Model Dependence of the 2H Electric Dipole Moment

TL;DR

This paper investigates how the calculated electric dipole moment of the deuteron depends on the nuclear interaction models, finding that one-pion exchange dominates and simpler models are sufficient for current measurement precision.

Contribution

It demonstrates the model dependence of deuteron EDM calculations using a separable potential approach and assesses the impact of different interaction components.

Findings

Full calculations differ from plane-wave approximation.

Tensor force contribution affects EDM results.

Short-range repulsion influences model sensitivity.

Abstract

Background: Direct measurement of the electric dipole moment (EDM) of the neutron lies in the future; measurement of a nuclear EDM may well come first. The deuteron is one nucleus for which exact model calculations are feasible. Purpose: We explore the model dependence of deuteron EDM calculations. Methods: Using a separable potential formulation of the Hamiltonian, we examine the sensitivity of the deuteron EDM to variation in the nucleon-nucleon interaction. We write the EDM as the sum of two terms, the first depending on the target wave function with plane-wave intermediate states, and the second depending on intermediate multiple scattering in the 3P1 channel, the latter being sensitive to the off-shell behavior of the 3P1 amplitude. Results: We compare the full calculation with the plane-wave approximation result, examine the tensor force contribution to the model results, and explore the effect of short range repulsion found in realistic, contemporary potential models of the deuteron. Conclusions: Because one-pion exchange dominates the EDM calculation, separable potential model calculations will provide an adequate description of the 2H EDM until such time as a better than 10% measurement is obtained.