Sherpa 2.1.1 (Broad Peak)
Version 2.1.1 is a bugfix-release based on the second NLO version of Sherpa. A description of the issues which have been addressed can be found below. Additionally, the simulation of DIS at ep colliders has been re-validated.
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 all physics analyses. 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
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.
- A bug related to MC@NLO has been fixed. This will affect the total cross section in heavy quark production at the level of few permille.
- A bug related to parton showering in associated Higgs boson production has been fixed.
- A problem related to SQLite database locking on IBM BG/Q systems has been solved. See these instructions
- A bug related to CS subtraction with Comix has been fixed. This will eliminate possible large weights in events containing extremely soft gluons.
- A bug related to the QED corrections on the hard interaction accidentally being switched off has been fixed.
- A bug related to the contents of the HepMC::PdfInfo? object in MC@NLO event generation has been fixed.
- A bug in the underlying event simulation, presenting as a final state particle asymmetry, has been fixed. An update of the underlying event parameters was necessary, invalidating MPI grids generated with previous versions.
- The Python interface to access Sherpa's matrix elements has been updated and supplemented with a C++ interface.
- A bug in the CS subtraction in DRED has been fixed.
- There are no new features compared to version 2.1.0