Measurement of the Mass Difference Between Top and Anti-top Quarks at CDF

TL;DR

This paper measures the mass difference between top and anti-top quarks using Tevatron data, finding results consistent with the standard model's prediction of no difference.

Contribution

First measurement of the top-antitop mass difference using the full Tevatron dataset with a novel event-by-event estimation method.

Findings

Mass difference ΔM_top = -1.95 ± 1.11 (stat) ± 0.59 (syst) GeV/c²

Results consistent with no mass difference as predicted by the standard model

Utilized full 8.7 fb⁻¹ dataset from CDF II detector

Abstract

We present a measurement of the mass difference between top ($t$) and anti-top ($\bar{t}$) quarks using $t\bar{t}$ candidate events reconstructed in the final state with one lepton and multiple jets. We use the full data set of Tevatron $\sqrt{s} = 1.96$ TeV proton-antiproton collisions recorded by the CDF II detector, corresponding to an integrated luminosity of 8.7 fb$^{-1}$. We estimate event-by-event the mass difference to construct templates for top-quark signal events and background events. The resulting mass difference distribution of data compared to signal and background templates using a likelihood fit yields $\Delta M_{top} = {M}_{t} - {M}_{\bar{t}} = -1.95 $pm$ 1.11 (stat) $pm$ 0.59 (syst)$ and is in agreement with the standard model prediction of no mass difference.