Exchange current contributions in null-plane quantum models of elastic electron deuteron scattering

TL;DR

This paper models exchange current effects in elastic electron-deuteron scattering within a Poincaré invariant null-plane quantum framework, demonstrating accurate predictions for low to moderate momentum transfers.

Contribution

It introduces a Poincaré invariant quantum model with exchange currents based on one-pion-exchange physics, ensuring current conservation and covariance.

Findings

Exchange current increases sensitivity to matrix element choices.

Two independent matrix element choices yield good data agreement below 8 GeV^2.

Model successfully describes elastic scattering observables at moderate momentum transfers.

Abstract

We investigate exchange current contributions to elastic electron-deuteron scattering using exactly Poincar\'e invariant quantum mechanics with a null-plane kinematic symmetry. Our model exchange current is motivated by one-pion-exchange physics. Exact current conservation and current covariance are satisfied by using this current to compute a linearly independent set of current matrix elements. The remaining current matrix elements are generated from the independent matrix elements using the covariance and current conservation constraints. The presence of the exchange current increases the sensitivity to the choice of independent current matrix elements. Two choices of independent matrix elements that have distinct motivations lead to a good description of all of the elastic scattering observables for momentum transfers below 8 (GeV)$^2$.