Version 2.0.β2 is a pre-release of Sherpa. The main new feature compared to the 1.4.x series is the introduction of MEPS@NLO merging. This second beta release improves upon the previous one by an extension of its physics capabilities and an extensive re-validation of all features already present in the 1.4.x series. However, it is not yet fit for physics studies as it still needs tuning. Instead, it is intended to allow interested users to explore the new features. Unless major issues arise during that stage, we expect a final production release on a relatively short time scale.
If you spot any problem, please send us an email or post a ticket on trac. This will allow us to reach a mature version of the generator, suitable for physics analysis. If you would like to be informed about patches and newer releases, please subscribe to our announcement mailing list.
The Sherpa package can be downloaded here:
In can also be accessed via svn through
A Manual is included in the Manual/ directory of the tarball. It is available in the HTML and INFO format and provides extensive documentation of all parameters. It can also be found online.
The main reference describing the physics of Sherpa is JHEP02 (2009) 007. Please cite this publication if you have used Sherpa for your studies. Additionally, each run will produce a file called Sherpa_References.tex which contains information about the modules used in this run and the corresponding publications which should be referred. If in doubt, please seek the advice of the Sherpa authors.
You can find a large collection of example setups for using SHERPA in various different colliders/processes in the Examples/ directory of the tarball. They are also described in the manual.
Patches/known problems/known bugs/FAQs
- The interface to the OpenLoops one-loop engine has been updated in the SVN branch to be compatible with OpenLoop v5.
All known problems/questions and their solutions can be found on our issue tracker. If you encounter any problem while installing or running Sherpa, please open a new issue in the tracker.
- MEPS@NLO, see arXiv:1207.5030 and arXiv:1207.5031
- Hard decays, see Manual. Allows to decay unstable particles produced in the hard scattering process, optionally taking into account spin correlations. This is especially useful if higher order corrections (NLO) or multiple jet emission corrections (merged through MEPS) are to be effected upon resonant particle production only, and it is sufficient to factorise the decay through a narrow width approximation.