Parton-shower effects in electroweak WZjj production at the next-to-leading order of QCD

Barbara Jäger,Alexander Karlberg,Johannes Scheller

doi:10.1140/epjc/s10052-019-6736-1

Barbara Jäger, Alexander Karlberg + Show 1 more

Open Access

https://doi.org/10.1140/epjc/s10052-019-6736-1

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Abstract

We present an implementation of WZjj production via vector-boson fusion in the POWHEG BOX, a public tool for the matching of next-to-leading order QCD calculations with multi-purpose parton-shower generators. We provide phenomenological results for electroweak WZjj production with fully leptonic decays at the LHC in realistic setups and discuss theoretical uncertainties associated with the simulation. We find that beyond the leading-order approximation the dependence on the unphysical factorization and renormalization scales is mild. The two tagging jets are furthermore very stable against parton-shower effects. However, considerable sensitivities to the shower Monte-Carlo program used are observed for central-jet veto observables.

Highlights

Vector boson scattering (VBS) processes provide promising means for probing the gauge structure of the Standard Model’s electroweak sector
We present an implementation of W Z j j production via vector-boson fusion in the POWHEG BOX, a public tool for the matching of next-to-leading order QCD calculations with multi-purpose parton-shower generators
We provide phenomenological results for electroweak W Z j j production with fully leptonic decays at the Large Hadron Collider (LHC) in realistic setups and discuss theoretical uncertainties associated with the simulation

Summary

Introduction

Vector boson scattering (VBS) processes provide promising means for probing the gauge structure of the Standard Model’s electroweak sector. In particular observables related to the third jet, which is not present at LO and is generated purely by the parton shower, showed very large discrepancies Such discrepancies are expected to decrease when predictions at next-to-leading order (NLO) of QCD are used instead. This process has received significantly more theoretical attention than the other VBS processes due to its simpler structure As such this study did present results at LO, but discussed the matching of NLO-QCD calculations with parton showers (PS). Doing so in a public framework, we provide the tools for performing analyses of EW W Z j j production at NLO+PS accuracy and avoiding theoretical uncertainties due to an inaccurate treatment of the hard scattering process as inherent to a mere LO simulation.

Details of the implementation

Phenomenological results

Findings

Summary and conclusions z j3