Charge asymmetries of top quarks at hadron colliders revisited

125

We present a comprehensive study of differential distributions for Tevatron top-pair events at the level of stable top quarks. All calculations are performed in NNLO QCD with the help of a fully differential partonic Monte-Carlo and are exact at this order in perturbation theory. We present predictions for all kinematic distributions for which data exists. Particular attention is paid on the top-quark forward-backward asymmetry which we study in detail. We compare the NNLO results with existing approximate NNLO predictions as well as differential distributions computed with different parton distribution sets. Theory errors are significantly smaller than current experimental ones with overall agreement between theory and data.

Section: Nnlo Qcd + Ew(naive) = Nnlo Qcd + Nlo(qcd + Ew [113])supporting

confidence: 88%

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

Czakon

Fiedler

Heymes

et al. 2016

125

“…In ref. [53], the authors have investigated this behaviour in presence of selection cuts on the tt pair invariant mass, including also EW corrections.…”

Section: Top-quark Forward-backward Charge Asymmetrymentioning

confidence: 99%

Hadronic top-quark pair-production with one jet and parton showering

Alioli

Moch

Uwer

2012

135

137

We present a calculation of heavy-flavor production in hadronic collisions in association with one jet matched to parton shower Monte Carlo programs at next-toleading order in perturbative QCD. Top-quark decays are included and spin correlations in the decay products are taken into account. The calculation builds on existing results for the radiative corrections to heavy-quark plus one jet production and uses the POWHEG BOX for the interface to the parton shower programs PYTHIA or HERWIG. A broad phenomenological study for the Large Hadron Collider and the Tevatron is presented. In particular we study -as one important sample application -the impact of the parton shower on the top-quark charge asymmetry.

“…The latter might be underestimated due to higher-order QCD and electroweak effects [5] (see also the impact of the renormalization scale uncertainty [6]), yet the above series of observations is certainly worth exploring in the context of NP beyond the SM. There are two LHC measurements of direct relevance to the top A tt FB : the tt differential cross section as a function of M tt and the charge asymmetry (A C ) in tt production.…”

Section: Introductionmentioning

confidence: 99%

Predictions from heavy new physics interpretation of the top forward-backward asymmetry

Delaunay

Gedalia

Hochberg

et al. 2012

We derive generic predictions at hadron colliders from the large forwardbackward asymmetry observed at the Tevatron, assuming the latter arises from heavy new physics beyond the Standard Model. We use an effective field theory approach to characterize the associated unknown dynamics. By fitting the Tevatron tt data we derive constraints on the form of the new physics. Furthermore, we show that heavy new physics explaining the Tevatron data generically enhances at high invariant masses both the top pair production cross section and the charge asymmetry at the LHC. This enhancement can be within the sensitivity of the 8 TeV run, such that the 2012 LHC data should be able to exclude a large class of models of heavy new physics or provide hints for its presence. The same new physics implies a contribution to the forward-backward asymmetry in bottom pair production at low invariant masses of order a permil at most.