Eur. Phys. J. C (2008) 58: 639-707
https://doi.org/10.1140/epjc/s10052-008-0798-9

Special Article - Tools for Experiment and Theory

Herwig++ physics and manual

¹ Institut für Theoretische Physik, Universität Karlsruhe, Karlsruhe, Germany
² IPPP, Department of Physics, Durham University, Durham, UK
³ Centre for Particle Physics and Phenomenology, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
⁴ Cavendish Laboratory, University of Cambridge, Cambridge, UK
⁵ Physics Department, CERN, Geneva, Switzerland
⁶ School of Physics and Astronomy, University of Manchester, Manchester, UK

^* e-mail: herwig@projects.hepforge.org

Received: 1 September 2008
Published online: 20 November 2008

Abstract

In this paper we describe version 2.2, a general-purpose Monte Carlo event generator for the simulation of hard lepton-lepton and hadron-hadron collisions. A number of important hard scattering processes are available, together with an interface via the Les Houches Accord to specialized matrix element generators for additional processes. The simulation of Beyond the Standard Model (BSM) physics includes a range of models and allows new models to be added by encoding the Feynman rules of the model. The parton-shower approach is used to simulate initial- and final-state QCD radiation, including colour coherence effects, with special emphasis on the correct description of radiation from heavy particles. The underlying event is simulated using an eikonal multiple parton-parton scattering model. The formation of hadrons from the quarks and gluons produced in the parton shower is described using the cluster hadronization model. Hadron decays are simulated using matrix elements, where possible including spin correlations and off-shell effects.