Direct Measurement of the Top Quark Mass

TL;DR

This paper reports a direct measurement of the top quark mass using proton-antiproton collision data from the Fermilab Tevatron, employing a likelihood fit method to analyze decay events.

Contribution

It introduces a novel measurement technique combining a two-constraint fit with likelihood analysis to determine the top quark mass from collision data.

Findings

Measured top quark mass: 173.3 GeV/c^2

Statistical uncertainty: 5.6 GeV/c^2

Systematic uncertainty: 6.2 GeV/c^2

Abstract

We measure the top quark mass m_t using t tbar pairs produced in the D0 detector by root(s) = 1.8 TeV p pbar collisions in a 125 pb^-1 exposure at the Fermilab Tevatron. We make a two constraint fit to m_t in t tbar --> b W^+ bbar W^- final states with one W decaying to q qbar and the other to e nu or mu nu. Events are binned in fit mass versus a measure of probability for events to be signal rather than background. Likelihood fits to the data yield m_t = 173.3 +- 5.6 (stat) +- 6.2 (syst) GeV/c^2.