DIRE4Pythia is hosted by Hepforge, IPPP Durham

Welcome to the DIRE parton shower


Thanks for your interest in DIRE (short for dipole resummation), a C++ program for all-order radiative corrections to scattering processes in high-energy particle collisions. DIRE is available as plugin to the PYTHIA8 General Purpose Monte Carlo Event Generator. If you have stumbled onto this page by accident, here are pictures of puppies.

The DIRE parton shower combines dipole-shower ideas in the spirit of ARIADNE with the careful handling of collinear enhancements in classical parton showers. As such, it is a full-fledged replacement of the PYTHIA8 parton showers for lepton-lepton, lepton-hadron and hadron-hadron collisions, including a detailed treatment of mass effects.

DIRE is automatically interleaved with PYTHIA's multiple interaction model. Furthermore, PYTHIA can use DIRE in its internal merging machinery to produce CKKW-L or UMEPS merged results at leading order, or NL3 or UNLOPS merged merged results at next-to-leading order. The implementation of DIRE has been thoroughly checked against an independent implementation in the SHERPA event generator. The SHERPA implemetation is part of generator code for versions greater than 2.2.0.

The DIRE physics publication is HERE or HERE. Please cite this article (and of course the PYTHIA8 reference) if you use PYTHIA8+DIRE for your research. Recent talks about DIRE can be found here and here.

For installation instructions and code documentation, please consult the corresponding items in the left-hand menu.


The latest version of DIRE is 2.000, published on May 2nd 2017. This version is compatible with PYTHIA versions 8.226 or higher. The code now allows for NLO corrections to the parton shower evolution, for lepton-lepton, lepton-hadron or hadron-hadron collisions. If you use these NLO functionalities, please cite arXiv:1705.00742 and arXiv:1705.00982.


You can download the most recent DIRE plugin for PYTHIA8 HERE or select a version from the downloads option in the left-hand menu.

Authors and Contact

DIRE has been developed by Stefan Höche and Stefan Prestel. For questions about the PYTHIA8 plugin code, please contact direforpythia*AT*projects*DOT*hepforge*DOT*org