Towards loop splitting amplitudes and collinear factorisation breaking

The groundbreaking discovery of the Higgs boson at the Large Hadron Collider rang the bell for the beginning of a new era of particle physics. Naturally, the ever increasing precision data from experiments demand precise theory predictions for many observables to test the ultimate validity of the Standard Model (SM); any significant deviations from the SM predictions will hint for new physics. Quantum chromodynamics (QCD) being the most fascinating non-Abelian gauge theory provides a promising platform in achieving this goal through higher order perturbative computations in powers of the strong coupling. Process independent singular elements associated to QCD factorisation of scattering amplitudes in both soft and collinear limits, also known as splitting amplitudes, are the key elements in organising and automating these higher order calculations for the theory prediction of a general jet observable. So, the high relevance of these splitting amplitudes strongly motivates the researcher for an ambitious proposal on further improving their theoretical accuracy. In particular, through this proposal the researcher will investigate the soft-collinear splitting amplitudes required to predict a jet observable at next-to-next-to-next-to-leading order (N3LO). The researcher will also be exploring the intriguing concepts of collinear factorisation breaking and its effect on the prediction of an experimental measurable quantity. Upon successful, this project will contribute to the purpose of bringing down the theory uncertainties to 1\% level together with many new ideas and techniques which will assist the researcher to create an independent future career and contribute to tighten the grip on N3LO calculation tools.