Polarization observables in three-nucleon systems

In the past two decades, several laboratories have produced a large amount of data for cross sections, analyzing powers, and other spin observables from various reactions in the three-nucleon system. The results allow one to arrive at a moderately good description of the data by only using the two-nucleon potentials in Faddeev-type calculations. The remaining discrepancies should, in principle, and aside from Coulomb and relativistic effects, be removed once the effects of three-nucleon forces are implemented. High precision data on elastic and break-up reactions show, however, that even after the inclusion of these effects, the picture is not complete yet and some ingredients are still missing in the calculations.