We have performed a number of high precision measurements of cross sections and polarisation observables in p-d scattering from E_p = 245 keV to the breakup threshold. We observed very good agreement between experiment and calculations for the cross sections and tensor analysing powers while a discrepancy for vector analysing power persists and increases with decreasing beam energy. We demonstrated that current three nucleon forces cannot account for this puzzling observation and suggest that the origin of the discrepancy is either due to the inadequacies of NN potential models or, more likely, to the existence of a new type of three body force. We also confirmed for the first time the existence of a theoretically predicted pole in the doublet S-wave effective range function.

PACS numbers: 13.75.Cs, 24.70.+s, 21.45+v, 27.10+h