Version 1.3.0 is an update of Sherpa which contains bugfixes and new features.

Sherpa 1.3.0

Version 1.3.0 is an update of Sherpa which contains bugfixes and new features. Please see the Changelog below for a complete summary. If you would like to be informed about patches and newer releases, please subscribe to our announcement mailing list.

Download

The Sherpa package can be downloaded here:

In can also be accessed via git using

  • the web interface
  • or git clone -b rel-1-3-0 https://gitlab.com/sherpa-team/sherpa.git for a local clone.

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.

References

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.

Examples and Results

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.

We also provide a public gallery of results obtained with this version of Sherpa. There you can find comparisons to experimental data and to the previous version of Sherpa, as well as studies of systematics especially with respect to ME+PS merging.

Patches/known problems/known bugs/FAQs

All known problems/questions and their solutions can be found on our issue tracker (please log in using the given details). If you encounter any problem while installing or running Sherpa, please open a new issue in the tracker.

Changelog

Bugfixes w.r.t. Version 1.2.3 + patches

Several bugs have been fixed in all parts of the event generation. We recommend upgrading to this newest version where possible.

  • Improved kinematics routines for the CSS
    The kinematics (re)construction algorithm of the parton shower has been simplified, leading to numerically more stable simulations. This becomes relevant in particular for configurations with low-virtuality t-channel propagators.
  • Improved integration routines in Comix
    Comix' recursive phase-space generator has been improved by taking more information about currents and connected vertices into account. This is most helpful for processes with many massive propagators.
  • Overhaul of internal interpreter
    Algebraic expression evaluation in the internal interpreter was made more robust. Several bugs regarding the identification of unary minus signs have been fixed.

New features/Improvements

  • Enhance observable
    It is now possible to enhance the generation of phase-space points according to the differential distribution of the process in a particular observable. For details, please refer to the online manual.
  • Local definition of ME generator
    A new option was introduced to define the desired matrix-element generator process-by-process. This allows, for example, to combine Amegic for the lowest multiplicity with Comix for all higher multiplicities, which becomes relevant in MENLOPS simulations with a large number of jets.
  • HepMC output for NLO events
    All parts of an NLO matrix element level calculation can be written out in the HepMC format. In particular, correlated real and subtraction events are written out with the same event number, such that their correlation can be taken into account in the analysis.