Göttingen 2012 – scientific programme

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T: Fachverband Teilchenphysik

T 15: Beyond the Standard Model (Theorie) 1

T 15.8: Talk

Monday, February 27, 2012, 18:30–18:45, VG 3.102

Anomalous Top Couplings in Whizard 2 — •Fabian Bach and Thorsten Ohl — Institut für Theoretische Physik und Astrophysik, Uni Würzburg

The origin of the quark mass hierarchy within the Standard Model (SM) is still unclear. The top quark is particularly interesting because of its natural Yukawa coupling strength and corresponding large mass. The latter has made it hard to access experimentally so far. At the LHC, however, large abundances of top quarks are being produced over the next years, providing the statistics necessary to measure various properties of the top quark with high precision. Using effective field theory, it is possible to parameterize any new physics contributing to top interactions via anomalous top quark–gauge boson couplings ttγ, ttZ, tbW and ttg, while contact terms (e. g. ttgg) have to be included in general to ensure gauge invariance. The full gauge-invariant set of operators leading to anomalous trilinear top couplings has been implemented into the parton-level Monte Carlo generator WHIZARD 2 to provide a consistent tool for MC studies of the complete hard scattering amplitudes including decays of top quarks and heavy gauge bosons as well as all irreducible backgrounds. We show results in the anomalous tbW sector, focussing on the influence of off-shell interactions required by the completeness of the operator basis, and finally discuss sensitive kinematic distributions to discriminate different operator contributions.