Spin-isospin selectivity in three-nucleon forces

Precision data are presented for the break-up reaction, H-2((p) over right arrow, pp)n, within the framework of nuclear-force studies. The experiment was carried out at KVI using a polarized-proton beam of 190 MeV impinging on a liquid-deuterium target and by exploiting the detector, BINA. Some of the vector-analyzing powers are presented and compared with state-of-the-art Faddeev calculations including three-nucleon forces effect. Significant discrepancies between the data and theoretical predictions were observed for kinematical configurations which correspond to the H-2((p) over right arrow,He-2)n channel. These results are compared to the H-2((p) over right arrow, d)p reaction to test the isospin sensitivity of the present three-nucleon force models. The current modeling of two and three-nucleon forces is not sufficient to describe consistently polarization data for both isospin states. (C) 2010 Elsevier B.V. All rights reserved.