The Large Hadron Collider smashes protons into each other at the highest energies humanity has ever engineered. Protons are a very convenient type of particle for our high-energy beams : they are plentiful, and they don’t lose (lots of) energy like electrons do when accelerated around the LHC ring. But they are not fundamental particles: they are made up of a tightly bound collection of smaller particles, and to make the most out of LHC experiments we need to understand both what we do and don’t know about the internal structure of the proton that these objects induce. We encode this through so-called parton density functions, or PDFs.
The LHAPDF C++ library is the LHC’s standard system for supplying PDF data to both experiments and theory calculations. Several years ago it was rewritten from scratch to make it more flexible and maintainable, but extensions are now needed. This project will put in place a far more complete regression-testing suite and code-coverage monitoring to ensure that these new developments preserve the current behaviours, which the whole LHC programme depends on being stable.
This project will add continuous-integration (CI) tests in the GitLab system, to ensure that all aspects of the LHAPDF calculations are tested on a scalable rota, and introduce CI testing of code quality. The intention is to ensure the stability of LHAPDF established behaviours to high precision, to give required confidence when making new releases and developing new features. The project can also include more physics-oriented work for a suitable candidate.