Higher-order EW corrections in ZZ and ZZj production at the LHC

Abstract

We consider the production of a pair of Z bosons at the LHC and study the inclusion of EW corrections in theoretical predictions at fixed order and based on multijet-merged parton-shower simulations. To this end we present exact NLO EW results for pp → e + e − µ + µ − , and, for the first time, for pp → e + e − µ + µ − j, and compare them to the EW virtual and NLL Sudakov approximation. We then match the exact NLO EW result to the resummed Sudakov logarithms to achieve an improved NLO EW + NLL EW exp sud result. Further, we discuss the inclusion of the above EW corrections in MePs@Nlo event simulations in the framework of the Sherpa event generator. We present detailed phenomenological predictions for inclusive ZZ and ZZj production taking into account the dominant EW corrections through the EW virtual approximation, as well as through (exponentiated) EW Sudakov logarithms.

Event Generators for High-Energy Physics Experiments

“…RECOLA has been interfaced to several public Monte Carlo generators. In SHERPA [640], the interface [641] is fully general for NLO QCD and EW corrections and was used for several NLO computations [642][643][644][645][646][647][648]. A public interface to WHIZARD 2.4.1 exists [649], while an interface to HERWIG exists but is not yet public [650].…”

Accelerating LHC event generation with simplified pilot runs and fast PDFs

“…including the matching and merging procedure. We perform the analysis in partially unweighted mode, which implies that the event weight can be modified by local K -factors [48][49][50][51], and events are hence not fully unweighted. However, we have removed the phase space biasing employed in our benchmark setups above, which is purely kinematical and does not depend on other details, in order to not also conflate this source of residual event weights with the new weight accounting for the differing scales in the unweighting and the final event sample.…”

“…In addition to intentional phase space biasing, the main sources for such retroactively incurred event weights are overweighted events, i.e. events whose weight exceeds the maximal weight used in the unweighting, and the local K -factor applied to the additional LO multiplicities in an NLO multijet-merged sample[47][48][49][50][51].…”

Electroweak radiative corrections in precision LHC measurements of W±/Z0+jets

“…However, when aiming for full particle-level simulations as accomplished by general-purpose Monte-Carlo event generators, the consistent inclusion of EW corrections to the hard-scattering processes poses a severe theoretical challenge [1], in particular in the context of multijet-merged calculations [2][3][4][5]. In , the inclusion of the virtual contributions into the matrix elements (MEs) of the involving channels can be done using a number of conventional ME provides, e.g.…”