Abstract
We present next-to-leading order (NLO) predictions including QCD and electroweak (EW) corrections for the production and decay of off-shell electroweak vector bosons in association with up to two jets at the 13 TeV LHC. All possible dilepton final states with zero, one or two charged leptons that can arise from off-shell W and Z bosons or photons are considered. All predictions are obtained using the automated implementation of NLO QCD+EW corrections in the OpenLoops matrix-element generator combined with the Munich and Sherpa Monte Carlo frameworks. Electroweak corrections play an especially important role in the context of BSM searches, due to the presence of large EW Sudakov logarithms at the TeV scale. In this kinematic regime, important observables such as the jet transverse momentum or the total transverse energy are strongly sensitive to multijet emissions. As a result, fixed-order NLO QCD+EW predictions are plagued by huge QCD corrections and poor theoretical precision. To remedy this problem we present an approximate method that allows for a simple and reliable implementation of NLO EW corrections in the MEPS@NLO multijet merging framework. Using this general approach we present an inclusive simulation of vector-boson production in association with jets that guarantees NLO QCD+EW accuracy in all phase space regions involving up to two resolved jets.
Highlights
Availability of precise theoretical predictions for V + multijet production can play a critical role for the sensitivity to new phenomena and for the interpretation of possible discoveries
next-to-leading order (NLO) QCD+EW effects for pp → V + 2 jets turn out to be completely free from the perturbative instabilities that plague NLO predictions for V + 1 jet production: the perturbative QCD expansion is very well behaved, and NLO EW corrections feature, as expected, Sudakov effects that become very large at the TeV scale, especially for V + 2 jet configurations where the highest transverse momentum is carried by the electroweak vector boson
In the TeV range, electroweak Sudakov logarithms change the shape of important kinematic distributions significantly and often yield corrections that largely exceed the intrinsic uncertainties of NLO QCD predictions
Summary
The production and off-shell decay of V + 1 jet involves a unique LO contribution of O(αSα2) and receives NLO QCD corrections of O(αS2α2) and NLO EW corrections of O(αSα3). It is important to keep in mind a somewhat counter-intuitive feature of NLO EW corrections, namely that real emission at O(αSα3) does involve photon bremsstrahlung (figure 2(b)) and V + 2 jet final states resulting from the emission of quarks through mixed QCD–EW interference terms (figure 2(c)). For the case of V + n jet production, σLO is the O(αSnα2) LO cross section, while δσQNCLOD and δσENWLO correspond to the O(αSn+1α2) and O(αSnα3) corrections, respectively. In order to identify potentially large effects due to the interplay of EW and QCD corrections beyond NLO, we present results considering the following factorised combination of EW and QCD corrections, σQNCLOD×EW = σQNCLOD. Subleading Born and photon-induced contributions of O(αSn−1α3) and O(αSn−2α4) will be investigated and partly included in our predictions
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