To get started first all required process libraries have to be downloaded and compiled. Further libraries can be downloaded at any time.
Now you are ready to use OpenLoops as a plugin to Sherpa or Herwig++.
Alternatively, you can interface OpenLoops to your own Monte Carlo program. A minimal Fortran90 example how this can be done is presented in the following. More detailed instructions on the OpenLoops interface can be found here.
The following minimal example loads the library for the process dd ➞ Zuu and calculates the corresponding tree and one-loop amplitude for a random phase-space point. The required library has to be downloaded before via
./openloops libinstall ppzjj
This example can also be found inside the file ./examples/OL_minimal.f90 of the OpenLoops installation and can be compiled via:
or with the SCons build system via