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Revisiting unidentified charged-hadron fragmentation functions with modern COMPASS SIDIS multiplicities

Maryam Soleymaninia1,*, Hamzeh Khanpour2,1,†, Hubert Spiesberger3,‡, Majid Azizi1,§, Michael Klasen4,∥, and Hadi Hashamipour1,¶ (HAPS Collaboration)

  • *Contact author: Maryam_Soleymaninia@ipm.ir
  • †Contact author: Hamzeh.Khanpour@cern.ch
  • ‡Contact author: spiesber@uni-mainz.de
  • §Contact author: Ma.Azizi@ipm.ir
  • ∥Contact author: Michael.Klasen@uni-muenster.de
  • Contact author: H_Hashamipour@ipm.ir
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Phys. Rev. D 114, 054013 – Published 8 September, 2026

DOI: https://doi.org/10.1103/8zzz-6xkn

Abstract

We present HAPS-hFF1.0, a new global QCD analysis of unidentified charged-hadron fragmentation functions (FFs) using single-inclusive electron-positron annihilation (SIA) data together with the modern COMPASS semi-inclusive deep-inelastic scattering (SIDIS) multiplicities. The COMPASS input consists of the 2025 proton-target measurement and the revised LiD6-target multiplicities provided in the 2026 COMPASS addendum. The extraction is performed at both next-to-leading order (NLO) and next-to-next-to-leading order (NNLO), allowing us to study the perturbative stability of the QCD fit and the impact of the updated SIDIS information on the flavor structure of the FFs. The FFs are parametrized using neural networks, while experimental uncertainties are propagated through a Monte Carlo replica methodology. We find that the modern COMPASS multiplicities can be consistently described together with the SIA data and provide important charge-separated constraints on the light-quark and antiquark FFs. The comparison between the NLO and NNLO extractions indicates a stable quark-sector determination, while the gluon FF remains less directly constrained in the present SIA+SIDIS analysis. Our results highlight the importance of the modern COMPASS SIDIS multiplicities for precision studies of unidentified charged-hadron fragmentation and for future global FF determinations. The resulting HAPS-hFF1.0 replicas are publicly available in standard LHAPDF format.

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Phys. Rev. D 114, 054013– Published 8 September, 2026
  • Received 4 June 2026
  • Accepted 5 August 2026
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