Determinations of the mass of the top quark.

Abstract

The distributions of topological variables of <italic>tt&macr;</italic> events depend on the mass of the top quark. Hence, the mass of the top quark can be inferred from a comparison of the measured distributions of <italic> tt&macr;</italic> candidate events with those expected from <italic>tt&macr; </italic> and from background. Three such analyses will be presented using three groups of variables. The first analysis uses unique event-variables such as total transverse energy (<italic>H_T</italic>), transverse mass (<italic>M_T</italic>), and total mass (<italic>M</italic>) of the event. The second analysis uses <italic>E_T</italic> distributions of the leading four jets (<italic>E_Tj</italic>₁, <italic> E_Tj</italic>₂, <italic>E_Tj</italic>₃, <italic>E_Tj</italic>₄). The third analysis uses the reconstructed top-quark masses (<italic>M_jlnu</italic>, <italic> M_jjj</italic>). The top-quark masses inferred from these three analyses for the 37 lepton+jets data events are consistent with that determined previously using kinematically-constrained fits. Among the three, the third one yields the smallest uncertainties. The top-quark mass extracted from the distributions of <italic>M_jlnu</italic> and <italic>M_jjj</italic> is 184.2-6.3+7.1 (stat) +/- 4.5(syst) GeV/c<super>2</super>, with the number of background events constrained to be near 17.