The chiral long-range two-pion exchange electromagnetic currents in radiative nucleon-deuteron capture

TL;DR

This paper investigates the nucleon-deuteron radiative capture process using chiral nuclear potentials and electromagnetic currents, highlighting the importance of higher-order corrections and the impact of regularization parameters on theoretical predictions.

Contribution

It introduces a detailed analysis of electromagnetic currents in nucleon-deuteron capture, emphasizing the need for higher-order corrections in chiral effective field theory.

Findings

Strong dependence of cross sections on regularization parameters

Small effects observed from three-nucleon forces and two-pion exchange currents

Significant theoretical uncertainties highlight need for higher-order corrections

Abstract

The nucleon-deuteron radiative capture process is investigated using the chiral nuclear potentials and the electromagnetic currents developed by the Bochum-Bonn group. While the strong interaction is taken up to the next-to-next-to-leading order, the electromagnetic current consists of a single nucleon current, the leading one-pion exchange one and is supplemented by contributions from the long-range two-pion exchange current at next-to-leading-order. The theoretical predictions for the cross sections as well as analyzing powers show strong dependence on the values of regularization parameters. Only small effects of the three-nucleon force and the long-range two-pion exchange current are observed. The dependence on the choice of regularization parameters results in a big theoretical uncertainty and clearly points to the necessity to include corrections from higher orders of the chiral expansion both for the nuclear forces and currents.