Abstract
We present theoretical predictions for the production of top-quark pairs in association with jets at the LHC including electroweak (EW) corrections. First, we present and compare differential predictions at the fixed-order level for tbar{t} and tbar{t}+text {jet} production at the LHC considering the dominant NLO EW corrections of order {{mathcal {O}}}(alpha _mathrm {s}^2 alpha ) and {{mathcal {O}}}(alpha _mathrm {s}^3 alpha ) respectively together with all additional subleading Born and one-loop contributions. The NLO EW corrections are enhanced at large energies and in particular alter the shape of the top transverse momentum distribution, whose reliable modelling is crucial for many searches for new physics at the energy frontier. Based on the fixed-order results we motivate an approximation of the EW corrections valid at the percent level, that allows us to readily incorporate the EW corrections in the MePs@Nlo framework of Sherpa combined with OpenLoops. Subsequently, we present multi-jet merged parton-level predictions for inclusive top-pair production incorporating NLO QCD + EW corrections to tbar{t} and tbar{t}+text {jet}. Finally, we compare at the particle-level against a recent 8 TeV measurement of the top transverse momentum distribution performed by ATLAS in the lepton + jet channel. We find very good agreement between the Monte Carlo prediction and the data when the EW corrections are included.
Highlights
Theoretical predictions for ttproduction at hadron colliders are very advanced
Considering ttproduction in association with additional jets, for tt + jet [11,12], tt + 2 jets [13,14,15,16,17] and even tt + 3 jets [18] higher-order corrections are known at NLO QCD reducing the otherwise significant theoretical uncertainties in the modelling of top-pair plus multi-jet signatures, relevant for ttH and new-physics searches
Beyond the on-shell approximation, NLO QCD corrections for combined ttproduction and decay have first been studied in the narrow-width-approximation (NWA) [6,19,20] and later fully off-shell based on the W +W −bbfinal-state with off-shell leptonic [21,22,23,24,25] and semi-leptonic [26] decays
Summary
Theoretical predictions for ttproduction (in association with jets) at hadron colliders are very advanced. In this paper we present multi-jet merged predictions for top-pair production including QCD and EW corrections.
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