This section details the external codes which are useful in producing theory predictions.
“What does any of this have to do with apples?”
There are many ingredients that go into a PDF fit. For example, one must generate the partonic cross sections for use in the fit, convert these predictions into a format that is suitable for PDF fits, i.e. the format must be suitable for on-the-fly convolutions, and evolve the PDFs according to the DGLAP equations. To perform each of these steps, different codes are used. In this section various external codes that you will frequently encounter are described.