Single lepton charge asymmetries in $t \bar t$ and $t \bar t \gamma$ production at the LHC

TL;DR

This paper explores lepton charge asymmetries in top-antitop and top-antitop-photon production at the LHC, showing their potential to detect new physics scenarios with high sensitivity, especially with future high luminosity upgrades.

Contribution

The study introduces new leptonic charge asymmetries in $t ar t ext{ and } t ar t ext{ } ext{photon}$ production and analyzes their sensitivity to new physics at the LHC.

Findings

Asymmetries in $t ar t$ can be competitive with existing measurements.

High luminosity LHC can enhance sensitivity to new physics.

Asymmetries can detect deviations at 3-4 sigma level.

Abstract

We discuss lepton charge asymmetries in $t \bar t$ and $t \bar t \gamma$ production at the LHC, which can be measured in the semileptonic decay channel $t \bar t \to W^+ b \, W^- \bar b \to \ell^+ \nu b \, q \bar q' \bar b$ (or the charge conjugate). Considering several variants of a new physics scenario with a light colour octet, it is seen that for $t \bar t$ these asymmetries may have a sensitivity competitive with the dilepton asymmetry already measured. For $t \bar t \gamma$ the new leptonic asymmetries, as well as the $t \bar t$ charge asymmetry, will reach their full potential with the high luminosity LHC upgrade. These asymmetries can pinpoint deviations at the $3\sigma-4\sigma$ level for new physics scenarios where the charge asymmetries already measured in $t \bar t$ production agree within $1\sigma$.