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What is Comix ?

Comix is a multi-leg tree-level Matrix Element generator, based on the color dressed Berends-Giele recursive relations (see references). Comix is designed to cope with especially large numbers of external legs. It employs a new algorithm to recursively compute phase space weights and can be run in multithreaded mode to make better use of multicore processors and multiprocessor machines. The original publication can be found here.

Why should I use Comix ?

Comix is a useful supplement to existing ME generators such as AMEGIC++ in the high multiplicity regime. Due to the usage of colour sampling it is easy to interface with existing parton shower simulations and can hence be employed for an ME-PS merging algorithm. Check this page for a comparison of cross sections, ME evaluation times and phasespace performance. You might also want to have a look at arXiv:0808.3672 [hep-ph] and the original publication.

How do I obtain Comix ?

Comix is shipped with the Sherpa event generator starting from Version 1.2. An older version of the code is also available as a standalone package from here.

How do I run Comix ?

Comix uses the Sherpa input structure. More information on corresponding parameters is found in the manual on the Sherpa home page and in the man and info pages. Example runcards are shipped with the code. They are located in the Examples/ subdirectory of the package.


Comix is free software. You can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation. You should have received a copy of the GNU General Public License along with the source for Comix; see the file COPYING. Comix is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

Comix was created during the Marie Curie RTN's HEPTOOLS and MCnet. The MCnet Guidelines apply, see file GUIDELINES.


Color dressed recursive relations: JHEP 08 (2006) 062
Berends-Giele recursion: Nucl. Phys. B306 (1986) 759
Spinor basis: Nucl. Phys. B274 (1986) 1
Polarization vectors: Phys. Rev. D59 (1999) 016007
Complex mass scheme: Nucl. Phys. B560 (1999) 33
Phase space recursion: Nucl. Phys. B9 (1969) 568

Technical Details

Interaction vertices have been tested versus AMEGIC++ on a point by point basis in a variety of processes, see this page.