Soft function Simulation and Evaluation of Real and Virtual Emissions for Non-GLobal observables

To facilitate the resummation of non-global logarithms and thereby enhancing theoretical predictions for collider phenomenology, I propose a project to calculate NNLO (order alpha_s^2) soft functions for non-global observables in Soft-Collinear Effective Theory (SCET), using semi-numerical methods. The proposed framework consists of two steps: First, the universal structure of soft and collinear divergences in Quantum Chromodynamics (QCD) is analysed to isolate singularities in an observable-independent fashion, after which the remaining phase space integrations are performed numerically. The objectives of the project are the release of a public software package for use by phenomenologists, and the use of the universal divergence structure to relate different classes of observables and shed light on properties of QCD factorisation (with the equivalence of virtuality and rapidity anomalous dimensions as a concrete example).

The project is structured into six work packages:
WP1: application to SCET-1 ("energy-type") observables without clustering effects,
WP2: SCET-1 with clustering effects,
WP3: SCET-2 ("transverse momentum-type") observables,
WP4: development of a software package, and
WP5: Exploitation,
WP6: communication, dissemination, and training.

The project is inspired by previous efforts directed at the much simpler "global" observables. As non-global observables are less investigated yet ubiquitous in collider physics (e.g. jet observables), and resummation calculations for them are only regularly performed in the large Nc limit and at low logarithmic accuracy, a framework to calculate soft functions for wide swathes of observables can be of tremendous service to the community. The systematic separation of observabledependent features from universal structures can also help shed light on fundamental properties of QCD factorisation, via e.g. an observable-independent analysis of Glauber modes and their impact on factorisation.