Top quark and leptonic charge asymmetries for the Tevatron and LHC

TL;DR

This paper delivers a thorough SM evaluation of top-quark charge asymmetries at NLO QCD, augmented by mixed QCD-QED and QCD-weak corrections, for both Tevatron and LHC. It computes a suite of hadronic asymmetries (A(y), A, A^{t\bar t}) and a broad set of leptonic observables arising from tt̄ decays, with and without kinematic cuts, and contrasts the results with experimental data. The work shows that electroweak corrections can sizablely modify QCD predictions and that LHC observables, though small, are within measurable reach and provide robust tests of the SM and potential new physics. Overall, the SM baseline established here supports consistency with most LHC measurements, while clarifying the residual tensions at Tevatron high-mass bins and outlining how future measurements, including leptonic channels, can further constrain new physics scenarios.

Abstract

We compute, for $t \bar t$ production at the LHC and at the Tevatron, several charge asymmetries to NLO QCD, including also the electromagnetic and weak-interaction corrections. We calculate these asymmetries both inclusively and with additional kinematic cuts and compare our results, where possible, with recent experimental results and with SM predictions. The $t \bar t$ asymmetries induce also corresponding asymmetries for the charged leptons from semileptonic top-quark decay. Although these asymmetries are, in the SM, smaller than the corresponding ones for top quarks, they are expected to be measurable quite precisely. In fact, measurement of a lepton asymmetry in $\ell$ + jets events was reported by the D$\emptyset$ and CDF experiments. We analyze and compute to NLO in the gauge couplings leptonic charge asymmetries for dileptonic and semileptonic $\ttbar$ events, with and without acceptance cuts, at the Tevatron and the LHC.