An alternative scheme for pionless EFT: neutron-deuteron scattering in the doublet S-wave

TL;DR

This paper proposes an alternative subtraction scheme for pionless effective field theory to improve the treatment of neutron-deuteron scattering, addressing issues with effective-range expansion and unitarity.

Contribution

It extends a previous scheme for spinless bosons to nucleons, specifically applying it to neutron-deuteron scattering in the doublet S-wave channel.

Findings

Addresses spurious sub-threshold poles in effective-range expansion.

Maintains unitarity in three-body amplitudes.

Provides a more consistent EFT framework for neutron-deuteron interactions.

Abstract

Using the effective-range expansion for the two-body amplitudes may generate spurious sub-threshold poles outside of the convergence range of the expansion. In the infinite volume, the emergence of such poles leads to the breakdown of unitarity in the three-body amplitude. We discuss the extension of our alternative subtraction scheme for including effective range corrections in pionless effective field theory for spinless bosons to nucleons. In particular, we consider the neutron-deuteron system in the doublet S-wave channel explicitly.