High multiplicity processes at NLO with BlackHat and Sherpa

TL;DR

This paper reviews recent advancements in NLO QCD predictions for vector boson plus jets production at hadron colliders, emphasizing computational tools BlackHat and SHERPA, and their application to background estimation in new physics searches.

Contribution

It introduces new methods for high-multiplicity loop calculations and improved handling of color degrees of freedom in NLO multi-jet predictions.

Findings

Enhanced precision in vector boson plus four jets predictions

Application of NLO predictions to CMS background estimation

Development of new computational techniques for high-multiplicity loops

Abstract

In this contribution we review recent progress with fixed-order QCD predictions for the production of a vector boson in association with jets at hadron colliders, using the programs BlackHat and SHERPA. We review general features of next-to-leading-order (NLO) predictions for the production of a massive vector boson in association with four jets. We also discuss how precise descriptions of vector-boson production can be applied to the determination of backgrounds to new physics signals. Here we focus on data-driven backgrounds to a missing-energy-plus-jets search performed by CMS. Finally, we review recent progress in developing theoretical tools for high-multiplicity loop-computation within the BlackHat-library. In particular, we discuss methods for handling the color degrees of freedom in multi-jet predictions at NLO.