A determination of the fragmentation functions of pions, kaons, and protons with faithful uncertainties

Abstract

We present NNFF1.0, a new determination of the fragmentation functions (FFs) of charged pions, charged kaons, and protons/antiprotons from an analysis of single-inclusive hadron production data in electron–positron annihilation. This determination, performed at leading, next-to-leading, and next-to-next-to-leading order in perturbative QCD, is based on the NNPDF methodology, a fitting framework designed to provide a statistically sound representation of FF uncertainties and to minimise any procedural bias. We discuss novel aspects of the methodology used in this analysis, namely an optimised parametrisation of FFs and a more efficient minimisation strategy, and validate the FF fitting procedure by means of closure tests. We then present the NNFF1.0 sets, and discuss their fit quality, their perturbative convergence, and their stability upon variations of the kinematic cuts and the fitted dataset. We find that the systematic inclusion of higher-order QCD corrections significantly improves the description of the data, especially in the small-z region. We compare the NNFF1.0 sets to other recent sets of FFs, finding in general a reasonable agreement, but also important differences. Together with existing sets of unpolarised and polarised parton distribution functions (PDFs), FFs and PDFs are now available from a common fitting framework for the first time.

Heavy-flavor parton distributions without heavy-flavor matching prescriptions

“…[71] within a FONLL-inspired GM-VFNS framework). While typically the uncertainties in fragmentation function analyses are larger than in pdf ones, recent advances in this subject have introduced NNLO QCD precision into global fragmentation function fits [72,73] which suggest that a more refined treatment of HFMPs in fragmentation functions may also be beneficial.…”

Charged hadron fragmentation functions from collider data

“…, , and . Among the most recent studies, the HKKS16 [16], JAM16 [17], and NNFF1.0 [18] analyses are based on SIA data only. A global determination of the charged pion and kaon FFs was carried out in Refs.…”

Measurements of fragmentation functions and implications for semi-inclusive deep-inelastic scattering

“…Altogether, single inclusive hadron production in e + e − annihilation is presently the best understood process among all the e + e − annihilation data on fragmentation functions. A grain of salt might be an apparently not well understood radiative correction as that applied in the data analysis (up to 30%) had to be undone in the phenomenology [29]. Furthermore, single-hadron production is neither well-suited for flavor separation of fragmentation functions nor very useful to tag quark polarization.…”