Scholars@Duke publication: Top quark mass measurement using the template method in the lepton + jets channel at CDF II

Top quark mass measurement using the template method in the lepton + jets channel at CDF II

Publication , Journal Article

Abulencia, ; A, ; others,

Published in: Phys. Rev.

2006

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.