Constructing chiral effective field theory around unnatural leading-order interactions

TL;DR

This paper introduces a momentum-dependent formulation of chiral effective field theory around an unnatural leading-order interaction, demonstrating rapid convergence and applying it to the triton binding energy.

Contribution

It proposes a novel momentum-dependent approach using a dibaryon field to improve convergence in chiral EFT for NN scattering, especially in the  channel.

Findings

Rapid order-by-order convergence in  channel

Successful calculation of triton binding energy

Analysis of chiral Lagrangian consistency and radiative corrections

Abstract

A momentum-dependent formulation based on a stationary spin-0 and isospin-1 dibaryon field is proposed to improve convergence of chiral effective field theory in the $\cs{1}{0}$ channel of $NN$ scattering. Although the two-parameter leading-order interaction appears to be unnatural, it nevertheless has the necessary features of an effective field theory. A rapid order-by-order convergence is found in $\cs{1}{0}$. As an application beyond the two-body level, the triton binding energy is studied and compared to standard chiral effective field theory with partly perturbative pions. The consistency of the chiral Lagrangian for the new formulation is examined by working out the pionic radiative corrections, and consequences of nontrivial chiral-connection terms are discussed.