Implementing a PDF model

If you have followed the installation instructions, you can follow this tutorial to use Colibri to implement the Les Houches parametrisation model, which is described in this section.

This parametrisation is simple enough for us to exemplify the use of Colibri, while still being realistic enough that this tutorial can be used as a template for other, more complex models.

First, we will provide a description of the Les Houches model, establishing how many and which are the free parameters to be fitted. Since Colibri works in the evolution basis, we will also describe in detail what the PDFs to be fitted look like in this basis.

After establishing how the Les Houches model looks like, we will implement it in Colibri.

This model can then be used to perform fits and run closure tests (see the tutorials section).

• Les Houches Parametrisation
• Implementing a Model in Colibri

Note

If you want to run Colibri fits with a model that has already been implemented, or want to have a look at the implementation of a more complex model, you can head to this section.