Chiral potentials, perturbation theory, and the 1S0 channel of NN scattering

TL;DR

This study combines experimental phase shifts with chiral expansion to analyze short-distance NN interactions in the 1S0 channel, showing that perturbation theory and a specific separation scale effectively describe NN dynamics.

Contribution

It demonstrates that a perturbative treatment of the long-distance chiral NN potential is feasible for R > 1.0 fm, providing a quantitative description of NN interactions in the 1S0 channel.

Findings

Short-distance dynamics can be approximated by a two-term polynomial for Tlab < 200 MeV.

A separation scale R .8 fm is suitable for describing NN interactions.

Perturbation theory effectively models long-distance parts of the chiral NN potential.

Abstract

We use nucleon-nucleon phase shifts obtained from experimental data, together with the chiral expansion for the long-distance part of the NN interaction, to obtain information about the short-distance piece of the NN potential that is at work in the 1S0 channel. We find that if the scale R that defines the separation between "long-" and "short-" distance is chosen to be \lsim 1.8 fm then the energy dependence produced by short-distance dynamics is well approximated by a two-term polynomial for Tlab < 200 MeV. We also find that a quantitative description of NN dynamics is possible, at least in this channel, if one treats the long-distance parts of the chiral NN potential in perturbation theory. However, in order to achieve this we have to choose a separation scale R that is larger than 1.0 fm.