Top Quark Mass Measurement from Dilepton Events at CDF II

TL;DR

This first application of a matrix-element technique to tt --> bl+ nu(l)bl'- nu'+ nu'(l') decays gives the most precise single measurement of M(t) in dilepton events.

Abstract

We report a measurement of the top quark mass using events collected by the CDF II Detector from ppbar collisions at \sqrt{s} = 1.96 TeV at the Fermilab Tevatron. We calculate a likelihood function for the top mass in events that are consistent with ttbar->bbar l^- \nubar b l^+ νdecays. The likelihood is formed as the convolution of the leading-order matrix element and detector resolution functions. The joint likelihood is the product of likelihoods for each of 33 events collected in 340 pb^{-1} of integrated luminosity, yielding a top quark mass M_t = 165.2 +- 6.1 (stat.) +- 3.4(syst.) GeV/c^2. This first application of a matrix-element technique to ttbar->bbar l^- \nubar b l^+ νdecays gives the most precise single measurement of M_t in dilepton events. Combined with other CDF Run II measurements using dilepton events, we measure M_{t} = 167.9 +- 5.2 (stat.) +- 3.7 (syst.) GeV/c^2.

Figures (2)

• Figure 1: Mean measured $M_t$ in Monte Carlo experiments of signal and background events at varying top quark mass. The solid line is a linear fit to the points.
• Figure 2: Joint posterior probability density as a function of the top quark mass for the 33 candidate events in data, after all corrections. Systematic uncertainties are not shown.