Measurement of the $\mathrm{t\bar{t}}$ charge asymmetry in events with highly Lorentz-boosted top quarks in pp collisions at $\sqrt{s}$ = 13 TeV

TL;DR

This paper measures the charge asymmetry in highly Lorentz-boosted top quark pair events at 13 TeV, using CMS data, and finds results consistent with the Standard Model predictions, especially at high invariant masses.

Contribution

It introduces a novel analysis optimized for boosted top quarks with nonisolated leptons and overlapping jets, providing the first measurement of charge asymmetry in this regime at 13 TeV.

Findings

Measured charge asymmetry of (0.42 $_{-0.69}^{+0.64}$)%

Results agree with Standard Model predictions

Analysis performed for different invariant mass ranges

Abstract

The measurement of the charge asymmetry in top quark pair events with highly Lorentz-boosted top quarks decaying to a single lepton and jets is presented. The analysis is performed using proton-proton collisions at $\sqrt{s}$ = 13 TeV with the CMS detector at the LHC and corresponding to an integrated luminosity of 138 fb$^{-1}$. The selection is optimized for top quarks produced with large Lorentz boosts, resulting in nonisolated leptons and overlapping jets. The top quark charge asymmetry is measured for events with a $\mathrm{t\bar{t}}$ invariant mass larger than 750 GeV and corrected for detector and acceptance effects using a binned maximum likelihood fit. The measured top quark charge asymmetry of (0.42 $_{-0.69}^{+0.64}$)% is in good agreement with the standard model prediction at next-to-next-to-leading order in quantum chromodynamic perturbation theory with next-to-leading-order electroweak corrections. The result is also presented for two invariant mass ranges, 750-900 and $\gt$ 900 GeV.