Relativistic Treatment of Low-Energy Nucleon-Nucleon Scattering

An improved version of the one-boson-exchange model is presented. In addition to $\pi$, $\rho$, $\omega$, and $X^0$, the scalar mesons $\epsilon$ and $\delta$ are used with their physical masses. The broad width of the $\rho$ and $\epsilon$ mesons is taken into account. The relativistic Blankenbecler-Sugar equation is utilized over the laboratory scattering energy range 0 to 425 MeV. A better fit to the experimental $N-N$ data is obtained than in previous one-boson-exchange models. Reasonable values of the coupling constants are obtained, which agree qualitatively with other experiments. The fitting procedure was done including and excluding $S$ waves in order to test the influence of the core region. An approximate version of the above model is developed using the Schrödinger equation in place of the Blankenbecler-Sugar equation. A good fit to the experimental scattering data and the deuteron parameters is obtained with coupling constants similar to those of the relativistic model.