# Nuclear electromagnetic currents to fourth order in chiral effective field theory

## TL;DR

This paper derives electromagnetic nuclear currents up to fourth order in chiral effective field theory, including new three-nucleon charge operators, ensuring consistency with the modified continuity equation.

## Contribution

It provides the first derivation of the leading three-nucleon charge operator at this order, completing the electroweak current derivation in chiral EFT.

## Key findings

- Validated the modified continuity equation for all contributions
- Derived the leading three-nucleon charge operator
- Completed the fourth-order electroweak current derivation

## Abstract

Recently, we have shown that the continuity equation for the nuclear vector and axial current operators acquires additional terms if the latter depend on the energy transfer. We analyze in detail the electromagnetic single-nucleon four-current operators and verify the validity of the modified continuity equation for all one- and two-nucleon contributions up to fourth order in the chiral expansion. We also derive, for the first time, the leading contribution to the three-nucleon charge operator which appears at this order. Our study completes the derivation of the electroweak nuclear currents to fourth order in the chiral expansion.