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

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 g1 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 g1 and demonstrate an extraction of the individual flavor helicity parton distribution functions at small x. ? 2021 authors. Published by the American Physical Society.