Fragmentation Functions

Fragmentation Functions (FFs) encode the long-distance dynamics of the interactions among quarks and gluons which lead to their hadronisation in a hard-scattering process.

In order to obtain theoretical predictions for the observables involving identified hadrons in the final state, FFs have to be convoluted with partonic cross-sections encoding instead the short-distance dynamics of the interaction. If the hard-scattering process is initiated by nucleons, additional convolutions with the Parton Distribution Functions (PDFs) are required.

While partonic cross-sections can be computed perturbatively in QCD, FFs cannot, which puts them on the same footing as PDFs. Therefore, FFs need to be determined from a global analysis of a suitable set of experimental measurements, possibly from a variety of hard-scattering processes.

My collaborators and I are currently determining a set of FFs based on Machine Learning from a large set of processes like the Semi-Inlcusive Deep Inelastic Scattering (SIDIS) for both identified and unidentified charged hadrons from COMPASS and HERMES, Single-Inclusive hadron production data in electron-positron Annihilation (SIA), etc.

We had so far two releases:

• MAPFF1.0: A determination of unpolarised pion fragmentation functions using semi-inclusive deep-inelastic-scattering data.
• MAPFF1.0’: Pion and kaon fragmentation functions at next-to-next-to-leading order.

For more information: MAP collaboration