Abstract
We present MAPFF1.0, a determination of unpolarised charged-pion fragmentation functions (FFs) from a set of single-inclusive $e^+e^-$ annihilation and lepton-nucleon semi-inclusive deep-inelastic-scattering (SIDIS) data. FFs are parametrised in terms of a neural network (NN) and fitted to data exploiting the knowledge of the analytic derivative of the NN itself w.r.t. its free parameters. Uncertainties on the FFs are determined by means of the Monte Carlo sampling method properly accounting for all sources of experimental uncertainties, including that of parton distribution functions. Theoretical predictions for the relevant observables, as well as evolution effects, are computed to next-to-leading order (NLO) accuracy in perturbative QCD. We exploit the flavour sensitivity of the SIDIS measurements delivered by the HERMES and COMPASS experiments to determine a minimally-biased set of seven independent FF combinations. Moreover, we discuss the quality of the fit to the SIDIS data with low virtuality $Q^2$ showing that, as expected, low-$Q^2$ SIDIS measurements are generally harder to describe within a NLO-accurate perturbative framework.
Highlights
Unpolarized collinear fragmentation functions (FFs) [1] encode the nonperturbative mechanism, called hadronization, that leads a fast on shell parton to inclusively turn into a fast hadron moving along the same direction
This paper presents a determination of the FFs of charged pions, called MAPFF1.01, in which the most updated single-hadron production in electron-positron annihilation (SIA) and semi-inclusive deep-inelastic-scattering (SIDIS) measurements are analyzed to next-to-leading order (NLO) accuracy in perturbative quantum chromodynamics (QCD)
V C we study the impact of some specific datasets: we discuss the origin of the difficulty in fitting SIA charm-tagged data, we investigate the impact of the SIDIS data on FFs, and we study the dependence of the fit quality on the low-Q cut on the SIDIS data
Summary
Unpolarized collinear fragmentation functions (FFs) [1] encode the nonperturbative mechanism, called hadronization, that leads a fast on shell parton (a quark or a gluon) to inclusively turn into a fast hadron moving along the same direction. Global determinations of FFs including recent measurements for all of the three processes mentioned above have become available [2]; in the second respect, determinations of FFs accurate to next-to-next-to-leading order (NNLO) [3,4] or including all-order resummation [5] have been presented, albeit based on SIA data only; in the third respect, determinations of FFs using modern optimization techniques that minimize parametrization bias [4], or attempting a simultaneous determination of the parton distribution functions (PDFs) [6], have been performed These three aspects have been investigated for the FFs of the kaon [4,6,7,8,9,10]. VI we provide a summary of our results and outline possible future developments
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