Relativistic NN scattering without partial wave decomposition
  We consider the covariant Spectator equation with a One Boson Exchange (OBE) kernel, and apply it to the NN system. Relativistic effects such as retardation and negative-energy state components are included in that equation. We develop a method, based on the Pad\'e method, to solve the Spectator equation without partial wave decomposition. The convergence of the partial wave decomposition series is tested as a function of the energy. The on- and off-mass-shell amplitudes are calculated. The NN interaction was fitted to the differential cross section for NN scattering, in the energy range below the pion production threshold. 
G. Ramalho, A. Arriaga and M.T. Pena