Separating fact from fantasy in the proton spin puzzle: emergent axion dynamics and spin diffusion to the infrared.

by Prof. Raju Venugopalan (BNL)

Friday 19 Jun 2020, 16:15 → 18:15 Europe/Berlin

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Anomalies in gauge theories are of interest because they represent global features of the theory that are not contained in the Lagrangian. We discuss here the role of the chiral anomaly and its interplay with slow (small x) parton dynamics in the hadron. Subtle features of the dynamics involving non-commuting limits can be carefully teased out in a worldline formulation of quantum field theory. As a particular example, we consider the QCD evolution of  the iso-singlet axial vector current probed  by the g1 structure function measured in Deeply Inelastic Scattering experiments. We present a conjecture regarding the non-perturbative dynamics that determines how the spin of the proton diffuses to small x.