Spin-isospin selectivity in three-nucleon forces

Abstract

Precision data are presented for the break-up reaction, ${}^2\mathrm{H}(\vec{p},pp)n$, 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 ${}^2\mathrm{H}(\vec{p}{,}^2$He$)n$ channel. These results are compared to the ${}^2\mathrm{H}(\vec{p},d)p$ 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.

4 pages, 3 figures, submitted to PRL