This article presents a measurement of the top quark mass using
the CDF II detector at Fermilab. Colliding beams of protons and
anti-protons at Fermilab's Tevatron (s**(1/2) = 1.96 TeV) produce top/anti-top
pairs, which decay to W+ W- bb-bar; events are selected where one W decays
to hadrons, and the other W decays to either e or mu plus a neutrino. The
data sample corresponds to an integrated luminosity of approximately 318
pb-1. A total of 165 tt-bar events are separated into four subsamples
based on jet transverse energy thresholds and the number of b jets
identified by reconstructing a displaced vertex. In each event, the
reconstructed top quark invariant mass is determined by minimizing a chi2
for the overconstrained kinematic system. At the same time, the mass of the
hadronically decaying W boson is measured in the same event sample. The
observed W boson mass provides an in situ improvement in the determination
of the hadronic jet energy scale, JES. A simultaneous likelihood fit of the
reconstructed top quark masses and the W boson invariant masses in the data
sample to distributions from simulated signal and background events gives a
top quark mass of 173.5+3.7_-3.6(stat. + JES) +/- 1.3 (other syst.)
GeV/c2, or 173.5+3.9_-3.8 GeV/c2.
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Updated: Tuesday, 2006 March 14 14:07:05 CST automatically from input from Carol Picciolo