Light-front projections of the Bethe-Salpeter amplitude and the 4D electromagnetic current for an interacting two-fermion system

TL;DR

This paper reviews a method for reducing the four-dimensional electromagnetic current of an interacting two-fermion system to a three-dimensional form, ensuring key physical properties are preserved for future nuclear physics applications.

Contribution

It introduces an exact 3D reduction technique for the 4D electromagnetic current in two-fermion systems, maintaining gauge invariance and Fock decomposition.

Findings

The 3D current satisfies the Ward-Takashi Identity.

The approach facilitates future applications to few-nucleon systems.

Properties of the reduced current are consistent with physical requirements.

Abstract

A recent approach for constructing an exact 3D reduction of the 4D matrix elements of the electromagnetic current for an interacting two-fermion system, is briefly reviewed. The properties of the obtained 3D current, like the fulfillment of the Ward-Takashi Identity and its Fock decomposition, will be illustrated in relation with future applications to few-nucleon systems.