Measurement of the mass difference between top and antitop quarks

TL;DR

This paper reports a precise measurement of the mass difference between top and antitop quarks using CMS data, confirming CPT invariance with improved accuracy.

Contribution

First measurement of top-antitop mass difference with enhanced precision using CMS data at the LHC.

Findings

Mass difference Delta m(t) = -0.44 +/- 0.46 (stat) +/- 0.27 (syst) GeV

Result consistent with zero, supporting CPT invariance

Improved measurement precision over previous studies

Abstract

A measurement of the mass difference between the top and the antitop quark (Delta m(t) = m(t) - m(anti-t)) is performed using events with a muon or an electron and at least four jets in the final state. The analysis is based on data collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 4.96 +/- 0.11 inverse femtobarns, and yields the value of Delta m(t) = -0.44 +/- 0.46 (stat) +/- 0.27 (syst) GeV. This result is consistent with equality of particle and antiparticle masses required by CPT invariance, and provides a significantly improved precision relative to existing measurements.