Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √𝑠 = 13 TeV

Abstract

The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (𝑑̂ t) and chromomagnetic (𝜇̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable 𝐴(1)FB is used to approximate the asymmetry. Candidate tt⎯⎯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for tt⎯⎯ final states. The values found for the parameters are 𝐴(1)FB=0.048+0.095−0.087(stat)+0.020−0.029(syst),𝜇̂ t=−0.024+0.013−0.009(stat)+0.016−0.011(syst), and a limit is placed on the magnitude of ∣∣𝑑̂ t∣∣< 0.03 at 95% confidence level.