Measurement of the top quark mass at CDF using the "neutrino $\phi$ weighting" template method on a lepton plus isolated track sample

TL;DR

This paper measures the top quark mass using dilepton events from proton-antiproton collisions at Fermilab, employing a neutrino azimuthal weighting method to reconstruct the mass with a likelihood fit.

Contribution

It introduces a novel neutrino phi weighting template method for top quark mass measurement in dilepton events, improving mass reconstruction accuracy.

Findings

Measured top quark mass: 165.5 GeV/c^2

Statistical uncertainty: ±3.4 GeV/c^2

Systematic uncertainty: ±3.1 GeV/c^2

Abstract

We present a measurement of the top quark mass with t-tbar dilepton events produced in p-pbar collisions at the Fermilab Tevatron $\sqrt{s}$=1.96 TeV and collected by the CDF II detector. A sample of 328 events with a charged electron or muon and an isolated track, corresponding to an integrated luminosity of 2.9 fb$^{-1}$, are selected as t-tbar candidates. To account for the unconstrained event kinematics, we scan over the phase space of the azimuthal angles ($\phi_{\nu_1},\phi_{\nu_2}$) of neutrinos and reconstruct the top quark mass for each $\phi_{\nu_1},\phi_{\nu_2}$ pair by minimizing a $\chi^2$ function in the t-tbar dilepton hypothesis. We assign $\chi^2$-dependent weights to the solutions in order to build a preferred mass for each event. Preferred mass distributions (templates) are built from simulated t-tbar and background events, and parameterized in order to provide continuous probability density functions. A likelihood fit to the mass distribution in data as a weighted sum of signal and background probability density functions gives a top quark mass of $165.5^{+{3.4}}_{-{3.3}}$(stat.)$\pm 3.1$(syst.) GeV/$c^2$.