XXVIII International Workshop on Deep-Inelastic Scattering and Related Subjects

The role of the axial anomaly in polarized DIS: Emergent axion-like dynamics and the small x effective action

14 Apr 2021, 14:03

18m

Virtual (Stony Brook, NY)

Contributed Talk Spin Physics Spin Physics

Speaker

Dr Andrey Tarasov (The Ohio State University)

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.

Presentation materials

Youtube Link