Measurement of the Top Quark Mass and ppbar -> ttbar Cross Section in the All-Hadronic Mode with the CDFII Detector

TL;DR

This paper reports a precise measurement of the top quark mass and the top-antitop production cross section using all-hadronic decay channels with the CDFII detector, employing neural networks and likelihood fits to analyze collision data.

Contribution

It introduces a novel combined measurement technique that simultaneously determines the top quark mass, JES, and cross section in the all-hadronic mode using neural network selection and likelihood fitting.

Findings

Top quark mass measured as 174.8 GeV/c^2 with ~2.4 GeV/c^2 uncertainty.

Top-antitop cross section measured as 7.2 pb with combined uncertainties.

Method achieves improved precision in top quark property measurements.

Abstract

We present a measurement of the top quark mass and of the top-antitop pair production cross section using p-pbar data collected with the CDFII detector at the Tevatron Collider at the Fermi National Accelerator Laboratory and corresponding to an integrated luminosity of 2.9 fb-1. We select events with six or more jets satisfying a number of kinematical requirements imposed by means of a neural network algorithm. At least one of these jets must originate from a b quark, as identified by the reconstruction of a secondary vertex inside the jet. The mass measurement is based on a likelihood fit incorporating reconstructed mass distributions representative of signal and background, where the absolute jet energy scale (JES) is measured simultaneously with the top quark mass. The measurement yields a value of 174.8 +- 2.4(stat+JES) ^{+1.2}_{-1.0}(syst) GeV/c^2, where the uncertainty from the absolute jet energy scale is evaluated together with the statistical uncertainty. The procedure measures also the amount of signal from which we derive a cross section, sigma_{ttbar} = 7.2 +- 0.5(stat) +- 1.0 (syst) +- 0.4 (lum) pb, for the measured values of top quark mass and JES.