Recent developments in POWHEG

TL;DR

The paper reviews recent developments in POWHEG, a method for interfacing NLO QCD calculations with parton-shower generators, highlighting its positive-weight event generation and independence from the shower program. It clarifies the theoretical framework with constructs like R_s and a modified Born term Bbar to achieve NLO accuracy, and discusses how POWHEG compares to MC@NLO. A central contribution is the POWHEG BOX, an automation framework based on FKS subtraction that enables rapid implementation of complex NLO calculations, demonstrated with processes such as Z+jet and Higgs production via vector-boson fusion. The work underscores improved understanding of the method, its broader applicability, and its potential to streamline future NLO interfacing efforts.

Abstract

I review recent developments in POWHEG, a method for interfacing parton-shower generators with NLO QCD computations. I illustrate recent progress in understanding several features of the method, and in clarifying similarity and differences with respect to MC@NLO. Furthermore, I briefly describe a recently introduced framework, the POWHEG BOX, that allows the automatic POWHEG implementation of any given NLO calculation, and has been recently applied to Z+jet production and to Higgs production via vector-boson fusion.

Figures (2)

• Figure 1: Left: rapidity distribution of the hardest jet relative to the Higgs rapidity. The highest curve at $y=0$ is POWHEG$+$ PYTHIA, next is POWHEG$+$ HERWIG, then MC@NLO and then HERWIG alone. Right: MC@NLO, with $\bar{B}$ replaced by $B$ in the generation of ${\@fontswitch\mathcal{S}}$ events.
• Figure 2: Left: rapidity distribution of the hardest jet relative to the Higgs rapidity. The highest curve at $y=0$ is POWHEG$+$ PYTHIA, next is POWHEG$+$ HERWIG, then MC@NLO and then HERWIG alone. Right: MC@NLO, with $\bar{B}$ replaced by $B$ in the generation of ${\@fontswitch\mathcal{S}}$ events.