First analysis of world polarized DIS data with small-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>x</mml:mi></mml:math> helicity evolution
Daniel Adamiak, Yuri V. Kovchegov, Wally Melnitchouk, Daniel Pitonyak, N. Sato, Matthew D. Sievert
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 parton distribution functions at small $x$.