The MC@NLO 2.2 Event Generator

TL;DR

MCatNLO 2.2 documents a practical implementation that integrates NLO QCD matrix elements with a HERWIG-based parton shower using the Les Houches interface. It details a two-executable workflow (NLO to generate an event file and MC to shower) and a wide set of production processes, including Higgs, single vector bosons, vector boson pairs, and heavy quark pairs. The manual covers file structures, dependencies on PDFs, shell script-based workflows, and the handling of negative-weight events, while clarifying differences from previous versions and decays treatment. It also provides guidance on running with or without shell scripts, prerequisites for HERWIG, and how to configure inputs and outputs for consistent NLO+shower simulations across a range of collider scenarios.

Abstract

This is the user's manual of MC@NLO 2.2. 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. Processes available in this version include the hadroproduction of Higgs bosons, single vector bosons, vector boson pairs, and heavy quark-antiquark pairs. This document is self-contained, but we emphasise the main differences with respect to previous versions.