Top Quark Mass Measurement in the tt-bar All Hadronic Channel using a Matrix Element Technique in ppbar Collisions at sqrt s = 1.96 TeV

TL;DR

This paper measures the top quark mass in the all-hadronic decay channel using a matrix element technique on proton-antiproton collision data, achieving a precise result with detailed calibration and likelihood analysis.

Contribution

It introduces a matrix element method for top mass measurement in the all-hadronic channel, incorporating jet energy scale calibration and likelihood modeling for improved accuracy.

Findings

Measured top quark mass: 171.1 GeV/c^2

Total uncertainty: 4.3 GeV/c^2

Method enhances precision in all-hadronic channel

Abstract

We present a measurement of the top quark mass in the all-hadronic channel (\tt $\to$ \bb$q_{1}\bar{q_{2}}q_{3}\bar{q_{4}}$) using 943 pb$^{-1}$ of \ppbar collisions at $\sqrt {s} = 1.96$ TeV collected at the CDF II detector at Fermilab (CDF). We apply the standard model production and decay matrix-element (ME) to $\ttbar$ candidate events. We calculate per-event probability densities according to the ME calculation and construct template models of signal and background. The scale of the jet energy is calibrated using additional templates formed with the invariant mass of pairs of jets. These templates form an overall likelihood function that depends on the top quark mass and on the jet energy scale (JES). We estimate both by maximizing this function. Given 72 observed events, we measure a top quark mass of 171.1 $\pm$ 3.7 (stat.+JES) $\pm$ 2.1 (syst.) GeV/$c^{2}$. The combined uncertainty on the top quark mass is 4.3 GeV/$c^{2}$.