Top Quark Mass Measurement in the Lepton plus Jets Channel Using a Modified Matrix Element Method

TL;DR

This paper presents a precise measurement of the top quark mass using a modified matrix element method on proton-antiproton collision data, incorporating neural network discrimination and in situ jet energy calibration.

Contribution

It introduces a modified matrix element approach with effective propagators and a neural network to improve top quark mass measurement accuracy.

Findings

Measured top quark mass: 172.7 GeV/c^2

Total uncertainty: approximately 2.2 GeV/c^2

Method reduces background and systematic uncertainties

Abstract

We report a measurement of the top quark mass, m_t, obtained from ppbar collisions at sqrt(s) = 1.96 TeV at the Fermilab Tevatron using the CDF II detector. We analyze a sample corresponding to an integrated luminosity of 1.9 fb^-1. We select events with an electron or muon, large missing transverse energy, and exactly four high-energy jets in the central region of the detector, at least one of which is tagged as coming from a b quark. We calculate a signal likelihood using a matrix element integration method, with effective propagators to take into account assumptions on event kinematics. Our event likelihood is a function of m_t and a parameter JES that determines /in situ/ the calibration of the jet energies. We use a neural network discriminant to distinguish signal from background events. We also apply a cut on the peak value of each event likelihood curve to reduce the contribution of background and badly reconstructed events. Using the 318 events that pass all selection criteria, we find m_t = 172.7 +/- 1.8 (stat. + JES) +/- 1.2 (syst.) GeV/c^2.