Speaker
Description
We discuss the role of the chiral “triangle” anomaly in deeply inelastic scattering (DIS) of electrons off polarized protons employing a powerful worldline formalism which allows for the efficient computation of perturbative multi-leg Feynman amplitudes. We demonstrate how the triangle anomaly appears at high energies in the DIS "box diagram" for the polarized structure function $g_1(x_B,Q^2)$ in both the Bjorken limit of large $Q^2$ and in the Regge limit of small $x_B$. We show for the first time that the off-forward infrared pole of the anomaly appears in both limits. We motivate a small x effective action, consistent with anomalous chiral Ward identities, that shows how non-perturbative effects cancel the infrared pole, leading to an effective axion-like dynamics at small x. There are two non-perturbative scales that control this dynamics: one is the saturation scale and the other is the pure Yang-Mills topological susceptibility; we discuss how their dynamical interplay can be uncovered in polarized DIS at the Electron-Ion Collider.
References:
A. Tarasov and R. Venugopalan "Role of the chiral anomaly in polarized deeply inelastic scattering: Finding the triangle graph inside the box diagram in Bjorken and Regge asymptotics", Phys. Rev. D 102, 114022;
A. Tarasov and R. Venugopalan "The role of the chiral anomaly in polarized deeply inelastic scattering: Emergent axion-like dynamics and the small x effective action", in preparation.
