Global Analyses of Polarized DIS & SIDIS from Small-x Evolution

Quantifying the spin structure of the proton in terms of its quark and gluon constituents has been an animating goal of high-energy nuclear physics for decades. But a full understanding of the proton spin structure will necessarily require an extrapolation to small x, beyond measured data, where theoretical guidance is essential. In this work, we summarize recent developments in the theory and phenomenology of spin at small x, presenting results of a recent global analysis of inclusive and semi-inclusive deep inelastic scattering.