Using the covariant spectator theory (CST), we present two one-boson-exchange kernels that have been successfully adjusted to fit the 2007 world np data (containing 3788 data) below 350 MeV. One model (which we designate WJC-1) has 27 parameters and fits with a χ 2 /N data = 1.06. The other model (designated WJC-2) has only 15 parameters and fits with a χ 2 /N data = 1.12. Both of these models also reproduce the experimental triton binding energy without introducing additional irreducible three-nucleon forces. One result of this work is a new phase-shift analysis, updated for all data until 2006, which is useful even if one does not work within the CST. In carrying out these fits we have reviewed the entire database, adding new data not previously used in other high precision fits and restoring some data omitted in previous fits. A full discussion and evaluation of the 2007 database is presented.See Appendix D for further discussion of the nucleon form factor H . The indices 1 and 2 refer collectively to the two helicity or Dirac indices of particle 1, either {λλ } or {αα }, and particle 2, {ββ }.The covariant kernel V is explicitly antisymmetrized, as illustrated in the second line of Fig. 1. In its Dirac form it is V αα ;ββ (p, k; P ) = 1 2 [V αα ;ββ (p, k; P ) + η I V βα ;αβ (−p, k; P )], (2.6)where the factor η I = ζ (−) I +1 (with I = 0 or 1 the isospin of the NN state) accounts for the sign change due to the exchange of the isospin indices (which are suppressed in these formulas) and ζ = 1 for bosons and −1 for fermions. Hence, for fermions, the remaining amplitude has the symmetry η I =−) I under particle interchange {p 1 , α} ↔ {p 2 , β} as required by the generalized Pauli principle. This symmetry insures that 014005-2 COVARIANT SPECTATOR THEORY OF np . . . PHYSICAL REVIEW C 78, 014005 (2008)

First results for the triton binding energy obtained from the relativistic spectator or Gross equation are reported. The Dirac structure of the nucleons is taken into account. Numerical results are presented for a family of realistic OBE models with off-shell scalar couplings. It is shown that these off-shell couplings improve both the fits to the two-body data and the predictions for the binding energy.