Measurement of the Top Quark Mass in Dilepton Final States with the Neutrino Weighting Method

Abstract

The top quark is the heaviest fundamental particle observed to date. The mass of the top quark is a free parameter in the Standard Model (SM). A precise measurement of its mass is particularly important as it sets an indirect constraint on the mass of the Higgs boson. It is also a useful constraint on contributions from physics beyond the SM and may play a fundamental role in the electroweak symmetry breaking mechanism. I present a measurement of the top quark mass in the dilepton channel using the Neutrino Weighting Method. The data sample corresponds to an integrated luminosity of 4.3 fb-1 of p$\bar{p}$ collisions at Tevatron with √s = 1.96 TeV, collected with the DØ detector. Kinematically under-constrained dilepton events are analyzed by integrating over neutrino rapidity. Weight distributions of t$\bar{t}$ signal and background are produced as a function of the top quark mass for different top quark mass hypotheses. The measurement is performed by constructing templates from the moments of the weight distributions and input top quark mass, followed by a subsequent likelihood t to data. The dominant systematic uncertainties from jet energy calibration is reduced by using a correction from `+jets channel. To replicate the quark avor dependence of the jet response in data, jets in the simulated events are additionally corrected. The result is combined with our preceding measurement on 1 fb-1 and yields mt = 174.0± 2.4 (stat.) ±1.4 (syst.) GeV.

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