Practical improvements and merging of POWHEG simulations for vector boson production

TL;DR

This paper extends POWHEG NLOPS simulations for vector boson production to include matrix element corrections, introduces a faithful implementation of MENLOPS in hadronic collisions, and explores merging techniques with phase space partitioning.

Contribution

It provides the first exact implementation of MENLOPS formalism for hadronic collisions and develops a merging method based on phase space partitioning.

Findings

Predictions depend on the unphysical merging scale.

Comparisons with Tevatron and LHC data show good agreement.

Merging preserves NLO accuracy of inclusive observables.

Abstract

In this article we generalise POWHEG next-to-leading order parton shower (NLOPS) simulations of vector boson production and vector boson production in association with a single jet, to give matrix element corrected MENLOPS simulations. In so doing we extend and provide, for the first time, an exact and faithful implementation of the MENLOPS formalism in hadronic collisions. We also consider merging the resulting event samples according to a phase space partition defined in terms of an effective jet clustering scale. The merging scale is restricted such that the component generated by the associated production simulation does not impact on the NLO accuracy of inclusive vector boson production observables. The dependence of the predictions on the unphysical merging scale is demonstrated. Comparisons with Tevatron and LHC data are presented.