The first measurement of the top quark mass at CDF II in the lepton+jets and dilepton channels simultaneously

TL;DR

This paper reports the first simultaneous measurement of the top quark mass in lepton+jets and dilepton channels using CDF II data, employing a novel two-dimensional likelihood fit to improve precision.

Contribution

It introduces a combined analysis method for different decay channels of top quark pairs, enhancing measurement accuracy by fitting for the mass and jet energy scale simultaneously.

Findings

Measured top quark mass: 171.9 GeV/c^2

Achieved combined statistical and systematic uncertainty of 2.0 GeV/c^2

Demonstrated the effectiveness of simultaneous channel analysis

Abstract

We present a measurement of the mass of the top quark using data corresponding to an integrated luminosity of 1.9fb^-1 of ppbar collisions collected at sqrt{s}=1.96 TeV with the CDF II detector at Fermilab's Tevatron. This is the first measurement of the top quark mass using top-antitop pair candidate events in the lepton + jets and dilepton decay channels simultaneously. We reconstruct two observables in each channel and use a non-parametric kernel density estimation technique to derive two-dimensional probability density functions from simulated signal and background samples. The observables are the top quark mass and the invariant mass of two jets from the W decay in the lepton + jets channel, and the top quark mass and the scalar sum of transverse energy of the event in the dilepton channel. We perform a simultaneous fit for the top quark mass and the jet energy scale, which is constrained in situ by the hadronic W boson mass. Using 332 lepton + jets candidate events and 144 dilepton candidate events, we measure the top quark mass to be mtop=171.9 +/- 1.7 (stat. + JES) +/- 1.1 (syst.) GeV/c^2 = 171.9 +/- 2.0 GeV/c^2.