Jet Energy Scale Corrections and their Impact on Measurements of the Top-Quark Mass at CMS

The final state of many physics processes at the Large Hadron Collider(LHC) is dominated by jets, the experimental signature of quarks andgluons. The precise measurement of jets is a prerequisite to understandthese processes. In this thesis, the determination of jet-energy correctionsat CMS using dijet events is described, and the investigation of acorrection specifically tailored to improve the reconstruction of b-jets intop-quark mass measurements is presented.Dijet events are used to determine the response relative to the centraldetector region in data and simulation as a function of the pseudorapidity η . Two complementary response estimators are introduced anddetailed supplementary studies, e.g. of the time stability of the response,are performed. For the 2011 data-taking period, the MC/Data differences are found to be below 5% in the tracker-covered detector regionwith systematic uncertainties of less than 1%.Furthermore, a study of b-jet properties in 2012 data is presented.The correlation of various such observables with the response is exploitedto improve the jet-energy measurement of b-jets. A resolution improvement of about 10% can be achieved, and the evaluation of b-jet specificjet-energy scale uncertainties (b-JES) indicates improvements of about30%. This additional correction is applied to an existing measurementof the top-quark mass in the muon+jets channel. It leads to a statisticalsensitivity improvement of about 10% and a reduction of systematicuncertainties related to the b-JES from 0.6 GeV to 0.3 GeV.