Taking dibaryon fields seriously

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.