Constraining Proton Spin at Small x with Valence Quark Model
Abstract
Recently, a global analysis has been performed for longitudinal spin asymmetries in polarized deep inelastic scattering (DIS) processes, combining the polarized valence quark model with the large-Nc & Nf helicity evolution equations. With a three-fold reduction in the number of free parameters, the valence quark model results in a six-fold reduction of uncertainty for the resulting prediction of total parton spin inside the proton, when compared to previous analysis performed with traditional moderate-x model inspired by Born approximation. The fit based on valence quark model predicts a positive gluon hPDF and negative g1 structure function at small x. However, the resulting increase in the χ2-statistic of the fit warrants further examination into the physical uncertainty of the valence quark model, which is a work in progress. We also summarize other possibilities of future research directions towards the end of this article.
Related
- Proton GTMDs and Wigner Distributions in the Chiral Quark Soliton Model: Orbital Angular Momentum and Spin-Orbit Correlation with Sea Quarks
- Power corrections to heavy-quark spin correlations in small-x deep-inelastic scattering
- Valence-quark-core and meson-cloud effects on electromagnetic form factors of Δ baryons
- Measure of the kaon structure: generalized valence quark distribution functions and form factors
- Multi-Differential DVCS Cross Section Measurement on the Proton in the Valence Region with CLAS12
BibTeX
@misc{tawabutr2026constraining,
title = {{Constraining Proton Spin at Small $x$ with Valence Quark Model}},
author = {Yossathorn Tawabutr and Daniel Adamiak and Heikki Mäntysaari},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.16654},
eprint = {2609.16654},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.16654},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Constraining Proton Spin at Small x with Valence Quark Model
AU - Yossathorn Tawabutr
AU - Daniel Adamiak
AU - Heikki Mäntysaari
PY - 2026
DA - 2026/09/15
PB - arXiv
DO - 10.48550/arxiv.2609.16654
UR - https://arxiv.org/abs/2609.16654
AB - Recently, a global analysis has been performed for longitudinal spin asymmetries in polarized deep inelastic scattering (DIS) processes, combining the polarized valence quark model with the large-N_c & N_f helicity evolution equations. With a three-fold reduction in the number of free parameters, the valence quark model results in a six-fold reduction of uncertainty for the resulting prediction of total parton spin inside the proton, when compared to previous analysis performed with traditional moderate-x model inspired by Born approximation. The fit based on valence quark model predicts a positive gluon hPDF and negative g_1 structure function at small x. However, the resulting increase in the χ^2-statistic of the fit warrants further examination into the physical uncertainty of the valence quark model, which is a work in progress. We also summarize other possibilities of future research directions towards the end of this article.
ER -