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16th COMPASS Analysis Phase international mini-workshop (COMAP-XVI)

21–25 May 2026
CERN
Europe/Zurich timezone

Session

Session 3

22 May 2026, 14:30
892/1-B09 (CERN)

892/1-B09

CERN

30
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Conveners

Session 3: Helicity PDF: measurements and extractions

  • Bakur Parsamyan (AANL, Turin section of INFN and CERN)
  • ALESSIA BONGALLINO (Universidad del PaÍs Vasco (UPV/EHU))

Presentation materials

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  1. 11. Mapping the helicity transverse momentum distribution: status and perspectives
    Alessia Bongallino (University of the Basque Country UPV/EHU)
    22/05/2026, 14:30

    The helicity parton distribution function plays a crucial role in better understanding the quark and gluon spin structure of the proton. We study the transverse momentum dependence of the quark helicity distribution by analysing experimental data on semi-inclusive deep inelastic scattering off longitudinally polarised targets provided by the HERMES Collaboration. The fit is performed at...

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  2. 16. Next-to-Next-to-Leading Order Global Analysis of Polarized Parton Distribution Functions
    Ignacio Borsa (Tübingen University)
    22/05/2026, 15:00

    The study of the internal spin structure of the proton in terms of the contributions from quarks, anti-quarks and gluons, is a key focus of modern particle physics. These contributions can be described in terms of the longitudinally polarized parton distribution functions (pPDFs) or helicity PDFs, which are probed in high-energy scattering processes involving polarized nucleons.
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  3. 7. Longitudinal Spin Structure of the Proton in SIDIS at COMPASS
    Dr Bakur Parsamyan (AANL, Turin section of INFN and CERN)
    22/05/2026, 15:50
    1

    The longitudinal spin structure of the proton is studied with the COMPASS experiment using SIDIS data collected with a longitudinally polarized NH$3$ target and positive muon beams of 160 GeV/$c$ in 2007 and 200 GeV/$c$ in 2011. The analysis focuses on the double-spin asymmetry $A{LL}$, providing access to the spin-dependent structure function $g_1$, together with azimuthal asymmetries...

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  4. 10. Longitudinal Target-Spin Effects in SIDIS with CLAS12
    Harut Avakian (Jefferson Lab)
    22/05/2026, 16:20

    We present recent CLAS12 studies of target longitudinal-spin effects in semi-inclusive deep-inelastic scattering. The results provide new constraints on spin-dependent TMDs and the longitudinal spin structure of the nucleon.

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  5. 17. Longitudinal spin asymmetries at HERMES
    Gunar Schnell
    22/05/2026, 16:50

    In this contribution, we will recall the analysis details leading to the publication of the HERMES longitudinal-spin asymmetries, with a focus on A_LL in semi-inclusive DIS.

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  6. 1. Extraction of the Helicity TMD PDF g1
    ALESSIA BONGALLINO (Universidad del PaÍs Vasco (UPV/EHU))
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