Nuclear Axial Currents in Chiral Effective Field Theory

TL;DR

This paper derives two-nucleon axial charge and current operators in chiral effective field theory up to one loop, ensuring finiteness and conservation in the chiral limit, and introduces contact terms for axial charge renormalization.

Contribution

It provides a comprehensive derivation of axial currents and charges in chiral EFT, including loop corrections, cancellations, and renormalization procedures, which were not fully addressed before.

Findings

Derived finite, conserved axial current in chiral limit

Isolated ultraviolet divergencies using dimensional regularization

Constructed contact terms for axial charge renormalization

Abstract

Two-nucleon axial charge and current operators are derived in chiral effective field theory up to one loop. The derivation is based on time-ordered perturbation theory, and accounts for cancellations between the contributions of irreducible diagrams and the contributions due to non-static corrections from energy denominators of reducible diagrams. Ultraviolet divergencies associated with the loop corrections are isolated in dimensional regularization. The resulting axial current is finite and conserved in the chiral limit, while the axial charge requires renormalization. A complete set of contact terms for the axial charge up to the relevant order in the power counting is constructed.