Measurement of the top-quark mass in the lepton+jets channel using a matrix element technique with the CDF II detector

TL;DR

This paper measures the top-quark mass using a matrix element technique on Tevatron data, achieving a precise result by simultaneously calibrating jet energy scale with in situ methods.

Contribution

It introduces a novel unbinned likelihood approach that combines signal and background matrix elements with in situ jet energy calibration to improve top-quark mass measurement accuracy.

Findings

Top-quark mass measured as 172.4 GeV/c^2

Achieved combined statistical and JES uncertainty of 1.4 GeV/c^2

Total systematic uncertainty of 1.3 GeV/c^2

Abstract

A measurement of the top-quark mass is presented using Tevatron data from proton-antiproton collisions at center-of-mass energy $\sqrt{s}=1.96$ TeV collected with the CDF II detector. Events are selected from a sample of candidates for production of $t\bar t$ pairs that decay into the lepton+jets channel. The top-quark mass is measured with an unbinned maximum likelihood method where the event probability density functions are calculated using signal and background matrix elements, as well as a set of parameterized jet-to-parton transfer functions. The likelihood function is maximized with respect to the top-quark mass, the signal fraction in the sample, and a correction to the jet energy scale (JES) calibration of the calorimeter jets. The simultaneous measurement of the JES correction ($\JES$) amounts to an additional \textit{in situ} jet energy calibration based on the known mass of the hadronically decaying $W$ boson. Using the data sample of 578 lepton+jets candidate events, corresponding to 3.2 $fb^{-1}$ of integrated luminosity, the top-quark mass is measured to be $m_t = \rm 172.4 \pm 1.4\:(stat+\JES) \pm 1.3\:(syst) GeV/{\it c}^2$.