Investigations on the decay length method for the measurement of the top quark mass at the Atlas experiment [Elektronische Ressource] / vorgelegt von Jörg Walbersloh

Investigationson the decay length methodfor the measurementof the top quark massat the atlas experimentDissertationzur Erlangung des akademischen Gradeseines Doktors der Naturwissenschaften(Dr. rer. nat.)der Fakulatt Physikder Technischen Universit at Dortmundvorgelegt vonDipl. Phys. J org WalberslohLehrstuhl fur Experimentelle Physik IVFakult at PhysikTU Dortmundeingereicht am 21. August 2009Erstgutachter:Priv. Doz. Dr. Reiner Klingenberg, Technische Universit at DortmundZweitgutachter:Prof. Dr. Bernhard Spaan, Technische Universit at DortmundDatum der mundli chen Prufung:25. September 2009iAbstractThe precision of the determination of the top quark mass at particle colliderexperiments with methods which rely on jet energy measurements is limited due tothe jet energy scale. This thesis presents a method that relies almost exclusively ontracking and thus has complementary uncertainties with respect to other methods.This so-called decay length method correlates the mean transverse decay length ofB-Hadrons originating from top quark decays to the mass of the initial top quark.The thesis discusses the application the method for the semileptonic decay channelof tt-Events at the ATLAS detector and presents an estimate for uncertaintiesbased on MonteCarlo simulations.Contents1 Introduction 12 The ATLAS experiment 32.1 CERN and the LHC . . . . . . . . . . . . . . . . . . . . . . . . . . 32.2 The ATLAS Detector . . . . . . . . . . . . . . .