Axial anomaly and the delta_{LT} puzzle

TL;DR

This paper investigates the axial anomaly's role in explaining the discrepancy in neutron delta_{LT} polarizability measurements, using a Regge approach to incorporate the exchange of the a_1(1260) trajectory, and predicts proton delta_{LT} for future experiments.

Contribution

It introduces a Regge approach to calculate axial anomaly contributions to delta_{LT}, highlighting the significance of a_1(1260) exchange in resolving the neutron data puzzle.

Findings

a_1(1260) exchange significantly affects delta_{LT} predictions

The approach explains the neutron data discrepancy

Proposes proton delta_{LT} predictions for upcoming measurements

Abstract

The axial anomaly contribution to generalized longitudinal-transverse polarizability $\delta_{LT}^{}$ is calculated within Regge approach. It is shown that the contribution from the exchange of the $a_1^{}(1260)$ Regge trajectory is nontrivial and might have the key role to explain the large difference between the predictions of chiral perturbation theory and the experimental data for the neutron $\delta_{LT}^{}$. We also present the prediction for the proton $\delta_{LT}^{}$, which will be measured at the Thomas Jefferson National Accelerator Facility in near future.