Highly accurate QCD matrix elements at low computational cost

Collider physics is about investigating the smallest constituents of matter and the natural laws that govern their behaviour. These can mathematically be described by the Standard Model (SM) of particle physics. The world´s largest scientific experiment, the Large Hadron Collider, has been designed to explore this theory.

The precision of its data is unprecedented, and well beyond expectations. To get the most out of the data, it needs to be compared to theory predictions that are as least as accurate.

Due to the complexity of the strong interactions as described by the Standard Model, the computational cost of such highly accurate predictions is enormous, sometimes exceeding 100 000 CPU hours for a single process with a single set of parameters.

Novel calculation methods need to be considered, that are much faster than what is currently used to be able to keep up with the demand.

The purpose of this project is to re-evaluate the most time-consuming and complex parts of the current predictions, i.e., the evaluation of the so-called matrix elements.

The new idea is to expand the matrix elements in the inverse of the number of different charges ("colours") and to systematically remove most, but not all, suppressed contributions.

This would remove one of the major hurdles of LHC´s future utility: it ensures that current and future CPU-intensive improvements in the predictions are not in vain, allowing for the scrutiny of the SM at unprecedented levels.