HAPS Collaboration (Hadron and Partonic Structure Collaboration) is a research collaboration focused on precision QCD studies of hadron and partonic structure.
Its scientific program includes global analyses and phenomenological investigations of unpolarized and polarized parton distribution functions, fragmentation functions, spin-dependent observables, and the impact of present and future measurements, particularly those relevant to the Electron-Ion Collider.
The collaboration aims to advance a more quantitative understanding of hadron structure by combining modern theoretical frameworks, data-driven methodologies, and precision phenomenology.
HAPS-pPDF1.0 is a polarized parton distribution function set developed within the HAPS Collaboration
Toward Precision Helicity PDFs from Global DIS and SIDIS Fits with Projected EIC Measurements Hamzeh Khanpour, Maryam Soleymaninia, Majid Azizi, Michael Klasen, Hadi Hashamipour, Maral Salajegheh, and Ulf-G. Meißner
- Title: Toward Precision Helicity PDFs from Global DIS and SIDIS Fits with Projected EIC Measurements
- Authors: Hamzeh Khanpour, Maryam Soleymaninia, Majid Azizi, Michael Klasen, Hadi Hashamipour, Maral Salajegheh, and Ulf-G. Meißner
- arXiv: https://arxiv.org/abs/2602.17298
- INSPIRE: https://inspirehep.net/literature/3121626
- DOI: https://doi.org/10.1103/wc54-mnfh
- LHAPDF grids: https://github.com/HAPS-Collaboration/HAPS-pPDF1.0/
HAPS-pPDF1.0 provides polarized proton PDFs extracted from a global analysis of longitudinally polarized inclusive DIS and charge-separated SIDIS data, including projected Electron-Ion Collider SIDIS pseudodata.
HAPS-hFF1.0 is an unidentified charged-hadron fragmentation function set developed within the HAPS Collaboration.
Revisiting Unidentified Charged-Hadron Fragmentation Functions with Modern COMPASS SIDIS Multiplicities Maryam Soleymaninia, Hamzeh Khanpour, Hubert Spiesberger, Majid Azizi, Michael Klasen, and Hadi Hashamipour
- Title: Revisiting Unidentified Charged-Hadron Fragmentation Functions with Modern COMPASS SIDIS Multiplicities
- Authors: Maryam Soleymaninia, Hamzeh Khanpour, Hubert Spiesberger, Majid Azizi, Michael Klasen, and Hadi Hashamipour
- arXiv: https://arxiv.org/abs/2605.31325
- INSPIRE: https://inspirehep.net/literature/3162974
- DOI:
- LHAPDF grids: https://github.com/HAPS-Collaboration/HAPS-hFF1.0
HAPS-hFF1.0 provides unidentified charged-hadron fragmentation functions extracted from a global QCD analysis of single-inclusive electron-positron annihilation data together with modern COMPASS semi-inclusive deep-inelastic scattering multiplicities. The analysis includes both NLO and NNLO extractions and studies the impact of the updated COMPASS SIDIS measurements on the flavor separation and perturbative stability of charged-hadron fragmentation functions.
HAPS-PiFF1.0 and HAPS-KaFF1.0 are charged-pion and charged-kaon fragmentation function sets developed within the HAPS Collaboration.
Modern Determination of Pion and Kaon Fragmentation Functions from SIA and High-Precision COMPASS SIDIS Multiplicities Maryam Soleymaninia, Hamzeh Khanpour, Hubert Spiesberger, Majid Azizi, Michael Klasen, and Hadi Hashamipour
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Title: Modern Determination of Pion and Kaon Fragmentation Functions from SIA and High-Precision COMPASS SIDIS Multiplicities
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Authors: Maryam Soleymaninia, Hamzeh Khanpour, Hubert Spiesberger, Majid Azizi, Michael Klasen, and Hadi Hashamipour
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DOI:
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LHAPDF grids:
- HAPS-PiFF1.0: https://github.com/HAPS-Collaboration/HAPS-PiFF1.0
- HAPS-KaFF1.0: https://github.com/HAPS-Collaboration/HAPS-KaFF1.0
HAPS-PiFF1.0 and HAPS-KaFF1.0 provide charged-pion and charged-kaon fragmentation functions extracted from a global QCD analysis of single-inclusive electron-positron annihilation data together with charge-separated semi-inclusive deep-inelastic scattering multiplicities from HERMES and COMPASS.
A central goal of this analysis is to incorporate the modern COMPASS SIDIS input, including the COMPASS 2025 proton-target multiplicities and the COMPASS 2026 revised isoscalar-target multiplicities, into a common charged-pion and charged-kaon fragmentation-function framework. The resulting fits assess the impact of these high-precision measurements on flavor separation, including favored and unfavored light-quark fragmentation, as well as strange-to-kaon fragmentation channels.
The analysis includes both NLO and NNLO extractions. The resulting HAPS-PiFF1.0 and HAPS-KaFF1.0 Monte Carlo replica sets are provided in the standard LHAPDF format.
