Measurement of the top quark mass in final states with two leptons

TL;DR

This paper measures the top quark mass using dilepton final states in proton-antiproton collisions, employing two different reconstruction methods and combining results for improved accuracy.

Contribution

It introduces two novel methods for reconstructing the top quark mass in dilepton events and combines their results for a more precise measurement.

Findings

Measured top quark mass as 174.7 GeV with combined uncertainties.

Analyzed 83 candidate events from the D0 dataset.

Compared two reconstruction techniques for robustness.

Abstract

We present measurements of the top quark mass in ttbar candidate events with two final state leptons using 1 inverse fb of data collected by the D0 experiment. Our data sample is selected by requiring two fully identified leptons or by relaxing one lepton requirement to an isolated track if at least one jet is tagged as a b jet. The top quark mass is extracted after reconstructing the event kinematics under the ttbar hypothesis using two methods. In the first method, we integrate over expected neutrino rapidity distributions, and in the second we calculate a weight for the possible top quark masses based on the observed particle momenta and the known parton distribution functions. We analyze 83 candidate events in data and obtain m_t = 176.2 +/- 4.8 (stat) +/- 2.1 (sys) GeV and m_t = 173.2 +/- 4.9 (stat) +/- 2.0 (sys) GeV for the two methods, respectively. Accounting for correlations between the two methods, we combine the measurements to obtain m_t = 174.7 +/- 4.4 (stat) +/- 2.0 (sys) GeV.