Measurement of the top quark mass and top-antitop production cross section from dilepton events at the Collider Detector at Fermilab

Abstract

We present an analysis of dilepton events originating from top-antitop production in proton-antiproton collisions at sqrt{s}=1.8 TeV at the Fermilab Tevatron Collider. The sample corresponds to an integrated luminosity of 109+-7 pb^{-1}. We observe 9 candidate events, with an estimated background of 2.4+-0.5 events. We determine the mass of the top quark to be M_top = 161+-17(stat.)+-10(syst.) GeV/c^2. In addition we measure a top-antitop production cross section of 8.2+4.4-3.4 pb (where M_top = 175 GeV/c^2 has been assumed for the acceptance estimate).

Figures (3)

• Figure 1: Azimuthal angle between $\,/\!\!\!\!E_{T}$ and the nearest lepton or jet, versus $|\,/\!\!\!\!E_{T}|$ for events with two leptons and two jets. The dashed line represents the $\,/\!\!\!\!E_{T}$ cut. The small dots are for $t\bar{t}$ Monte Carlo for $M_{top}$ = 175 GeV/$c^2$ and correspond to an integrated luminosity of about $24 ~{\rm fb}^{-1}$. The larger symbols represent the data.
• Figure 2: Comparison of $H_{T}$ for the candidate events (histogram) and the expectation from $t\bar{t}$ production ($M_{top}$ = 175 GeV/$c^2$) plus background (lighter shaded area). The background distribution alone is represented by the darker shaded area.
• Figure 3: (a) Jet energy distribution of the two highest ${E}_{T}$ jets for the dilepton events (histogram). Superimposed is the same distribution for $t\bar{t}$ Monte Carlo ($M_{top}$=160 GeV/$c^{2}$) plus background (lighter shade), and the background alone (darker shade). The $t\bar{t}$ plus background distribution is normalized to the data. In the inset we show the $-\ln({\cal{L}}_m)$ fit as a function of $M_{top}$ (the minimum has been offset to be at zero). (b) Distribution of ${M_{\ell b}^2}_{min}$ (histogram). Superimposed is the expectation from $t\bar{t}$ Monte Carlo ($M_{top}$=160 GeV/$c^{2}$) plus background (lighter shade), and background alone (darker shade).