Top quark and leptonic charge asymmetries for the Tevatron and LHC

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.Comment: Some references and a note added on comparisons with recent experimental results. Published in Phys. Rev. D 86, 034026 (2012

NNLO QCD predictions for fully-differential top-quark pair production at the Tevatron

“…[113]. While the setups for the calculation of the cos θ distribution (as well as the related Legendre moments, see below) in this work and in ref.…”

“…While the setups for the calculation of the cos θ distribution (as well as the related Legendre moments, see below) in this work and in ref. [113] differ in several aspects, we have cross-checked the pure NLO QCD results with ref. [113] 4 and found that they are in reasonable agreement (for the Legendre moments the agreement is only good for the first four moments due to differences in the way the moments are computed).…”

“…We do not have EW corrections computed in a form that is readily combinable with our QCD calculation. Therefore, as a rough estimate of the EW corrections, we take the difference between the known NLO+EW result [113] and our NLO calculation. We attribute the difference to pure non-QCD corrections and add them to the NNLO QCD ones:…”

Simultaneous measurement of forward-backward asymmetry and top polarization in dilepton final states fromtt¯production at the Tevatron

“…The interferences with electroweak processes increase the asymmetry. In the SM, the asymmetry is predicted to be ≈ 10% [1][2][3]. Within the SM, the longitudinal polarizations of the top quark and antiquark are due to parity violating electroweak contributions to the production process.…”

Top Physics at CMS/LHC

“…The measured values are compared to NLO predictions for the SM based on calculations by Kühn and Rodrigo (K&R) [39] and Bernreuther and Si (B&S) [37,40], as well as to the predictions of a model featuring an effective axial-vector coupling of the gluon (EAG) [41,42]. The inner bars indicate the statistical uncertainties, while the outer bars represent the statistical and systematic uncertainties added in quadrature.…”