Search

We present a precise measurement of 3He analyzing powers for p-3He elastic scattering with the polarized 3He target at 50, 65, 70, and 100 MeV. The data at 65 and 70 MeV are compared with the theoretical predictions based on the modern nucleon-nucleon potentials. Large discrepancies between the data and the predictions are clearly seen at the angles where the 3He analyzing power takes the minimum and maximum values, which are not explained by Δ-isobar effects.

All deuteron analyzing powers for elastic deuteron-proton (dp) scattering have been measured with a polarized deuteron beam at 186.6 MeV/nucleon. They are compared with results of three-nucleon Faddeev calculations based on the standard, high-precision nucleon-nucleon (NN) potentials alone or combined with commonly used three-nucleon force (3NF) models such as the Tucson-Melbourne '99 or the Urbana IX. Predicted 3NF effects localized at backward angles are supported only partially by the data. The data are also compared to predictions based on locally regularized chiral NN potentials. An estimation of theoretical truncation uncertainties in the consecutive orders of chiral expansion suggests that the observed discrepancies between this modern theory and the data could probably be explained by including chiral 3NF's in future calculations. A systematic comparison to the deuteron analyzing power data previously taken at incident energies from 70 to 294 MeV/nucleon clearly shows that not only the cross section but also the analyzing powers reveal growing 3NF effects when the three-nucleon system energy is increased.