Taking dibaryon fields seriously

TL;DR

This paper develops a low energy effective field theory for QCD in the baryon number two sector, incorporating dibaryon fields to accurately describe nucleon-nucleon scattering at energies up to 50 MeV.

Contribution

It introduces a renormalizable, well-defined counting effective theory with explicit dibaryon fields, improving the description of nucleon-nucleon interactions at low energies.

Findings

Accurately describes phase shifts in nucleon-nucleon scattering up to 50 MeV.

Provides a renormalizable effective theory with explicit dibaryon degrees of freedom.

Achieves manifest unitarity at leading order in scattering amplitudes.

Abstract

We propose a low energy effective field theory of QCD at the scale of pion mass for the $N_B=2$ sector, $N_B$ being the baryon number, which contains two dibaryon fields in addition to the nucleons and pions. It has a well defined counting, is renormalizable and the nucleon-nucleon scattering amplitudes are manifestly unitary at leading order. We work out a lower energy effective theory for nucleons with energy much lower than the pion mass and three momentum comparable to it, which also has a well defined counting and is renormalizable. The dibaryon fields must also be kept as explicit degrees of freedom in this theory. We calculate the scattering amplitudes at next-to-leading order for the $^1S_0$ and $^3S_1$ channels in this framework and obtain an excellent description of the phase shifts for center of mass energies in the $0-50 MeV$ range.