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 Pythia 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 Pythia 8 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. The implementation of Dire has been thoroughly checked against an independent implementation in the Sherpa event generator. The Sherpa implemetation is included as part of the generator code for versions greater than 2.2.0.

The Dire physics publication is arxiv:1506.05057 [hep-ph]. Please cite this article (and of course the Pythia 8 reference) if you use Pythia 8 + Dire for your research. For a more detailed introduction, code downloads, installation instructions, the source code repository and the code documentation, please consult the items in the right-hand menu.


The latest version of Dire is 2.004, published on October 14th, 2019. This version is compatible with Pythia versions 8.226 or higher. The code includes NLO corrections to the parton shower evolution, for lepton-lepton, lepton-hadron or hadron-hadron collisions, as described in arXiv:1705.00742 and arXiv:1705.00982. The more recent NLO advances for lepton-lepton collisions described in arXiv:1805.03757 are also included. The code furthermore includes the possibility to employ interated leading-order matrix element corrections (see arXiv:1706.06218) and QED multipole showering. Some documentation on how to use these features can be found in Usage in the right-hand menu.

Dire 2.003 was published on January 4th 2019. This version is compatible with Pythia versions 8.226-8.240. 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. Note that more recent NLO advances are not yet included in this release.


You can download the most recent Dire plugin for Pythia 8 from the Downloads section in the right-hand menu.


Recent talks about Dire are

Authors and Contact

Dire has been developed by Stefan Höche and Stefan Prestel. For questions about the Pythia 8 plugin code, please contact stefan*DOT*prestel*AT*thep*DOT*lu*DOT*se.