HERWIG 6.5 Release Note
G Corcella, IG Knowles, G Marchesini, S Moretti, K Odagiri, P Richardson, MH Seymour, BR Webber
TL;DR
HERWIG 6.5 consolidates major interoperability and physics improvements, notably the Les Houches interface for external matrix-element generators, expanded SM and MSSM Higgs production in lepton collisions, and spin-correlated decays including R-parity violating channels. It adds updated interfaces (ISAWIG, HDECAY, MC@NLO) and a suite of misc fixes and performance enhancements, including Jimmy-based underlying-event support and small-x PDF controls. This release marks the final major Fortran HERWIG version, signaling a shift to the new C++ generator HERWIG++ for future development. Collectively, these changes broaden tool interoperability, improve accuracy for key processes, and stabilize the codebase for next-generation event generation.
Abstract
A new release of the Monte Carlo program HERWIG (version 6.5) is now available. The main new features are: support for the Les Houches interface to matrix element generators; additional SM and MSSM Higgs processes in lepton collisions; additional matrix elements for the spin correlation algorithm; a new version of the ISAWIG interface; interface to the MC@NLO program for heavy quark, Higgs and vector boson production in hadron collisions. boson pair production in hadron collisions. This is planned to be the last major release of Fortran HERWIG. Future developments will be implemented in a new C++ event generator, HERWIG++.