plays an important role in the discovery of new physics. On the one hand the top quark pair decays form the largest part of the background in many BSM models, on the other hand BSM physics can be detected directly in the decay process by investigating the charge symmetry or the invariant mass spectrum. At the LHC it will be possible for the first time to produce a large amount of top quarks; thereby the statistical errors of the observables will be strongly reduced. The enormous increase in the production rate has two reasons. On the one hand, the acceleration energy of the LHC (14 TeV and 7 TeV) is significantly greater than that of the Tevatron (1.96 Tev). This leads to an increase of the cross section by a factor of 100 ({proportional_to}7.3 pb at the Tevatron to {proportional_to}800 pb at 14 TeV LHC). On the other hand, the luminosity of the LHC outperforms the Tevatron by a factor of 10-100. The reduced experimental errors for the observables demand an improvement of the theoretical error. The experimental accuracy of the LHC and the great relevance of the process led to an intensive activity of different research groups in order to improve the calculation of the cross section of top quark pair production. This work presents for the first time a complete numerical result for the full NNLO correction for the top quark pair production in quark anti-quark annihilation channel, and the result of the double virtual corrections in the gluon fusion channel. The latter was calculated by the author in his doctoral thesis autonomously. Our results agree with already published partial results. Furthermore, the author was involved in the improvement of the double virtual corrections in the quark annihilation channel through implementation of newly developed methods. The complete NNLO results enable a reduction of the scale dependence of the production process from 15% to 4%. This allows an excellent comparison with the experimental results. Another essential component of this work, was the development and implementation of new methods for the computer-aided calculation of the production process.
AU - Baernreuther, Peter
KW - 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
KW - ANNIHILATION
KW - COMPUTER CALCULATIONS
KW - CORRECTIONS
KW - DIFFERENTIAL CROSS SECTIONS
KW - GLUON-GLUON INTERACTIONS
KW - INTEGRAL CROSS SECTIONS
KW - PAIR PRODUCTION
KW - PERTURBATION THEORY
KW - PROTON-PROTON INTERACTIONS
KW - QUANTUM CHROMODYNAMICS
KW - QUARK-ANTIQUARK INTERACTIONS
KW - SCALING LAWS
KW - T ANTIQUARKS
KW - TEV RANGE
KW - VIRTUAL PARTICLES
DO -
UR - https://www.osti.gov/etdeweb/servlets/purl/22188281
PB -
CY - Germany
PY - 2012
DA - 2012-06-28
LA - English
J2 -
C1 - RWTH Aachen Univ. (Germany). Fakultaet fuer Mathematik, Informatik und Naturwissenschaften
C2 -
ER -