Contact information

New version alerts

If you want to be alerted whenever a new public version is released, you can subscribe on Expect a handful such messages per year. There is no fixed schedule; new versions can appear either because a sufficient amount of changes have been accumulated over time, or because some crucial new feature or bug fix prompts action.

Bug reports and physics questions

No code is perfect, and we rely on PYTHIA users to report suspect behaviour to us. To help us in the subsequent debugging efforts, however, it is most helpful if you can present your case in as clear terms as possible. A convenient path is the following.

If you don't know whom to send the bug report to, then use the generic address

For special topics it may be faster to contact the PYTHIA person(s) most directly involved in this field. Here is a brief list of specialities
Name E-mail Topics
Christian Bierlich rope hadronization and string shoving; heavy-ion collisions; ALICE matters
Nishita Desai SUSY, SLHA, BSM
Leif Gellersen scale uncertainties; matching and merging
Ilkka Helenius photoproduction, gamma-gamma; diffraction
Philip Ilten taus, onia, configure and Makefile; LHCb matters
Leif Lönnblad heavy-ion collisions (pA and AA)
Stephen Mrenna SUSY, BSM, matching and merging; CMS matters
Stefan Prestel matching and merging, also to NLO; DIRE parton shower; ATLAS matters
Torbjörn Sjöstrand SM processes, parton showers, MPIs, colour reconnection, hadronization, core structure and utilities
Peter Skands SLHA, parton showers, MPIs, colour reconnection, hadronization, tuning; VINCIA
Marius Utheim hadronic rescattering
Note: write one email putting all relevant authors in cc, or use the list mentioned above. Never contact several persons independently on the same topic, thereby potentially leading to doublework. Abuse will have consequences.

Do note that the major collaborations, such as ATLAS and CMS, have their own Monte Carlo support groups, with a lot of experience in solving typical issues, many of which are related to the setups and interfaces created inside the collaborations. If you are a member of a major collaboration you should always turn to these groups in the first place, and only turn to us when it has been confirmed as a true problem going beyond the local installation.

You may also direct PYTHIA-related questions to us, following the same pattern as above, but note that manpower is limited, so focus on topics that do require our expertise. We cannot act as teachers of particle physics in a broader sense, however. If you are a PhD student it is the task of your supervisor to see to it that you are offered the particle physics courses you need, and to answer all general questions you may have. Summer schools can offer a most useful complement to the basic courses at you local university. In particular we would like to mention the MCnet annual Monte Carlo school for general information on the physics and usage of event generators, and the CTEQ annual summer school on QCD analysis and phenomenology.

Code contributions

In addition to bug reports, we welcome contributions of code that can be made a part of the public PYTHIA distribution. This could be the implementation of a new process or of some other physics mechanism. There are numerous such examples of external code that have been incorporated. Also feel free to propose new features you believe would improve PYTHIA, but be aware that manpower is a limiting factor. Ultimately we will have to set our own priorities.

To be successful, a contribution must not only introduce useful new functionality but also be written in a form that fits nicely into the existing PYTHIA framework. The CODINGSTYLE file in the PYTHIA distribution explains how to achieve clean and uniform style.

Feel free to consult beforehand whether a specific contribution would be welcome, so you don't waste time on something that e.g. may already be under way, or that may not fit so well. This in particular is the case if linking to external libraries are involved, since fitting a new library into the PYTHIA build procedure can be a rather delicate process, not always worth the bother.

For PhD students specifically, we offer MCnet-funded studentships of 3 - 6 months, during which you may come to Lund (or some other MCnet node) to work on a short project involving Monte Carlo event generators. This could be the implementation of a new feature into PYTHIA, the use of PYTHIA in a new context, or something else. You must have an idea yourself what you would like to work on, that preferably also would be beneficial for your PhD studies, and have the support of your thesis supervisor. See for more information how to apply!