The MC@NLO 2.0 Event Generator

TL;DR

MC@NLO 2.0 delivers a practical framework to achieve NLO QCD accuracy in event generation by matching NLO matrix elements with a HERWIG parton shower through the Les Houches interface. The workflow builds hard configurations offline, stores them in an event file, and feeds them to HERWIG for showering and hadronization, while handling negative-weight events via signed-weight summation. The package introduces a two-executable design (NLO and MC), a self-contained PDF library (with optional PDFLIB), and a detailed script-driven setup (via $MCatNLO.inputs$) to control physics parameters and running procedures, including the negative IPROC convention and underlying-event handling. This enables efficient, consistent generation of vector boson pair and heavy quark pair production events in hadron collisions, with clear guidance on installation, environment requirements, and run-time inputs for researchers and phenomenologists.

Abstract

This is the user's manual of MC@NLO 2.0. This package is a practical implementation, based upon the HERWIG event generator, of the MC@NLO formalism, which allows one to incorporate NLO QCD matrix elements consistently into a parton shower framework. The processes available in this version are those of vector boson pair and heavy quark pair production in hadron collisions. This document is self-contained, but we emphasise the main differences with respect to version 1.0.