Search for Charged-Lepton Flavour Violation in Top-Quark Decays in the μτ Channel using the ATLAS Detector at the LHC
Published in CERN Document Server, 2019
In brief: Master thesis carried out in the University of Bonn, Germany (Supervisor: Dr. Markus Cristinziani)
Abstract: This analysis presents a first direct search for charged-lepton flavour violation in top-quark decays to the μτ final state using data collected from proton-proton collisions at the LHC, during the years 2015 √s = 13 TeV, corresponding to an integrated luminosity of and 2016, at a centre-of-mass energy of 36.1 fb−1, as detected by the ATLAS experiment. The search is performed by studying top-quark pair events where one quark undergoes a flavour-violating decay t(t) → l±l′∓q(q), where q ∈ {u, c} and l ∈ {μ, τ} while the other top decays according to the SM into a b-quark and a leptonically-decaying W-boson. Data is found to be compatible with the absence of a signal and a fit to the background is performed using the profile likelihood technique. The observed (expected) upper limit on the branching ratio of tLFV → μτq is set to 0.96(1.00) × 10−4 at the 95% confidence level using the modified frequentist approach.
Recommended citation: ‘RUINA, Arshia. Search for Charged-Lepton Flavour Violation in Top-Quark Decays in the μτ Channel using the ATLAS Detector at the LHC. Master thesis, 2019.’