Search for CP violation using $\mathrm{t\bar{t}}$ events in the lepton+jets channel in pp collisions at $\sqrt{s}$ = 13 TeV

TL;DR

This study searches for CP violation in top quark-antiquark pair production and decay using 13 TeV proton-proton collision data, finding no evidence of CP violation and setting constraints on the top quark's chromoelectric dipole moment.

Contribution

First measurement of CP violation asymmetries in top quark pairs at 13 TeV with the CMS detector, providing new constraints on top quark CP-violating parameters.

Findings

Measured top quark chromoelectric dipole moment as 0.04 ± 0.10 (stat) ± 0.07 (syst)

No evidence of CP violation observed in the data

Results are consistent with the Standard Model expectations

Abstract

Results are presented on a search for CP violation in the production and decay of top quark-antiquark pairs in the lepton+jets channel. The search is based on data from proton-proton collisions at 13 TeV, collected with the CMS detector, corresponding to an integrated luminosity of 138 fb$^{-1}$. Possible CP violation effects are evaluated by measuring uncorrected asymmetries in observables constructed from linearly independent four-momentum vectors of the final-state particles. The dimensionless chromoelectric dipole moment of the top quark obtained from the observed asymmetries is measured to be 0.04 $\pm$ 0.10 (stat) $\pm$ 0.07 (syst), and the asymmetries exhibit no evidence for CP-violating effects, consistent with expectations from the standard model.