Measurement of the mass difference between top quark and antiquark in pp collisions at sqrt(s) = 8 TeV

TL;DR

This paper measures the mass difference between top quark and antiquark in proton-proton collisions at 8 TeV, testing CPT invariance and finding results consistent with the standard model with high precision.

Contribution

The study provides the most precise measurement to date of the top-antitop mass difference, using CMS data at 8 TeV to test CPT invariance.

Findings

Mass difference Delta m[t] = -0.15 +/- 0.21 GeV

Results consistent with zero, supporting CPT invariance

More precise than previous measurements

Abstract

The invariance of the standard model (SM) under the CPT transformation predicts equality of particle and antiparticle masses. This prediction is tested by measuring the mass difference between the top quark and antiquark (Delta m[t] = m[t] - m[t-bar]) that are produced in pp collisions at a center-of-mass energy of 8 TeV, using events with a muon or an electron and at least four jets in the final state. The analysis is based on data corresponding to an integrated luminosity of 19.6 inverse femtobarns collected by the CMS experiment at the LHC, and yields a value of Delta m[t] = -0.15 +/- 0.19 (stat) +/- 0.09 (syst) GeV, which is consistent with the SM expectation. This result is significantly more precise than previously reported measurements.