Extraction of transverse-momentum-dependent helicity distributions of the nucleon
Abstract
We present an updated global analysis of the transverse-momentum-dependent (TMD) helicity distributions of the nucleon from measurements of the longitudinal double-spin asymmetry ALL in semi-inclusive deep-inelastic scattering (SIDIS). The analysis incorporates target- and detected-hadron-mass corrections, next-to-next-to-leading-order matching in the small-bT operator product expansion, and an improved treatment of correlated systematic uncertainties. The present data constrain the up- and down-quark helicity TMDs, whereas the sea-quark and gluon distributions remain weakly constrained. After integration over transverse momenta up to the hard scale, the up- and down-quark distributions agree with collinear helicity distributions within uncertainties. Using the extracted TMDs and the Wandzura-Wilczek-type approximation, we predict the cosϕh modulation of ALL and find agreement with the HERMES and CLAS measurements. We also provide predictions for SIDIS ALL at CLAS12 and for longitudinal single-spin asymmetries in W± production with leptonic decays at STAR kinematics. An impact study with pseudodata for the proposed Electron-Ion Collider in China (EicC) indicates substantial potential to improve constraints on helicity TMDs at intermediate x, including the presently weakly constrained sea-quark sector.
Related
- Deep-neural-network extraction of unpolarized transverse-momentum-dependent parton distributions in bT space from Drell-Yan data
- Gravitational transverse momentum dependent distributions for the gluons
- Recent Advances in Transverse-Momentum--Dependent Distributions in Lattice QCD
- Transverse momentum dependent parton distributions at small x
- Analytic next-to-leading-order helicity cross sections for vector-boson production at finite transverse momentum
BibTeX
@misc{yang2026extraction,
title = {{Extraction of transverse-momentum-dependent helicity distributions of the nucleon}},
author = {Ke Yang and Tianbo Liu and Bo-Qiang Ma and Peng Sun and Yuxiang Zhao and Yiyu Zhou},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.31290},
eprint = {2610.31290},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.31290},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Extraction of transverse-momentum-dependent helicity distributions of the nucleon
AU - Ke Yang
AU - Tianbo Liu
AU - Bo-Qiang Ma
AU - Peng Sun
AU - Yuxiang Zhao
AU - Yiyu Zhou
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2610.31290
UR - https://arxiv.org/abs/2610.31290
AB - We present an updated global analysis of the transverse-momentum-dependent (TMD) helicity distributions of the nucleon from measurements of the longitudinal double-spin asymmetry A_LL in semi-inclusive deep-inelastic scattering (SIDIS). The analysis incorporates target- and detected-hadron-mass corrections, next-to-next-to-leading-order matching in the small-b_T operator product expansion, and an improved treatment of correlated systematic uncertainties. The present data constrain the up- and down-quark helicity TMDs, whereas the sea-quark and gluon distributions remain weakly constrained. After integration over transverse momenta up to the hard scale, the up- and down-quark distributions agree with collinear helicity distributions within uncertainties. Using the extracted TMDs and the Wandzura-Wilczek-type approximation, we predict the cosϕ_h modulation of A_LL and find agreement with the HERMES and CLAS measurements. We also provide predictions for SIDIS A_LL at CLAS12 and for longitudinal single-spin asymmetries in W^± production with leptonic decays at STAR kinematics. An impact study with pseudodata for the proposed Electron-Ion Collider in China (EicC) indicates substantial potential to improve constraints on helicity TMDs at intermediate x, including the presently weakly constrained sea-quark sector.
ER -