Conference Presentation

PUBDB-2026-01040

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Physical and spurious thresholds in NNLO SIDIS hard functions

Wunder, F. (Corresponding author)DESY*

2026

Abstract: We analyze the analytic structure of the recently calculated NNLO coefficient functions for unpolarized and polarized semi-inclusive deep inelastic scattering (SIDIS). The published results contain a decomposition into several kinematic regions, reflecting threshold-like branch points that originate from the hypergeometric representation of one-loop box integrals in real and virtual corrections. While physical thresholds are dictated by unitarity, these additional thresholds are spurious analytic artifacts that cancel between contributions.By expressing the affected parts in terms of single-valued polylogarithms, we obtain a unified representation of the NNLO hard functions that is valid over the full SIDIS phase space and free of case distinctions. In this form, the separation between physical and spurious thresholds becomes manifest, and the resulting expressions are globally analytic and substantially more compact.We discuss implications for Mellin-space representations and for future systematic NLP resummation of SIDIS, where analytic control of the non-distributional threshold structure of hard functions becomes a key ingredient.

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Contributing Institute(s):

1. Theorie-Gruppe (T)

Research Program(s):

1. 611 - Fundamental Particles and Forces (POF4-611) (POF4-611)
2. DFG project G:(GEPRIS)409651613 - FOR 2926: Next Generation Perturbative QCD for Hadron Structure: Preparing for the Electron-Ion Collider (409651613) (409651613)

Experiment(s):

1. No specific instrument

Appears in the scientific report 2026

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