First analysis of world polarized DIS data with small-$x$ helicity evolution

TL;DR

This paper analyzes world polarized deep-inelastic scattering data at small x using a Monte Carlo approach within the polarized quark dipole formalism, successfully describing double-spin asymmetries and predicting the g_1 structure function at smaller x, with implications for future Electron-Ion Collider measurements.

Contribution

First application of small-x helicity evolution to describe polarized DIS data, enabling predictions for g_1 at very small x from first-principles QCD.

Findings

Double-spin asymmetries at x<0.1 are well described by small-x evolution.

Predictions for g_1 structure function at x much smaller than 0.1.

Extraction of flavor helicity PDFs at small x.

Abstract

We present a Monte Carlo based analysis of the combined world data on polarized lepton-nucleon deep-inelastic scattering at small Bjorken $x$ within the polarized quark dipole formalism. We show for the first time that double-spin asymmetries at $x<0.1$ can be successfully described using only small-$x$ evolution derived from first-principles QCD, allowing predictions to be made for the $g_1$ structure function at much smaller $x$. Anticipating future data from the Electron-Ion Collider, we assess the impact of electromagnetic and parity-violating polarization asymmetries on $g_1$ and demonstrate an extraction of the individual flavor helicity PDFs at small $x$.