Photon Fragmentation in the Antenna Subtraction Formalism

Understand

The theoretical description of photon production at particle colliders combines direct photon radiation and fragmentation processes, which can not be separated from each other for definitions of photon isolation used in experimental measurements.

• The theoretical description of these processes must account for collinear parton-photon configurations, retaining the dependence on the photon momentum fraction, and includes the parton-to-photon fragmentation functions.
• We extend the antenna subtraction method to include photon fragmentation processes up to next-to-next-to-leading order (NNLO) in QCD.
• Collinear photon radiation is handled using newly introduced fragmentation antenna functions and associated phase space mappings.